USA New Wall - a proposal for a high performance commodity wall system

We've been kicking this idea around for about a year, ever since we created our 0970 Lagom House for a design contest. Inspired by our study of Swedish construction we wanted to create a high performance wall for the US market that lent itself to panel fabrication, and was accessible to any builder using the skills and experience they already have.

Why not use new materials and techniques? How can you make a New Wall that everybody is going to know how to build? We want to create a wall that can be widely adopted, something that any builder can start building tomorrow without any new training, without finding any new suppliers, with out changing the way they run their business. If we want the greatest number of builders to build more efficient houses we need a wall they understand immediately, we need a wall that they can purchase materials for from their existing suppliers, use their existing sub-contractors, and a wall that is familiar enough for them to reliably price and schedule. New materials and new techniques throw off all of this and become barriers to adoption. We don't want barriers. We want everybody to start building more efficient houses. Continue reading for a detailed explanation of this simple but robust wall.

We proposed an initial version of this wall when we designed the Lagom House, but now we believe we've made significant improvements. Gone is the exterior foam insulation layer. Foam insulation is expensive, and it is difficult to place on the exterior without creating an unwanted vapor barrier. Instead we rely on lessons from the Swedish wall to replace the thermal break that foam offers.

First we are starting this with a wall design for northern climates. Designs for southern climates are different, particularly in the vapor profile. So keep in mind this design is for a heating centric climate. We are planning this wall for 2x6 or 2x8 versions. The 2x8 versions offer a greater insulation level for those that desire it. Starting from the interior here are the layers of the wall system.

• Interior finish is assumed to be gypsum wall panels, the commodity wall finish in the USA.

• Next we have an electrical and plumbing furring space. This space is created with 2x2 furring members, and is insulated with fiber glass batts, 1.5" thick for an insulation value of R6-6.5 depending on the product chosen. This insulation is typically more rigid than batts and is sold as a fiberglass "board". This actually facilitates cutting openings for electrical boxes and other penetrations. The horizontal furring allows the insulation layer to break the thermal transfer of the main stud wall in the same way exterior foam insulation does, but it does so with out creating a problematic exterior vapor barrier, without expensive foam insulation, and with the added benefit of a dedicated wiring chase space that allows us to build a tighter primary wall. Thank you Sweden.

• Next is a continuous vapor barrier - a plastic sheet that runs continuously from top plate to floor plate. Because all of our wiring is in the furring space there is no reason to penetrate this vapor barrier allowing for a very air tight wall to be created.

• Next is our insulated stud space based on 2x8 or 2x6 studs, 24"oc will suffice for these strong studs. Un-faced batt insulation can be used since we have an independent vapor barrier layer. And since there is no wiring or other obstacles in the wall the batts can be installed neatly, and completely filling the voids. Batts have a bad reputation for sloppy insulation. One thing the Swedish walls show us is that its not the batts, but the obstacles that are the problem. These walls can be as tightly filled as any highly insulated wall without the wires and piping to struggle against. Now what insulation to use? The major insulation manufacturers in the US offer two densities. Always choose the higher density with the higher R value. For a 2x6 wall that will be R21 batts. For the 2x8 wall we have quandary - US manufacturers do not make batts for 2x8 walls. 2x6 walls, yes. 2x10 ceilings and floors, yes. 2x8s you are out of luck. Until they begin we have two options. We can use 8" R30 batts, and compress them 1" into the 7.25" space of a 2x8. This will diminish their R value somewhat - don't count on more than R28. Or you can do two layers: a 1.5" R6 + a 5.5" R21 for a total of R27. In the meantime, Owens Corning and Certainteed - WAKE UP! We need wall batts for 2x8 walls.

• Last but not least is our sheathing and exterior wall system. This remains open ended. Commodity builders are going to want to use their composite Zip sheathing and cheap vinyl siding. Green builders will use a sophisticated rain screen cladding system. And everything in between. All will work here.

Once accounting for total wall R values that take in studs and solid framed portions of the wall you can probably expect the 2x6 wall to come in R23-24, and the 2x8 wall R30-31. This is clearly enough to contribute to a Passive House, but even if you are not looking to build a certified house you have an easy to build high performance wall using commodity construction products. If we can get builders making houses with walls like these then soon we can forget about certifying standards and just build every house to a high level of performance. We can do this now. Its time to demand it.

Letters from Sweden - The path lies in revising our roles

Scott, my partner is studying Swedish housing, posted a comment at the Green Building Advisor blog post on my look at Swedish walls. His comment was very thought provoking, so much so I thought it important to repost it here. It is all about how the roles required to build houses in Sweden are different than they are here. As such the expectations are different, and coming to grip with that will probably be more important than any of the hammers and nails involved in changing what we do. In the end buying a house in Sweden is more like buying a kitchen in the US.

I think that any benefits from the Swedish methods are going to be because guys like the ones reading this figure out how to make all this both profitable and beneficial to their lives - because it is good for customers, profits, and their own sense of enjoyment of work. There are some important cultural and trade practice issues. James mentions "replacing skilled labor" by the idea of ordering his walls ...

I wanted to comment about how I saw this kind of factory based building impact the lives of the people who build houses in Sweden, as far as I could tell from my time there.

The Swedes had managed to change the supply chain in light residential construction and consequently they changed the nature of the work involved in building a house.

The closest way I can describe it is to compare it to the work of cabinet installers in the USA. The builders in Sweden come to the job with the same level of "kit" to build a house that we would take to install a kitchen. It is not that cabinet installers in the USA are unskilled - they just need different skills than framers.

The builder I worked for would get calls from the factory to bid on the installation of a house, the rates of what was involved were more or less given and the factory was always looking at this as one in a series of jobs (ie everyone involved expects to work together again next week) so I think bidding really just meant agreeing to take the job, meeting the schedule and price on offer -factory was not competitive bidding so much as getting agreement to perform. The factory for its part was selling houses, so they were bringing the customers to the builder.

This was not unlike the way a kitchen design show room has a PM - who work with the customer order the job and see it into the hands of the installer, who is though not an employee often a trusted sub of the kitchen company.

In fact the way that a family would buy a house in Sweden, was a lot like the way a person in the USA would buy a kitchen. They would go to a "store" where "salespeople" would talk to them about the features of their products. In Stockholm there the house factories had all built an "expo" so the customers could see all their choices and what the various factories had on offer. The Swedish market is small and ultra competitive. They are very "customer centric" as a result of this.

The builder I worked for did a base line business in "installing houses", and then he did additions and remodels he had about 10 guys working for him, his remodeling work was exactly like they way we do it and he could and did build stick homes, but he did what I thought of as a "baseline" trade in working for the factory who was selling houses to customers to build "on their lots" - his crew would meet the factory trucks, the factory would send a guy and the truck driver who would work with the builders to get the house up and closed in. All the material that the "installer" would need was supplied by the factory. The effect of this was a massive elimination of PM responsibility on the part of the builder.

The role of "GC" therefore on a new build in Sweden is radically different. The only people who build houses they way we build houses are doing something for instance very fancy or that is outside of the what the factories think of as "housing".

The way you buy and build a house in Sweden has been rationalized away from our model (which we should be clear is looked up to world wide, and has given Americans a very high standard of housing because of our pioneering in our building systems think Chicago and the light wood frame in 18??) ... so I'm not in the "we suck at houses camp - I'm more in the how to we get better at houses camp). My view is that the Swedes took all our innovation and innovated it even more.

The effect of this on a "build" is that there are guys in offices, and there are guys on the tools, and the guys in the office are invested in the build in ways that lumber yards and our modular factories aren't - all because they have different conceptions of their jobs too.

There was a lot of "waiting" in a one off Swedish build. The work would happen in intense bursts, but there was very little wasted effort. Everyone would leave and do something else.

So my view is that the Swedish builders are different skilled, and I thought the life of the guys I worked with was good, they didn't grumble about the old days when they used to frame houses, if anything they seemed to like the fact that all the work they had to do was rationalized. There was this sense of efficiency, that is recognizable no matter our language. We all can tell when things are "flowing" or when we are working slow and wastefully or don't have the tool or material we need or have to go find out something or spend our time talking or arguing ... when the walls would arrive they were connecting them, and that took skill, just like when cabinets arrive in boxes to make them all look like a perfect fitted kitchen.

This whole system is much more "interdependent" than the "GC" model ... I think the biggest obstacle (if this offers some "green building benefit") is how we change our understanding or roles and habits (all of which are hard won and valuable to us and help us survive where we are) but also prevents change and evolution ... so this kind of discussion is really the way we have to go, a factory guy, a field guy an architect, have all got to be open to "new ways" ... the useful thing about the Swedish example is that if you are going to try something new, it helps to have an example so you aren't off in "prototype" land inventing the wheel

This is fully mature industry, full of normal people and real businesses in real competition working for real customers with the same dislike of paying too much as customers everywhere.

There aren't many of these "alternate realities" for us to learn from, partly because we Americans are playing at a very high level ... so most of the world looks up to us. There are only a few cultures, like the Nordics, who take our example and improve on it. that is what has happened here.

Letters from Sweden - A closer look at the Swedish wall

Today we're going to take a closer look at common wall construction in these Swedish factory houses we've been studying. The Swedes build their energy efficient homes using fairly ordinary materials that are not very different than what we use in the US. Ultimately we would like to propose a analogous wall system composed of materials widely available in the US - an American version of the Swedish wall. But first we have to look closer at what they are building.

Several of our earlier posts in the Letters from Sweden series touched on this. Most recently we looked at an automated assembly line, and through observing the assembly process we could see the various layers of the wall. Now we'll look closely at each layer using examples from a few factory web sites. Some Swedish factories market themselves as being green and some offer passive house options straight from the factory. What we will look at here is what I've found in my research to be very typical of Swedish house construction. A baseline if you wish of what the average wall in a Swedish house looks like.

First we must put this in perspective with a quick consideration of the average construction in the US. In the USA a comparitve average wall system would be 2x4 stud wall, with strand board and vinyl siding over tyvek on the outside, gypsum drywall on the inside, filled with R13 fiberglass batts. That's it. This wall is thin, cheap, and has poor energy performance. If you are in a colder US climate this may be offered with 2x6 studs and R19 insulation, or with a thin foam insulation layer in place of the strand board on the 2x4 wall. This is just enough to meet our meager energy code requirements. In the US vapor barriers which are supposed to keep the interior of our walls free of moisture typically come bound to the insulation batts. This makes for an open seam at every stud, and a hole where ever a switch or outlet is placed. As a result the wall is not air tight, not even close.

Ok, that is the typical in the US. Let's look at Sweden.

This wall construction diagram is from a factory called RejnäsVillan and is a good typical example of their practices. This diagram can be found on their site here.

Starting with the framing, they are using 195mmx47mm studs, which translates roughly to 7 3/4" deep, or a half inch deeper than our 2x8s. This stud space is completely filled with mineral wool insulation which is denser and has a higher R-value per inch than our typical R13 and R19 insulation.

Moving to the outside the stud wall is sheathed with a panel that is either a hardboard (like a masonite) or a gypsum board cladding. This is covered with an air barrier like tyvek if it is not already a component of the hardboard/gypsum panel. This is in turn layered with horizontal furring, approximately 47mm thick, and then finally clad with thick solid wood siding boards.

Moving to the inside, directly in board of the studs the wall receives a heavy plastic vapor barrier that is applied in a continuous sheet. On top of that is a horizontal furring and this 47mm space filled with more mineral wool insulation. This is in turn clad with a particle board layer, or sometimes solid tongue and groove wood. And finally the interior gypsum panels. This deserves some explanation. The interior furring space serves a the place to run wires and plumbing, so there is never any electrical boxes making holes in the vapor barrier layer. This allows the house to be built air tight. This is analogous to the "disentanglement" layer that Bensonwood uses in their wall systems. The particle board layer is a convenience, to allow a homeowner to hang shelves, pictures, or cabinets anywhere without concern - there is always solid anchoring. The feeling is the additional material is cheap, and its presence adds greatly to quality, a logic I find difficult to fault.

Last of all this layering of furring strips and studs creates a thermal break that decreases the direct conduction of heat through the studs. This is something that Passive House proponents struggle with here in the US, leading many to opt for exterior foam layers to isolate the studs. The problem with this strategy is the foam is an inherent vapor barrier. In a heating climate that barrier wants to be on the inside. It can be done on the outside, but only at risk that with extreme temperature ranges the dew point could swing into the stud space and cause condensation, and then reduced insulation performance and mold hazard. I think the Swedish strategy is superior, and it is effective - Swedish factories use the same strategy in their Passive House wall systems.

So why do the Swedes build such quality walls, and the US not so much? Number one as a nation they were committed to reducing their energy consumption and they've been remarkably successful at that. We have not. Number two, their factory process allows them to build sophisticated walls like these efficiently. With our cheap walls factory building makes little difference. There is simply not enough value there to save very much. Its just as profitable to build on site when your walls are so cheap and simple. The Swedes however use the factory to make every house very high in quality, and very energy efficient. If we ever hope to do the same we will have to turn to a similar factory process.

Next we'll speculate on what a similar wall might look like built in the US.

Letters from Sweden - Automated panel building in the USA

We've looked at Swedish examples of an automated panel building line, and a largely manual panel building line, but how about in the USA? There are some manufacturers here that have imported these machines and run automated panel building lines. The difference? The Americans do not do closed panels, meaning panels finished inside and out. In fact they don't finish them at all.

Well why not you might ask. If they are buying the machines from the same company that makes them to build finished closed wall panels, then why don't the American companies do the same thing? The obvious answer is that the rest of the construction materials that need to be incorporated don't lend themselves to being installed off site - this was the focus of many of our earlier Letters from Sweden posts (read back to see the detail). Hence the effort to build closed panels here becomes more difficult, expensive, and finally does not offer an advantage over completing the walls on site.

Another aspect of why it makes less sense here is the quality of the construction in Sweden. The typical wall construction in Sweden is much more substantial, many more layers to the wall assembly, and many more steps to complete a wall. Hence if those steps are automated or made more efficient there is more opportunity to build value in the closed panel process. The cheap and thin wall construction we use here does not offer as much chance to save effort.

So what we are about to look at is an American panel line. There is no identification but I believe this to be one of the larger merchant home builders in the US. Without a doubt this company knows how to build houses profitably, and the fact that they are using a sophisticated automatic panel framing line like this is impressive and speaks to the sophistication of these large US builders. They likely also own a truss fabricating line for making their own roof trusses rather than purchasing them from a third party. They have in their own way squeezed as much waste out of their process, and are generating as much profit as they can by adopting these methods. Lets look at the line.

Here is an overview of the line which builds both sheathed exterior wall panels, and interior partition frame panels.

This machine is the stud feeder, which takes a stack of wall studs feeds them into the panel assembly one at a time.

The stud is positioned, and nailed into place in one operation, precisely spaced. Its worth mentioning the woeful quality of the American lumber compared to the beautiful clear grained cabinet grade wood used for framing in Sweden. Its shameful.

The sheathing is automatically picked from a stack and fed into a saw that cuts the sheathing to the size required for the wall panel.

The sheathing panel is then conveyed to the framed wall and positioned.

A nailing station applys the nails spaced as required by code.

Then finally the window and door cuts are made, and the long assemblies cut into individual wall panels. The work is then complete and the unfinished wall panels are stacked for delivery. Its interesting to note that the panels are stacked horizontally here. What this means is they may incur more handling of the panels to reach the ones needed in proper sequence, another small inefficiency. Compared to the Swedes, they store, and ship to site vertically which allows any wall panel to be accessed as needed. Some factories use transportable racks which keep the wall panels vertical, the entire rack loaded on the truck, unloaded at the site, and later returned empty, all in the name of keeping the work flow slightly faster.

Here then is the entire video:

The closing question is why, if this assembly line is in the US, why don't the US home builders offer a range of styles as do the Swedish factories. First, its only the very biggest and most sophisticated US builders that build this way. In Sweden even small companies use an efficient process such as this that permits them the flexibility to cater to the customer's taste in modern. So yes, the machines are here, but it underscores my earlier point - its not about the automation, its about the process.

0751 RS House - settled in for the holidays

I received some current photos of the completed house from the Owner today. Its very gratifying to see an xmas wreath on the dining room wall, and the house participating in the life of the owner's this way.

This is what modern is about for us. Its not some minimal and stark photo in a magazine, its not unhappy hipsters ruminating about the pedigree of their design accessories. Its living a life like anybody lives in a modern home that is true to your values and represents who you are. And this time of year that means holiday decorations, sharing your home with your friends, and finding comfort and rejuvenation at home, something beyond the need for shelter and refuge. That by all means happens in a modern home as much as any other, don't let anybody suggest it is not so.

So for all you lucky enough to have your modern home, and all those still wishing for one, keep that hope alive for each other and have a good holiday. More new photos of the RS House are posted to the Flickr set.

Letters from Sweden - A look at a simple assembly line

Last time we looked at a near fully automated closed wall panel assembly line. I said that you really don't need all that automation to build houses the Swedish way, so today we'll look at a much simplified process. This is the way most houses in Sweden are built.




What we are about to see is the Swedish Flip Table - a hydraulic tilting table that allows you to easily turn a wall panel over so you can work on both sides. That is the key really - keep the panel on a table so you can reach everything without ladders, and be able to flip it over so you can work on both sides. Each side of the Flip table is a workstation where you can complete both the inside and outside of the wall. We saw this table in the full automated line, but here we can see how just this table allows a factory to set up a simpler and effective work flow. In this example it is supplemented by an additional work table on either end of the flip which expands the total workstations to four. Smaller factories often use just the flip table, or two.



Here is a diagram of the line, not labeled as with the automated line, but its so simple we'll explain below:







Here are the steps in the line:

- the first table is the framing table. It has hydraulic clamps which allow you to set up the entire stud panel, and then rapidly nail it all into place.

- the flip table is in the middle. Both sides of the table can be used at once, when the second side is finished and clear, the panel from the first side is flipped over and the work begins on the other side.

- the stand up table is the last table. The work on the panel is finished there, and then the panel is stood up on end to be taken away for wrapping and transport.

Lets look at the sequence in detail:







Studs, top, and bottom plates are first cut according to a list made for the wall panel. A factory may have an automated cutter, or simply a man with a cut list. The studs for a given panel are staged at the end of the table and the pieces are laid out. The table then clamps them all together so they can not move, and the workers can nail them all very rapidly. Note that unlike other examples we've looked at the windows are not installed, but in other examples a separate worker would have been building the window opening frame and another putting the window into it and then adding it to the staged material here.







Also at this time the lift straps for the panel are installed.







While still on the framing table insulation is installed filling the stud spaces completely.







Then the panel is rolled down the line onto the first half of the Flip Table.







The interior vapor barrier is added next. Note the table includes a large roll holder so that the handling of the large sheet is easy and fast, nothing like trying to hang sheets on a vertical wall.







next the interior is finished







Electrical boxes are put in place, and the batten strips that hold the gypsum board. Note that all of the electrical work is inside the vapor barrier. No punctures, no air leaks.







Next the interior layer of insulation goes in-between the battens. The change in orientation of the battens and studs means that this layer of insulation prevents any direct thermal bridging of the studs to the interior. This is something that we are struggling with in high performance houses in the US. Many well respected experts have been advocating for exterior foam for the same purpose, and reversing the typical interior vapor barrier to the exterior because the foam insulation will block vapor anyway. I much prefer the Swedish technique we see here.







Next the interior gypsum board is mounted. What we see here is the magnetic finder on the hole saw for the electrical boxes. The magnet centers the drill, and a round hole is cut for the box. Easy, fast, and designed to be that way. Why are our electrical boxes square?







Drywall done, time to flip the panel.







Now work proceeds on the exterior of the wall. First sheathing panels are added, and then batten strips for the exterior siding. In this case the panel will get horizontal tongue and groove boards, so the battens go vertical over the studs.







When battens are done the panel is rolled to the last table, the stand up table.







Siding boards are installed, and all the window and door openings trimmed.







When the panel is done the lift straps are attached to the conveyor track above and the wall panel is tilted to vertical.



If this was a smaller line with only the flip table, then the flip table would be used to bring the wall panel to vertical.







The slack in the cables from the conveyor are taken up as the panel is raised. When vertical it swings off the table and the worker can push it away for wrapping and to await shipment.



And so even a small factory can set up a very efficient work flow for creating their wall panels. No multi-million dollar automated lines, and few excuses either! Enjoy the video below of the entire process:

Letters from Sweden - A closer look at a closed wall panel assembly line

We've described the Swedish method of building off site in several past blog posts, but today we will take a closer look at the assembly line to get a better idea of how you build walls this way.




The first thing I have to explain is that a fully automated line like this is not needed to build houses the way they do in Sweden. In fact most of the small factories do not have these complex machines, and are using a simpler process, more manual, less automated. But what they both have in common is a reduction in wasted effort, a lean process of building. In the next few days we'll also look more closely at how they build without all this machinery.



But first this machinery. The Swedes build wood houses in a particular way, and so a Swedish company named Randek Bautech builds machines that automate the way the Swedes build houses. They can't expect a German company or a Japanese company to do this, so they invent their own. Makes perfect sense. What exactly do I mean by that though? Well for instance the Swedes use solid wood siding when they use siding on their houses - not vinyl as common in the US. So they create a machine that can nail their solid wood siding. Obviously this would not have much use for a large US builder who primarily uses vinyl siding. Ok, got it?



Randek Bautech provides a great video of this line in action which I will post here. But first lets look at the line:







It goes in this sequence:

- top and bottom plates of the stud wall cut to length

- sub panels means the studs that form up window and door openings

- insulation cut to fit the stud spaces

- framing station is where the wall studs and plates come together

- board and breather is exterior sheathing board, and the vapor permeable air barrier

- cladding is where the solid wood siding is applied

- butterfly is their name for the flip table that turns the wall panel over

- indications of chain conveyors are areas where the wall panels are transferred between stations and some manual portions of the work are completed.

- finally the up raiser is the machine that stands the panel on end so it can be conveyed to be wrapped and loaded on the truck.



Lets look at some stills of each step now.







This is the sill plate being formed. It is in two parts bridged by a thin panel - this is because it sits on top of a center plate that is pre-attached to floor, so the wall panel aligns itself when placed. This makes sense because your precision happens when you nail the center plate to the floor - easy, not when a 2000kg panel is dangling from a crane - not easy.







Here is the sub-panel station, where we see a window being installed into the framed opening. Yes, that's right, the window is installed before the wall is even framed. This whole assembly will then find its place in the line of studs making up the given wall.







This machine unrolls the insulation batts, and cuts them to fit the spaces coming in the wall panel. One of the worker will tamp them in to be sure they are positioned correctly.







The framing station where the plates and wall studs are joined - now you have a panel.







This is where the wall sheathing is cut and applied, and the wall wrap put on the exterior. From here it enters one of the transfer sections where battens are applied for the upcoming siding.







Here the siding panels are automatically nailed to the wall panel over the battens. Each of those nailing lines are following a batten line, with additional nail lines positioned over and under the window to fasten the ends of these short boards.







The flip table makes short work of turning over a large wall panel so you can work on the other side. Now the interior air barrier can be fastened. In the video the line stops there, but the transfer area here can also be used to fix interior battens, electrical boxes and wiring conduits, and finally the interior gypsum board.







And finally the wall panel is stood on end, passed by cart to the next worker who will wrap it and then stow it in a rack, and eventually loaded on the truck for delivery.



And like this an entire house can be fabbed in a day, easily. As we've seen in other videos those panels then delivered to a site with a waiting slab will also be assembled in a day. I assure you the bulk of wasted time has been wrung out of this process. Enjoy the full video below:

PreFab is Dead - the staggering FAIL of US Housing

As we enter Day 18 of my expo of Swedish Factory Houses on the LamiDesign Idea Log I can barely contain the magnitude of my outrage. I had to write this blog post simply to stop myself from going to the window of my studio, sticking my head out of the opening and screaming "I'm mad as Hell and I'm not going to take it anymore!" You have to understand the staggering, colossal, and tragic scale of the FAIL of the US Housing Industry to serve its customers.

So here is the deal. Sweden, a small country with the population of NJ, the size of California, manages to offer within its limited market dozens, I'll wager hundreds of modern house designs to its customers. And its not like each home builder has one or two token modern houses in the catalog. They all have a dozen or more. Even if you are part of that smaller margin that likes a modern house, you still have choice of dozens of houses where ever you might look to build a house. Yet here in the USA our corresponding mainstream home builders offer none. Nothing. Nada. Something is clearly wrong here. Our home builders say "if its not what most people want, then I won't offer it." In Sweden the mantra is completely reversed: "if its something that somebody will want, then we'll certainly offer it."

It makes some sense. Why bother to engineer the house and produce marketing material for a design that won't sell as well? Truthfully, that is not the reason. These costs are minimal, earned back in a single home build as the Swedes clearly demonstrate. The reason is because the American home builders can not build these houses as profitably as their mainstream offerings. Their carpenters in the field building repetitive houses get into a flow of their work, the dimensions and layout of the standard plans in a subdivision eventually committed to memory. They may use different siding on each one or a different facade treatment, but the houses are from a limited group of plans and the framing work is equal. How can they introduce into that work flow one or two modern homes with different plans and different massing without breaking their pace. Those one or two homes will take them longer to build, and will make less profit. Why even offer them? They don't.

Lets have a look at a Swedish subdivision. The houses here are all being built by Sävsjö Trähus whose designs we've just been posting in the idea log. Scott Hedges pointed this out. He writes:

This web page shows 5 houses built by Sävsjö Trähus all sold out of the Solna office. Solna is a really nice suburb of Stockholm where Ericsson is HQ (also where Skanska is) - these are all examples of the kind of houses that would be built by wealthy Swedes, executives in these companies.

Each of these was made by the same crew of guys in central småland. Each built, loaded, and shipped in a few days each, as part of a serial production of around 100 house packages like this a year. Not a lot of sophisticated automation or fixed systems, just teamwork and good planning. All built on their flexible little flip table in central smalland and carted up to suburban stockholm.

They could care less what style or kind of house they build. They just want it to be what you want and be affordable. Severe modern, ultra traditional, mildly traditional, mildly modern ... it just doesn't matter. They have every possible style of house that is reasonable for people to build.

Sign here. We'll send the permit drawings, and ship the whole house in a few weeks.

so you see nice traditional Swedish vernacular like this above, but you also see their functional modern style like this below:

No problem. Why wouldn't you do this if you could. Well they can. This is MMC and OSM. This is what it is capable of. Each of these homes was just as profitable as the next, because their process is geared up to serve the customer what they want. It is style neutral and value bias - whatever builds the most value for the customer leads the process. Forcing a buyer who wants a modern house to choose a traditional house clearly does not build value for that customer.

Are you mad? Are you ready yet, ready to not take it anymore?

Coming In From the Cold - the story behind the story or How the nations top scientists gave up on US home builders

As much as my Swedish housing industry research colleague Scott Hedges and I would like to think we discovered the success of MMC in Sweden, we have to credit work which has encouraged our thinking and research. The methods we are examining were described years ago by much greater minds than ours.





During the 1980's scientists working at the Lawrence Berkley Energy lab noticed that less energy was being used to heat homes in Sweden than in other industrial countries. Was the data wrong? No, Sweden was outperforming other countries. A man named Henry Kelly, who was director of a group called American Council for an Energy Efficient Economy, along with a Berkley scientist Lee Schipper, and colleague Stephen Myers, realized that the Swedes weren’t just building a few energy efficient houses. Rather they had managed to make the average house, the kind built every day much more energy efficient. The Swedes had changed housing though a comprehensive effort encompassing the building products industry, the construction industry, national building codes, national lending practices, and trades unions.



The USA had just passed through a severe energy crisis that rocked the entire economy. Our band of researchers saw what this could mean to energy policy in the USA. Determined to quantify the progress in Sweden, they secured a grant from the German Marshall Fund and cooperation from the Swedish Council for Building Research to do something that is rarely (if ever) undertaken by the building industry: an international collaborative study to find out what actually went on in Sweden and how it might inform the way we build and structure our housing industry here in the US. Their report was done in 1985 and the results distilled into a small book called Coming In From the Cold: Energy-Wise Housing In Sweden.



This book is the story of what they discovered. It documented the progress and results of the change to housing in Sweden and how the various factors in research, building, manufacturing, lending, codes, and oversight all contributed to the change. The book is a gospel for learning from the Swedish Housing industry. Its all in there, and it was communicated to congress and the National Homebuilders Association and anyone who would listen. Anybody with half a mind and this short booklet at their side could reshape the industry in a heart beat. A few thin pages could show the way forward to improve the quality of our construction, reduce energy use nationwide, and extend the benefit to anybody who wished to buy a home. They truly stood at the precipice of a new American housing industry.



Then like wisdom cast into the void, builders did not read the book and the housing industry who Schipper and Kelly were trying to help snubbed them.



Today, Lee Schipper is an internationally recognized expert on energy in transportation, and a co-recipient for a Nobel prize in climate change. His experience trying to convince American homebuilders to see the benefits of MMC and OSM left him feeling that they were hopeless to change. Schipper is still skeptical of the capacity for change in the homebuilding industry, saying recently "Swedes build good shelter, we build Tax Shelter".



Henry Kelly, went on to be the president of the Federation of American Scientists. Though Kelly has been honored for "promoting the use of physics for the benefit of society", he too hasn't been able to convince American homebuilders that stopping energy loss in houses requires changing the way we build. Kelly has returned to work again directly on the issues of energy efficient building, appointed by the Obama administration to be the Deputy Assistant Secretary for the Office of Energy Efficiency and Renewable Energy at the U.S. Department of Energy.



The impressive careers of these two men, who have been honored for their work in every field except the building industry who ignored them, only highlights the tragedy that their work on Swedish housing does not grace their credentials today. Their revolution in American housing is glaring in its absence. The very people who stood to gain from these insights turned their back. The scientists went on to earn respect in other fields where science is valued. Meanwhile the NAHB gave the world the McMansion and went on to make a living lobbying against the kinds of policy innovation that led to Sweden’s success. And we know all too vividly exactly where that ended up taking us.



So here we are, 30 years later, and while I would be the first one to point out that the homebuilding industry in the US is largely the same as when Schipper and Kelly wrote Coming In From the Cold, the fact is that there are now greater pressures to change than there have ever been. The Passive House movement has clearly taken hold in the US. Energy performance is becoming a priority, and work weatherizing older buildings is seen as a way to both put people to work and help the nation's energy policy. Despite our progress in energy codes nothing points a clearer way forward than their book's recommendations. Residential lending in the USA, now clearly in a shambles, would also benefit from the lessons they've spelled out. Their book shows the way lending can be used to facilitate change in the industry, a tool for better housing rather than an out of control financial medium. And now as the housing industry is saddled with unsold and cheaply built oversized homes, its clear that a new kind of home, energy efficient, rapidly built, and smartly financed could put this housing industry back on its feet. Clearly there is demand for this new kind of home that the industry never got around to building. The kind of home that so long ago Kelly and Schipper showed them how to make. The emergence today of skilled and innovative builders like Bensonwood is validation of their prescient work done 30 years ago in Stockholm.

Greg Lavardera's Modern House Plans + Bensonwood

All week we've been talking about factory house building in Sweden, and American timberframer and house manufacturer Bensonwood. The good news is that Bensonwood has begun to offer our house designs in their energy efficient building systems. The first house to be offered is the XHouse2.

We went through a detailed redesign of the XHouse2 with Bensonwood's engineering staff in preparation for this offering. The Bensonwood version of the house is subtly different on the outside. The front porch and rear deck framing is updated to be built with their timber-framing prowess. The wood cladding on the house reflects the products they have incorporated into their material stream. Internally the framing and details are completely revised to be built with factory made wall panels for a tight and energy efficient house. So although the design is clearly the same house, this is a unique edition you might say, only available through Bensonwood. Our house plan version remains designed for generic construction methods for the widest possible suitability. In fact its this generalized nature of my designs that allow them to be so readily adapted to Bensonwood's systems.

We're very excited to be able to offer our designs with such a high performance building system. Now you will find a new house plan group on our site for Bensonwood offerings, and the dedicated catalog page for the Bensonwood version of the XHouse2. From that catalog page you can click over to their site and land at their XHouse2 page.

Bensonwood will offer packages in different stages of completion from fully finished panels in their high performance Open-Built® format, to open framed panels only. This is a first step, although admittedly a small step, towards establishing a foothold for these new MMC/OSM manufacturing methods in the US. Look for us to expand the influence of these techniques in the future.

PreFab is Dead - When can we expect MMC/OSM?

For the past week I've been writing about what is wrong with PreFab in the US, and I've been writing about what is right about OSM in Sweden. The inevitable question is when will that come to the US? Is there anybody building like that now? The answer is while there is nobody working precisely as the Swedes do here, there is a builder who works with a very similar process, and even more importantly is an active student of Swedish and German building techniques. That builder is Bensonwood out of Walpole New Hampshire and we've just begun to offer our house designs built by them. But before the big announcement, let's look at what they are doing.









There are a number of US builders that have imported the various machines that are like the ones used in Sweden and in Germany, and they have used them for fabricating houses in panels - panelization as its called. But these builders do not attempt to finish their walls on both sides. Few even attempt to finish them on one side. Hence much of the great advantage of the technique is lost as a great deal of the work is still sent out to the field. There have even been attempts to import houses from Sweden, shipping them in their flat panel form to be assembled here in the States. A small quantity of houses were built and sold, but the designs of the Swedish houses admittedly did not make a clean fit to American expectations. For the most part the American housing industry has ignored Sweden's great achievement. A government funded report on the Swedish housing industry from the 1980s called "In From the Cold" documented the progress and results of the change to housing in Sweden. They presented this as a model for the US industry to follow, and then it largely fell on deaf ears. The researchers that conducted the study and wrote the report threw up their arms and moved on to other research topics. The few that have taken up some of these lessons have never carried them very far into the building process. They've done open panels, little more.



Bensonwood's journey into this was somewhat different. Coming from the American timber framing craft, Tedd Benson was quick to adopt computer driven milling equipment that he saw being used in Germany. This led him into the other types of automated fabrication techniques that were being used there, as well as leading him to be being present for the birth of the Passive House movement in Germany. Benson has been steadily taking this technology and the lessons of how they were building back to his shop in New Hampshire and evolving the way he builds homes here in the States. He's faced the same stumbling blocks that we've reviewed in examining the Swedish factory. Our building products here don't help you to panelize your walls, never mind make a high performance home. So along the way Bensonwood has been diligently adapting American products, importing european products where practical, and inventing what was missing, all in the pursuit of an intelligent manufacturing process. There is that word again! Intelligent! They have been connecting the dots where American component suppliers fail to, and building more and more value into their product. This is their form of MMC and OSM.







So where are they? Right now Bensonwood has several standardized wall and roof construction models that they can use to build a wide range of typical Amercian homes. Basically, if a home can be stud framed, then the Bensonwood system can be used to build that house. The system is offered in different degrees of insulation value to suit your climate, but it is worth noting that these can be used to build a home to a Passive House level of performance. Bensonwood calls their system Open-Built® and it supports the core philosophy of how they approach building homes. Number one the system is capable of very high energy performance. Number two it is configured for separation of utilities and structure, which allows the changes that happen over the life of a home to go on without interfering with the structure or spoiling the air tight envelope of the house. This supports Bensonwood's belief that a home should be built to last for generations.



The reasoning of Swedish factory builders is not precisely the same, but the prototypical wall construction in Sweden is very similar. Consistently they create an interior side chase space inside of the homes vapor barrier that allows wires, switch boxes, and plumbing to go where needed without puncturing the airtight envelope of the house. Bensonwood's Open-Built is the only thing approaching this offered in the US. There simply is no "PreFab" house that takes this deep approach to building science and performance offered in the US.





Bensonwood is also building with largely finished wall panels as the Swedes are, although they continue to offer partially finished packages for US builders that choose to finish the work themselves. However Bensonwood currently works their panels in a vertical orientation using a unique racking station that they've created themselves. Whether they transition to flat work like the Swedes remains to be seen. The process is ever evolving and there is always more to learn. The materials and finishes offered by Bensonwood reflect their New England roots, and as such the selections are extremely high quality and consistent with the high quality of their product.



We are excited to begin offering our house designs through Bensonwood, built to their high standards. We believe this opens up an entire new opportunity to our customers who are very interested in energy performance and the concerns of a sustainable and green home owner. Up till now the only option for people who liked our designs were our house plans. Out of necessity these are very generalized when it comes to performance. They are designed to use the most common construction materials, to make them easy to build, and build-able over the greatest range of locations. Bensonwood's offering opens up a new market for those interested in our designs, but seeking the best performance they can get. The universality of our designs make them readily adaptable to Bensonwood's building systems. We are really looking forward to seeing them build your LamiDesign modern house.

PreFab is Dead - Long live MMC and OSM

This is going to be the mantra: MMC is Modern Methods of Construction. OSM is Off Site Manufacturing. PreFab just does not cut it because transposing conventional construction activities to under roof is only a tiny step towards removing inefficiency from the building process. So much more can happen, and it can all build value for the customer.







So what happened in Sweden? We've gone over many of the details of how their building practices differ in prior posts. But what happened that enabled them to get to this point? In our LamiDesign Idea Log we've been posting images of Swedish Catalog House designs that are Modern. We've posted dozens so far, and there are more and more and more to show. How is it that a small country like Sweden can offer such a range to a market of limited demand like Modern? Yet here in the USA our larger merchant builders can offer none? Even if the percentage of buyers interested in modern in the USA is less than in Sweden, if you added them all up it would be larger than the entire market for the whole of Sweden. Yet our builders here can't even address this market with a single viable product? Not one modern house offered by the big builders that represent the majority of our market. Can you grasp the enormity of this failure?





In the late 60s and early 70s energy prices were rising worldwide. Sweden made a holistic overhaul of their building practices at this time to raise the energy efficiency of the homes they were building. There was cooperation between builders, labor, manufacturers, and the government to make this happen in a short amount of time. The results of the effort are impessive. Imagine that the winter climate in Sweden is much like Maine or other northern states. Yet the homes built in Sweden use less than half the energy of homes built in the US. They don't do this by turning down the thermostat, or curtailing the area of the home they heat. They have higher indoor temperature expectations than we do, and still they use less energy. Homes in Sweden are not viewed as stepping stones to bigger homes. While this remains a cultural difference between our countries, it gives them a commitment to make each home of high quality, including its energy performance. Prior to this push Swedish homes were built with wall construction of R18, and ceilings/roofs of R24, not too far from what we produce in the USA today. But today in Sweden standard walls are in excess of R30 and ceilings/roofs in excess of R40, and these gains were led by the industry and by market demand - not by building codes.



The factory building practice in Sweden has been driven partly by their short building season, but also by the gains in efficiency that have been developed in their factories. Housing is treated as a product, and as such every aspect of the design is rationalized into a know quantity of work, material, and ultimately a known price that is both profitable and viable in their market. During the time their industry was reinventing itself the various products and fittings that go into a house were all revised, improved, and updated to integrate into this industrialized process. Contrast this with our country where almost every home is built as a unique event on each site. Some industrialized components go into them, but for the most part each house is custom built even when the house next door is identical. Yet Sweden can offer its customers a more "custom" home buying experience than US consumers have. The computer driven fabrication tools they use give them great flexibility in their offerings. In the US if a buyer wanted a modern house in a development, the crews would have to reorient themselves to a new house design, building it once, and losing any speed they gained from the repetitive houses on other lots. That modern house of the same size will cost that builder more to build, and it will take longer too. They simply won't do it. In Sweden all they need to do is roll out the digital files for the requested design and set in motion the process to build the customer that modern house. Same process as the other houses, and the same cost. Its Customer driven.



The level of flexibility inherent in the Swedish housing industry is just not present in our so called PreFab industry. A typical modular builder in Pennsylvania has moved the construction process indoors, yes. They've avoided weather, and gained the benefits of working in a central location. But they are still framing walls as they did in the field, building boxes, and completing them in a similar sequence as site building. Wall frames are tilted up into place, and ladders or scaffolds give the workers access to all the vertical work needed to complete the modules. Insulation, sheathing, cladding, drywall, all applied on the vertical, just like building in the field.







Lets contrast that with a typical Swedish process. We'll even look at a Swedish modular builder to emphasize the difference. Walls are quickly framed up by automated machines being driven by digital data. Sheathing and cutting out of the window openings again are all automated. Siding is applied by an automated machine as the wall panel rides down the line, and its even painted on the flat. Finally the entire wall panel, with drywall on the inside, painted siding on the outside, windows all installed, is lifted on to the floor panel to make the modules. Joints closed, and the interiors finished. But nobody was up and down a ladder until the modules were formed. The walls were done when they went vertical.







I'd like to continue to just be very instructive about this, but at this point one really has to ask what the hell we are doing here in the US. It seems we are playing prefab house building like so many children with cute tool belts around our waists. Meanwhile the Swedes have created an intelligent industrial process, one that builds houses with precision, that ensures a tight house and improves quality, and provides reliable cost and schedule while making a far superior product. This is a MODERN - as in it is driven by contemporary industrial techniques and processes - METHOD - meaning somebody has thought about what we are doing, and ways to remove waste and inefficiency from the process - of CONSTRUCTION - meaning in the end we arrive at a house, the same goal as PreFab, but so much more calculated and precise. This is OFF SITE MANUFACTURING - here it is important to distinguish this from construction. We are not doing off site construction, right, because the Modern Method of Construction is MANUFACTURING, not construction. Manufacturing takes forethought. It takes planning of process, and planning of material streams, and waste reduction. Its not just the dynamic of building the house, but the designing and implementation of the industrial process to build houses. This is why PreFab is Dead. This is why MMC and OSM are our future.



Holy Crap, that sounds difficult you say - we have no idea how to do that. Just let us take our hammers and ladders and go back to the construction site. No no no no. The amazing part is that somebody has already figured this out. We don't have to start from scratch. We don't have to reinvent the wheel because the Swedes have already done it.

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A short addendum, just to look at the window installation from these two videos.







Here is our American friend hoisting his window into the window opening - his poor back! The wall is done, its already covered with house wrap. The window goes in from the outside, so he is reaching up over his head to put this in place. He'll be up the ladder in a few minutes to put a gang of screws through the "nail flange" of the window frame. There are no adjustments, you get it straight and screw it in. Later they will come back and put spray foam into the gap between the window and frame, or just stuff loose insulation into the gap.







Its not this fellow's fault. This is the way windows are installed in the field, and its the only way mainstream residential windows are made in the USA. So lets look at our Swedish friend. He's working on a table, with all his tools around. He does not have to carry each window to its location - the work is basically coming to him.







First he installs a butyl gasket all around the perimeter. No caulk gun or spray foam - this is a permanent gasket that will outlast any caulking or flashing tape. Then he installs the window into the framing - that's right - the window is installed before the wall is framed up. The assembly he is working with is the jamb studs, sill, and header, so he is able to square the opening before the opening is screwed into the entire house where if its crooked, its going to stay crooked. The studs and window are introduced into the wall framing at once just as the next stud down the wall. The Swedish window is mounted with six adjustable fasteners that allow the window to be adjusted once installed so even if there is any movement down the line it can be corrected - no call backs. This is analogous to the adjustments in cabinet hinges that allow you to square the door. Not only that, but the window can be easily replaced without tearing out subsequent work.







So our Swedish friend did not waste any time on a ladder. Nor did somebody have to comeback and seal up the window after it was installed. And its saved time down the road if the window needs to be adjusted, or replaced.



This is what we are getting at here with MMC/OSM. Every part anticipates its place in the overall assembly process. The American window at best has done a decent job of figuring out how to take their product and screw it to sh-t. You want to screw that baby down - we got you covered. You want us to seal that window for you, or let you adjust it if something got out of square, or make it easy to replace if somebody dropped a hammer on it. Well sorry bub, you are on your own there. These small steps not only save time in building the house, they improve quality, and they deliver more value to the customer. Get it?