Pre-fab housing -- why not?

Referencing my post here of a few days ago Yankee Blogger wonders about prefab housing:

"What I wonder is why is that prefab is not more common. We all know that when you are going to buy a car, a dishwasher, a fridge, or most any durable good you go to a store, pick out the model designed by the manufacturer and produced in a factory with precise division of labour. It has been this way since Henry Ford started rolling cars off the assembly line. It has changed a bit since then, with cars being available with lots of options, lots of models, and lots of colours as opposed to Henry Ford's "any colour as long as it is black." But the fact is that it is cheaper to do manufacturing in a central location with each person doing a specific task repeatedly. It is also produces goods of a higher quality. Yet, the housing market has never adopted this model.

Here's my take, based on limited experience maybe 20 years ago in using modular housing.

First of all, just so people know what a "modular" is, do you remember those boxes floating down the Interstates, usually with a car-flashing-yellow-lights in front and behind? Anyway, that could be a "modular" or it could be a "mobile." The difference, 20 years ago in Washington State anyway, is in the construction method. "Mobiles" are typically built on a steel frame, "modulars" with wood and set on a concrete foundation. Mobiles are cheaper, less solid, just generally a more down-market product. That's nothing inherent, btw. That's just a marketing choice. (You could have a Ralph Lauren Polo mobile and it would be pretty nice, though the issues I deal with below would by no means be resolved.) Modulars are made with stick construction identical to a site-built house. In fact modulars are probably stronger as they have to withstand the stresses of being picked up by a crane.

Anyway, to the real point: why wasn't Bucky Fuller correct and why hasn't factory-built housing taken the market by storm? This link on Factory-Built Housing has some good background on the subject and reminded me of my own youthful questions:

WHEN I WAS A COLLEGE STUDENT struggling with an architecture major, I attended a lecture by Buckminster Fuller, inventor of the geodesic dome. "Does anyone know how much this building weighs?" he asked, looking up at the huge concrete gymnasium where we sat. If this were an aircraft, an aeronautical engineer would know the weight down to the last pound, but architects continue to design buildings as if the earth had unlimited resources. Fuller was convinced the earth could provide more than enough for everyone if we would only use its resources wisely and efficiently.

And so am I, but I am dubious that factory built housing is part of the answer.

I have several responses to Yankee Bloggers question. For one thing don't underestimate the size of the mobile/modular market. Its actually pretty big. One trade group says here that "[m]anufactured homes accounted for nearly a quarter of all new single-family housing starts during the 1990s." Many of the people who read this blog may simply not know people who live in mobiles (said with a long "i"). Or they probably wouldnt recognize a modular since a well-sited one will simply look like a nice rambler. But prefab housing is not, by and large either urban housing or multifamily housing. It works well on flat sitesm though.

The big issues are interrelated: money, flexibility, value, investment and "what business are you in." (And remember this is based on my own personal experience at least 20 years ago and with virtually no new information added since then; everything may be different now.)

1. Money Modulars, in place as a finished product, are simply not a whole lot cheaper than site-built houses. A great part of the cost of a house is in the land, the site improvements (sewer, water etc), and, for both builder and buyer, financing. As I think would be obvious to even non-builders, modulars have absolutely no advantage in any of those areas, except for some savings in construction interest because of the slightly quicker construction cycle. But that time advantage is eaten up by the very long time it takes to get permits for almost any housing project so the slight marginal advantage is really slight. The materials --- wallboard, paint, carpet, doors, windows, appliances etc etc --- which go into a house are going to be the same, no matter where you assemble them.

2.Flexibility At least in Washington State, (and espresso-tax aside, we are pretty straight-arrow and so I suspect that most States are the same) the administrative responsibility for certifying the construction of modulars is at the State level. No strolling down to the local building department. That means that in order to change the design of a house, say moving a window a few feet one way or another to emphasize or avoid a view or avoid, you have to run the plans through a state-level bureaucracy. No big problem there, but wait until you get on the site. In a topographically-varied area like Seattle (hilly!), it is useful to make adjustments to the design during construction. No thats not a great idea but it is a reality. Speculative builders work from standard plans and inevitably adjust the plans to fit the site. Its more cumbersome to do that, especially when with a modular you are essentially starting to remodel a finished house ---painted wallboard, carpets wiring in place etc etc --- if you want to make any changes. So it's my contention that the onsite adjustment of a design to maximize the utility and delight and hence value of a basic house plan is an integral part of the building process; t is humanly-impossible for a designer no matter how talented to be able to foresee every problem or opportunity on a particular site. So you have to bring them in to make site adjustments. But you can't do that easily with a modular, much less a mobile.

3. Value In a topographically-varied area, the way to make the house most valuable (thats better for both seller and buyer) is to make sure it fits the site as best it can. That means fine-tuning the design onsite. The inflexibility cited above turns into a limitation on maximizing value. Btw, if I remember correctly, Christopher Alexander supports such onsite design and suggests that the best structures emerge out of bringing together designer with builder(s) onsite to actually design the structure. I don't think a commercial, speculative home-building business could suffer such wild informality. But it's certainly an approach for certain clients. And if you don't make such subtle or even major changes onsite, you lose value.

And from the point of both the builder, buyer and society-at-large, we should aim to create houses and neighborhoods with the greatest long-term value, places where our heirs 200 years hence can look at what weve built and say You know, they did a nice job. That doesnt preclude factory-built housing but it puts a premium on maximizing the value of every site.

4. Structural investment If you are going to build prefab, that implies you are working offsite, which means you have to buy/rent real estate elsewhere. And you need a factory building within which to satisfy this decades-old dream of extruding shelter from the end of an assembly-line. That all requires a substantial fixed-investment. The elegantly-efficient home-building system which we have in the US is both very low-tech and very-low capitalization. It is an easy-entry/easy-exit business. A builder with a pick-up truck, a working foreman, and a secretary-bookkeeper can build 10-15 houses a year with no problem, which may not sound like much but it adds up. And if you are talking about a production builder who is dealing with plats of 50-200 houses (or even greater --- some of those california projects are huge) you start to create a factory the very site itself. In general, for both large and small builders, the construction site is the factory. And when local market conditions decline, the builder can scale-back the business simply by buying fewer lots or slowing down the rate of production. A manufacturer has a much larger fixed investment to keep feeding. The way we do it is very simple but elegant.

5. The nature of the business Ultimately, the house-building business is an adjunct of the real estate business, not of manufacturing. Spec builders produce a complete package of land and building and now "lifestyle." They have to be tuned into subtle local tastes. One business implication is that if you are a builder then its smarter to invest in lots ("inventory") on which to build a whole finished real-estate product rather than to invest in a factory through which to build just structures.

Anyway, none of this is to say that factory-built housing is not a significant part of the American housing scene --- it is in certain situations --- but simply that there are reasons why it has not been competitive in creating lower-cost and/or better designed/constructed houses than one can do on site using the traditional American home-building business methods.

(And if someone wants to condemn that very structure as the root of the problem, let's remember that going back at least as far as 18th century Bath, England, the profit-oriented spec building has been able to produce terrific neighborhoods --- by any standard --- and which grow in value every year.)

But thats my understanding of why prefabbing isnt real big in settled urban areas. The basic upshot as I see it? "Housing is simply which lends itself to extrudsion from a factory."There may have been some other points which I observed in the course of working with modulars, but that was a long time ago and I don't remember all the subtleties.

Comments

[Murph]

Seems like the second half of the "structural investment" section is the most important part of this post. Friends of mine who have recently bought first homes in subdivisions were able to pick a lot and to pick a floor plan (out of three options) and then a house was cranked out. There have been proposals recently for _3000_ unit developments outside of Ann Arbor, and I assume they'll be similarly giving a choice of 3 or 4 floor plans to their buyers. At that level of duplication, it seems as though "building" a house turns into "assembling". Model T's are movable, and so can be plopped on a conveyor belt and moved past the workers; houses are a bit harder, but framers and plumbers are mobile, so you just have to switch which component of the assembly line is moving past the other.

[JRoth]

Like so many architecture firms, mine has recently embarked on the quest for affordable housing through factory construction. Briefly, here's the view from the front:

Much of what you outline remains true. However, the industry has grown quite a bit in the last 20 years, both in size and sophistication. One effect of this is that the investment issue has faded - the base costs really are quite low, if you can work with an existing manufacturer.

Construction techniques are, I think, better than they were 20 years ago, and now compare favorably (to say the least) with site-built. Indeed, one of the main reasons we are pursuing this track is that we can now spec certain high-performance/green technologies at no cost upgrade - 2x6, ultra-tight construction are the rule.

We're doing urban infill housing, so the custom-window-location thing isn't really an issue. But we're able to do as few as 3 units that we design & they build, pretty much entirely custom, and the savings are significant.

At least on paper. I'll let you know in a year or so if this works out the way we think/hope it will. But for us, at least, the picture seems brighter.

To be clear, though: your general point stands, I think. Manufactured housing as the rule, not the exception, will I think always be the case. Americans, especially, are too hidebound about their homes to accept some of the tradeoffs associated with really large-scale modularized housing.

[Rich]

The reasons, taken together make a lot of sense. There are some reasons which involve the state skewing the market (regulations being at a state level) and some are just market forces. I always assumed that a factory would be cheaper, but you are right to point out that the flexibility in the construction labour market is of huge value to keeping costs low on site. Another thing to add is the cost of transportation. Due to the size of modulars they do not lend themselves to easy transportation (see the need for an escort pick-up), while wood, sheetrock, pipes, wires, etc. are all easily transported on rail or on truck.

And while variety in housing stock can make a neighbourhood more interesting over time, I don't think anyone has ever gone broke over-estimating the desire of Americans to sacrafice the integrity of their built environment for some short-term gain in convience (see the mini-mall, the mega-store, the subdivision, the parking lot, etc.)

[Fmstyle]

Hi, As student in architecture I like new concept and design. I find a idea very interesting. we have to admit that what first got us into the idea of prefab living was the prospect of never being able to afford to buy a house in New York City. We figured the only way our dreams of NYC(or somewhere else) home ownership would ever be realized would be if we could lease a high-rise rooftop and then stick a little prefab on top. Now, The $136,000 Loftcube, which we’ve featured before on Inhabitat, is a cheap and cheerful little prefab house designed specifically for roofs. I have photos on mu Blog, Have a look. http://nat-envir-sun.blogspot.com/

[Modern Prefab Homes]

We live in Hawaii, where construction costs are through the roof, and builders are as likely to go surfing as show up for work. The biggest advantage of prefabs to us is speed of construction. Many of my friends have been building their dream homes for several years as building supplies are scarce and shipping costs outrageous;) Additionally, our architects can't seem to get away from the plantation-style, pitched-roof tract home look. The new contemporary prefabs are gorgeous. While the prices are about the same, I think factory construction is superior to local built (at least here), especially with regard to insulative qualities, and green building practices.

[Schumacher Homes]

Custom built homes are the best way to go in my opinion. That way you get exactly what you want from your new home and you won't need to spend all of that extra money on remodeling.

[Schumacher Homes Press]

Custom built homes are the best way to go in my opinion. That way you get exactly what you want from your new home and you won't need to spend all of that extra money on remodeling.