There isn’t too much in the article about cost (“affordable” is vaguely mentioned in passing), but it seems like prefab isn’t generally cheap. Does anyone have any insight into why prefab construction isn’t much, much cheaper than a traditional stick build?
It just seems so obvious that it should be cheaper to do as much work in a factory as possible. Home construction seems like one of the few large industries still stuck in the time before the Industrial Revolution: work done by hand by a variety of highly-skilled artisans instead of mass-produced at scale.
Land isn’t the main driver of cost (unless you’re in one of a handful of ultra-desirable locations). Nor is the sitework or the foundation. From a few quick sources, it seems like the structural and finishing work (everything starting with a slab and ending with a finished house) is roughly 80% of the cost. This is exactly the part that seems like it could be done in a factory with a high degree of automation, like with cars and furniture and most manufactured goods.
I think it's just too little volume for the savings to trickle down. The majority of houses built today are still done in traditional ways, very few new homes are prefab homes (in the US and Europe). Most of the people buying prefab homes in these regions today are doing so because it's faster (weeks to months instead of 6 months+) or easier (only need heavy equipment on site for a couple of days), so those benefits can be sold as a premium service.
I am having a new home built right now, and the costs are roughly 50% for the 'shell', e.g. to the level where you have a water proof building with roof and windows, and 50% for all the work inside. For the 'shell' it's actually quite simple work, and doesn't take too much time, it's basically just LEGO :D The complicated parts like doors and windows are made off-site, so when they arrive you just need to fit the house around them. We are having a traditional A-style roof, so the roof joists are made off site too. Most of the costs are on the materials, not the work. Materials that reduce the work like ICF or SIPPs also increase the material costs - in my case to a point greater than what you save in labour costs.
For the interiors nothing can really be prefabricated at volume, as everything is completely custom to the project. That's not going to change unless these Japanese standard measurements that article talks about spread elsewhere. For large projects its a bit different though, I've heard for hotels they sometimes prefabricate large parts of the bathroom and lift it into place before the next floor is put on. That makes sense though as you are building a few hundred things that are exactly the same.
Most houses are done in a factory. When you build you don't buy the individual trees (except for log cabins), you buy lumber that was made to standard sizes in a factory. You don't get raw iron ore, you get screws and nails - both made in factories. The part that is done on site is not a large part of the total effort (well because of the efficiency of factories it might appear that way - but compared to the same without any factory)
What is done on site are things that people want to customize, and so there isn't must opportunity to standardize other than to make all houses the same which people don't like.
> There isn’t too much in the article about cost (“affordable” is vaguely mentioned in passing), but it seems like prefab isn’t generally cheap. Does anyone have any insight into why prefab construction isn’t much, much cheaper than a traditional stick build?
It just seems so obvious that it should be cheaper to do as much work in a factory as possible. Home construction seems like one of the few large industries still stuck in the time before the Industrial Revolution: work done by hand by a variety of highly-skilled artisans instead of mass-produced at scale.
Land isn’t the main driver of cost (unless you’re in one of a handful of ultra-desirable locations). Nor is the sitework or the foundation. From a few quick sources, it seems like the structural and finishing work (everything starting with a slab and ending with a finished house) is roughly 80% of the cost. This is exactly the part that seems like it could be done in a factory with a high degree of automation, like with cars and furniture and most manufactured goods.
What am I missing here?