Why hasn't prefab construction taken over?

It's about scale, as the person you are responding to clearly said.

Technically, it might be a win. It's not enough of a win, however, to bring many new converts. It simply doesn't scale to enough large savings to make much of a difference in the construction budgets OP actually was writing about.

standard stick built has a lot of things already factory done. most lumber is a standard length/width, and the entire print is built around those sizes. 2x4s come factory cut to 92 5/8 long, which (after adding the other lumber needed for a wall) leaves a finished 8 foot wall ready for 2, 4 foot wide sheets of drywall.

What labor is done on site in a typical stick built construction project is mostly the same manual labor that needs to be done in a factory. Which isn't surprising: construction sites are just mobile factories for buildings. When you have to make something with lot of empty space is makes sense to ship the factory to the final location.

Shipping is a factor too: a stick built house arrives on one flatbed truck. A similar prefab house needs 3, and special permits to get it down the road (which includes checking for lower hanging power lines).

logs are poor insulation. The definition of R1 is a 1 inch board. normal 4 inch walls are r13, the log is 4.

I built my current house recently, and our builder used a prefab factory in the region for some of the construction. I would _never_ do it again. The process has all the pitfalls of the waterfall software development model, but at the end you have to live in the failed project!

It took months for the factory to do their pre-build engineering, and that's after they started the process using plans from my architect. The companies building these modules tend to sell mostly from their own catalog of floorplans and modules, so they don't have a strong incentive to hire skilled architects for the relatively small amount of custom work that comes in (I fell into this category). I'm led to believe that they hire draftsmen instead of architects.

They built one of the modules a foot too long, so it hangs over the edge of the foundation. They also messed up the roof line, so some guttering and geometry had to be changed for the garage that was stick-built onsite. They did all of the drywall wraps around the windows incorrectly. Every single door was hung incorrectly, some with chunks taken out from bad routing. The vinyl plank flooring has bubbles because they didn't float it correctly. They omitted electrical features that were on their own drawings. They ordered a few wrong windows, so they charged me anyway and just laid them on the floor when they shipped the module.

It'll all be fine at the end of the day, but the parts that were built onsite are all so much better. No cheaper, mind you, but faster and with much less drama. Maybe there are some parts of the industry that do a lot better, but I kind of wish I'd listened to my dad when he said "the pioneers take the arrows".

10 years ago I purchased a Maronda homes in a yet to be developed housing addition. I was able to watch a lot of homes be built using there construction method of pre-built walls/floors/roof lifted via crane. It does seem like a great idea, speeding up onsite building, and preventing the wood from being left in the elements. These benefits appear to come at a cost.

a) The largest benefit seems to come when building a similar building each time, any changes make it hard for the crew to assemble.

b) The site has to be cleared of trees and rather open to allow access of the crane.

I have since moved to a hot housing market in New England, and see many lots leveled and replaced with new homes. All of them are stick built on site, and this doesn't appear to be an issue. The number of days for an experienced crew to stick build a house is short, and many of these homes are very custom. The site/house is normally optimized to get the largest sale value, not the easiest built. The other interesting this is it is generally impossible, or not cost effective to use a crane to lift parts on many of these lots. Even if having pre-built sections is a cost savings, it would be such a small difference it wouldn't be worth it with the possible risk of quality of the pre-built items and/or timing of construction. Home building is a complicated process and many companies seem to be providing solutions without looking at a total solution.