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Comment by albrewer | Hacker News Reader

I used to work as a framer during the summer when I was going to college.

What you're glossing over here is that about 10-15% of the timber you buy to frame a site-built house is wasted (ad-hoc cuts, bracing, jigs, etc.) and thrown into a dumpster.

If a house is pre-planned, you can use a machine that cuts each board to length, and join the ends of each board using basic joinery processes that aren't practical when building a site-built home. You can pre-fabricate things like trusses and wall segments so you (or your workers) aren't driving 100k fasteners to fabricate something a robot could build in 1/10th the time.

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I'm not sure recouping some of that wastage is worth the switch. You wouldn't eliminate all waste since there will always be some on site modification. I'd like to see the comparison in time spent assembling all of these individual segments vs framing a wall with an air gun. The segments look a lot more fiddly to me compared to laying out pieces on the deck and banging them together with a gun and then just standing the wall up. From their guide on the site:

> A typical WALL block weighs around 40-60kg and can generally be carried by two people.

They're a little light on detail about how these wall segments join and seal to each other so that could be a bunch more work. All this is considering you'd be able to get pre-manufactured blocks from somewhere, if you had to CNC and assemble them yourself then the labor is off the chart.

> If a house is pre-planned, you can use a machine that cuts each board to length, and join the ends of each board using basic joinery processes that aren't practical when building a site-built home. You can pre-fabricate things like trusses and wall segments

aren't prefab trusses readily available these days? i feel like i've seen plenty of trailers hauling stacks of 10 timber trusses down the road.

we've also got prefab homes (not mobile/trailer/whatever homes), with modules assembled in factories and brought together at the site. unfortunately they seem to carry class connotations here in the US.

A mate of mine used to work in a place that manufactured segments of regular wood framed houses. They had painted outlines on the floor, so they could cut and assemble 2x4 frames at great speed. I think you would need to make a truly massive number of these before a robot would be more cost effective. I also think that 2x4 construction would create less waste than parts CNC cut from ply sheet.

They exist and they can be designed to take advantage of things like making sure each room is designed to use full board lengths, no cuts (8 foot stud walls, for example).

yeah, prefrab trusses, prefab sip panels, modular houses, trailers and prefab houses divided up into rooms that can be trailered and joined onsite all exist

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