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Comment by woah | Hacker News Reader

Seems pretty expensive to make everything out of pure plywood. Does anyone have a sense of how cost compares to 2x4's plus drywall? I assume either construction method will need exterior cladding and insulation.

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When I choose a concrete slab foundation, their price estimate tool gives me a range of £NaN - £NaN. Representing currency as a floating-point value strikes again.

Typical Javascript strikes again?

There's a lesson here:

Lay your foundation with strong types.

What type are you supposed to use to represent total cost when spending infinite money for 0 days?

It seems the Romans took their concrete type secrets to the grave.

https://www.archdaily.com/875212/scientists-uncover-the-chem... :)

Modern concrete with superplasticizers is far superior to Roman concrete.

The greatest limiting factor is not the concrete itself, but rebar. It will eventually rust, causing the concrete to spall and crack. So in most cases it makes no sense to really optimize the concrete lifetime, because why bother?

If you're willing to build structures that rely only on compression and gravity, then we can totally do stuff that the Romans never dreamt of. Just look at any modern concrete gravity dam as an example.

In Javascript? probably a different type than if you took 0 days to spend infinite money.

You need refinement types. Psuedocode:

    timespandays : int, timespandays > 0

your program can then be proven by the compiler not to NaN.

The area defaults to zero, and recalculates when you change any of the parameters, resulting in a divide by zero and NaN being displayed

Since it’s a UK company/project they will be primarily comparing to brick costs since that’s what the vast majority of UK houses are (still) built with. They claim comparable cost as brick/block construction. £230/sqm.

They also seem to be touting their accuracy and since plywood is dimensionally stable (well, more so that 2x4s anyway) that’s probably why ply.

It's cut on a cnc router table, which does not handle regular wood very well. The dimensional stability and anisotropic nature of plywood is a better fit for most automated cutting methods. If you try to CNC route most regular dimensional lumber it has pretty bad tearout and splitting unless you use a really fine cutter and go slowly (which takes forever).

Is double brick still built in the UK, or is wooden framing with brick cladding more common?

Breeze block for the inner skin and red brick for the outer skin is still the standard as far as I see from local housing developments and friends doing extension. Internal dividing walls may now all be stud partitions but wooden structures are pretty uncommon.

> They claim comparable cost as brick/block construction. £230/sqm.

That seems quite unappealing for something with a certified life of 60 years (even if it lasts longer in practice, mortgage brokers won't be keen)

Oh man. To me this plywood stuff seems like it might be marginally more durable than 2x4 and sheetrock, or maybe not (worse ventilation etc). So to me it seems like they have just reinvented the American "balloon" construction system, but overengineered, and probably at much greater expense.

My rough estimate is around $4.75/sf for a high performance wall (drywall+2x6+osb+exterior foam ~ R31). They show £230/m2, so this product would be almost 7x more expensive.

Margin.

If they save time and provide convenience or reassurance, then they'll provide value for some people.

It remains to be seen what the demand will look like, especially given the heavily regulated market.

edit: the "Fit out & finishes" drop down really brings the costs up. I'm not so sure about this product after all.

Frankly there is zero way to bet a stud wall with a bunch of CNC'd plywood. The key is most of the wall is not made of the stud, plywood requires the entire sqft or m2 to consist of plywood.

In a stick built house you're paying a lot of labor. Material prices are not that much.

For example, the material list for a 3 bedroom house is 130k. https://www.menards.com/main/building-materials/books-buildi...

Say the land is 130k in your region. You won't find 3b houses for less than 360k. If you're looking at not so cheap builders, it will be 500k.

I think there's a revolution coming in the way we build houses, it must be - because costs are through the roof. It could be either in the form of prefabricated walls, like we have now trusses, or lego bricks like the OP, or something.

For stick frame houses, around 10-15% of the cost is framing. Finishes account for the bulk of the cost.

well yeah, because everything is so bespoke: plumbing, electrical, windows, doors, drywall, trimming. I hope to see some kind of evolution of housing where these things are not installed by skilled labor somehow.

It's the UK, so everything is twice as expensive anyway.

Not the Bourbon Creams at Waitrose. 90p? What a steal.

Custard Creams are 65p at Tesco, bargain of the decade

R31 exterior foam will rather outperform the WikiHouse blocks due to reduced thermal bridging. And you get a structure that is essentially immune to condensation damage, so you can skip the annoying interior vapor barrier and all the problems that it can cause all by itself.

You're correct - but wait until you meet their other friend "milling the panels." Doing it out of plywood is one increased level of expense and difficulty - machine and operator time is an exponential multiplier. Think about it - you're taking a system that could be a guy with a table saw ripping a piece of ply in a minute tops and turning it in to a guy standing and watching a mill run through a piece of ply in who knows how many passes... it just doesn't make any sense.

Not only that, but in order for the assembly process to work the modules must apparently be "fabricated to millimetre precision". At a certain point, wouldn't this inevitably mean that the QA process would result in some of the yield having to be discarded as unusable after it's manufactured? Seems like a lot of waste compared to conventional methods using (literally) run-of-the-mill lumber and someone's design expertise, though I guess the argument is that architectural expertise doesn't come cheap and using a "framework" scales better in that respect.

In a stick frame building, everything still gets clad with sheathing (plywood) and subfloor (thicker tongue and groove plywood).

Structural insulated panels (plywood/foam sandwiches) have been around since the 70s. They're a useful building technology.

There's no way they can provide an equivalent amount of product to a SIP cheaper. They're operating at small scale, and CNC machining everything which is expensive. The math ain't mathin'.

Isn't plywood cheaper than solid wood?

A 1x6 which is probably thicker is usually around $4-5 a 3/4 plywood at 4x8 is $51 ish, so 8*1x6 ($4.5 at 8ft length) = $36, and $51 for plywood. So no, plywood is not cheaper at apples to apples comparison. If you chop the thickness down you can get it to be comparable or cheaper. But plywood is stronger then a bunch of 1x6.

> A 1x6 which is probably thicker

A 1x6 is .75 x 5.5 inches.

Plywood is still more expensive with your numbers. OSB may cost a little less than the plywood though.

That would depend on the mill, you can get nominal and actual sized wood. At least I can in Canada get true 1 inch x 6 inch wood.

I think it has been for at least 30 years - perhaps longer. Structural beams were cheaper to make of solid wood when they were still lots of big trees to be had. That's no longer the case.

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