Prefab/SIPS extension

ma9gm

Hi, I'm trying to find the pros and cons to doing a prefab/SIPS extension. I hear it tends to be quicker and cheaper, but can't really find many places where there is a neutral review. Any views? What's the gains and loses on these bad boys? Any advice or ideas would be appreciated.

Doozergirl

I don't think SIPS are ever cheaper! The OSB SIPs have to be clad with something - it depends on what you have to match on the original building.

There are magnesium oxide SIPs that can be rendered straight onto.

We're planning to build our house with SIPs. The advantages to me involve the airtightness of the building as a whole, rather than an extension.

We've recommended a SIPs extension to people who have quite unstable ground. A raft foundation and a relatively lightweight structure we felt would be beneficial.

If it's a sizeable extension you're building, you may get some economy of scale, but I wouldn't expect it to be cheaper. There is off site manufacture lead in time to consider but it does take less time building on site.

ma9gm

Thank you for that. For some reason I was thinking it would end up being cheaper than a standard brick build.

So the main advantages are it's better to control temperatures and quicker to build?

Thank you

Glen

Ruski

The SIPS extension on a DIY SOS build that I was on recently went up in a day, was roofed and clad with cement board sheets the next day and then rendered with k-rend over the next couple of days.

Being of this type of build there was a LOT of labour thrown at it, and if I'm perfectly honest I still think I'd prefer a brick shell, but that's just my own preference

Was it quicker? Yes, just. Was it cheaper? Don't know, but there did look like a lot of materials and labour used on it.

HTH

Russ

Smiley_Dan

Don't like SIPs personally, prefer a timber frame or a single skin with EWI.

System

I've used sips a few times, saying it's a cheap way to build isn't necessarily true, it depends on the way you are building - for a self builder they are good because you can get wind and water tight incredibly quickly and you are only paying for a few days of skilled labour. I've used them where the weather was a huge issue so they really worked.
The roof space is also a big plus point.

The biggest concern I would have for an extension is that you're unlikely to have completely plumb junctions with the existing building and you regularly need to adjust things to match, so there's no huge advantage in having mm perfect panels...

bgm_co

We build a house with SIPs in 2010. Very quick and energy efficient, but cheaper? I would say certainly not.