So the question was raised and I think this topic is critical. Some will have their own experience building a SIP house, some will only have an opinion. Its probably also a question of what do we compare... SIP house and conventionally build to-code-min timber framed house?
But bottom line... is it more expensive to build with SIPs?
Plumbing should really be in about 20-45mm cavity under plaster board. On top of SIP surface.
Quick answer: the plumbing pipes shouldn’t be in the same layer as insulation layer, simply becomes it compromises performance. The fact that we are used to doing plumbing in external walls doesn’t make it the right thing to do. As inter tenancy wall there is less benefit in using SIP. And if you can’t get plumbing into suspended ceiling or floor cavity or even other internal partition walls, maybe you shouldn’t use SIP for IT wall... to save space...
Does the use of sip like formance reduce the internal space? Does the firewall need to be thicker than stick frame? Im convinced its great but the plumbing also needs to be boxed inside, occupying space. Can you please tell me how i can use sips where it doesnt occupy more soace than stick frame as the terrace houses i intend to build are 4.3m or so wide
From what I have seen being tested for Fire and Acoustic... one 115mm wall with layers of plasterboard each side. Benefits of SIP as internal wall are mostly in airtightness between units, and speed of construction.
Im about to build 6 terrace houses with inter-tenancy walls. What size walls do you suggest i use?
Here is a link to an article about the value of the energy efficient houses when they sell..
After designing and building a couple of SIP homes I think I did come to some conclusions.
Even just 5 years back it was a bit of a task finding a builder that is happy to try new product. I think it created a bit of a false opinion about the cost of SIP homes. But things changed and there are many builders seeing the benefit of a predictable and accurate build, that also results in higher quality build that builders can be proud of. So thats good, comparing the costs is now a little more accurate.
When it comes to material cost I guess things change every year, sometime couple of times a year. Timber price changes, shipping and transportation costs etc..
Another important aspect is selecting the build systems that are worth comparing. Do you go with basic 90mm framing and code minimum insulation, compared to thinnest SIP panels available? These two systems almost shouldn't be compared, the SIP will outperform the framing by so much, it doesn't make a fair comparison.
But what I mostly see is people comparing the cheapest possible options. And if you did... SIPs would probably be more expensive. But if you spent a couple of days living in a SIP home... I don't think you would even consider the framing option.