1st floor extension - SIPs vs builder

[Adam_R]

Good Afternoon all

 

Been directed to this forum by my father who found this community very helpful when undertaking their self build a couple of years ago and he thought someone on here can offer some words of wisdom. 

 

We live in a house that was built around 1940s, it is a semi detached house with attached garage to the side. All 4 outer walls are brick with the inner walls being dry wall. This leads me to believe that the roof is bearing all the load on to the inner skin of the outside walls. 

 

We have received planning permission to extend out over the top of garage and kitchen, in essence expanding the upstairs 'box room' at the front of the house and put a double bedroom with a small ensuite at the back. 

 

Has anyone else had past experience of SIPs vs builder when doing similar work and care to share your experience and wisdom? Its a big outlay for us and want to ensure I don't regret going down the wrong path! 

 

Thanks in advance

Adam

[markc]

The roof should be supported by the outer walls, rare to find a house of that age that doesn’t have solid internals around stairs etc.

as to the sips or builder, I’m guessing you mean sips or brick/block for the extension walls as sips panels would still require a lot of traditional builder work.

in your case, as an extension requiring tying into the existing it will be much easier and cheaper to stick to traditional building methods … I.e brick and block.

[Redbeard]

...and if you want to go for 'woody', I find it a bit hard to see how SIPs (with some inherent thermal bridging AIUI) is much better than a TF and fill of your choice. Do you mean you would DIY if you did SIPs? You could also DIY a TF. I did my 'design', got SE to 'prove' it and off we went.

 

 

[ProDave]

Most modern TF construction, the inner frame supports the roof and the outer brick / block or other is decorative / rain screen.

[saveasteading]

Agree with all the above.

Sips is best in an open space,  not well suited to fit to an existing building.

I'd be interested to know what attracted you to consider sips.

[Adam_R]

I can't seem to edit my original post, so I have attached our drawings. These are the approved drawings so I have to go with timber frame upstairs. 

 

Hence the query of do I go with a builder who will build a timber frame or go with a SIPs specialist? 

 

[saveasteading]

I can't think a sips specialist will be interested due to size and precision.

[Rmjw84]

Hi, we are in the early stages of an almost identical project. Someone asked me today if I had considered using sip panels, so here I am! I’m curious to know what your final decision was if you have made it.

[HughF]

Brick/block makes more sense here…. Easily available materials, easily understood, easily tied into existing structure.

[kandgmitchell]

I guess the OP is trying to avoid the problem of supporting the inner leaf of a cavity wall along the line of the flank wall of the existing garage. The outer leaf will be built up off the garage wall but the cavity and inner leaf will be hanging in the air. That'll involve a beam at floor level that needs supporting or digging the garage floor up. Be also aware OP that you're close to the boundary so consider the unprotected area and spread of flame issues for all that timber weatherboarding/timber frame.