Timber frame on top of single skin walls...

[rick734]

Hello guys,

First time posting so take it easy! I've got a single skin garage on the side of my house, with solid foundations (BC happy with them) and walls seem to be straight and in decent condition generally. Hoping to do a simple timber frame first floor extension above it (timber frame because it's lightweight and can potentially do what I describe below, also relatively easy to build for me). A builder I've been talking to reckons that you can simply sit the 150mm wall plate timbers (for first floor timber frame ext) on top of the existing 100mm blockwork single skin, with the other 50mm supported by vertical timbers on the inside of the single skin - I guess you'd build it like a stud wall underneath the wall plate. Does that sound feasible/possible? I like the idea because I'm keeping it as low-budget as possible and it sounds fairly simple/low-cost, but

I can grab photos if that will help but there's not a lot to see ATM.

thanks

 

[Ivor Windybottom]

What's going to hold up the internal skin? That is the one that normally takes the weight of the floor and roof. The garage floor isn't sufficient.

 

[freddiemercurystwin]

I think the theory is to only have a single skin of timber frame sat on the existing brick skin, render or brick slips on a carrier board on the outside presumably, though they will overhang the existing outside wall face. You can build in single skin timber frame but all of this needs an SE to do some number crunching .....

 

[^woody^]

Typically you would sit/strap the floor joists onto the wall first and these would carry the wider frame. The frame does not need to be 150mm though.

Make the panels first, work to 1200 or 600 wide units wherever possible (including openings) and then just assemble them. This tends to avoid requiring the design to be proven as it's a standard detail if you use the typical sized components and fixings.

 

[Ivor Windybottom]

Oh, so just one timber frame with cladding on the outside and vapour barrier/plasterboard on the inside?

I get it. Like a caravan.

 

[freddiemercurystwin]

Rendering timber wall/frame

Hi, What is the most cost effective way of applying external render to a timber frame wall? If you can provide any links, that would be appreciated :) Looking at achieving a u-value of 0.3 for a first floor external timber wall. Thanks, Damo :)

www.diynot.com

 

[rick734]

Thanks guys and apologies for the delay replying - work rules!
I will be getting a SE on the job, but just wanted to get some ideas of what might work first.
Thanks @freddiemercurystwin and yes that is correct so thanks for clarifying. Bit of a pain about the overhang - do you know how much that would be? I guess something like 11m OSB, 25mm batten, 12mm render board, ~15mm render so perhaps ~60-65mm total overhang?

 

[rick734]

Typically you would sit/strap the floor joists onto the wall first and these would carry the wider frame. The frame does not need to be 150mm though.

Make the panels first, work to 1200 or 600 wide units wherever possible (including openings) and then just assemble them. This tends to avoid requiring the design to be proven as it's a standard detail if you use the typical sized components and fixings.

Thanks Woody, so effectively build the wall on top of the joists? I guess you could then move it inwards slightly as well, which might help negate or remove the overhang @freddiemercurystwin mentioned...
So you would literally just build a section of stud complete with insulation and outer boarding, and then add the VCL once everything's installed?

Interestingly BC did say that they would be happy without a technical design for my porch, which will be single storey, 150mm timber etc so I guess the same principle applies here..

 

[^woody^]

The frame would need to be flush with the wall below. The battens and cladding would project, as this allows for the vented and drained cavity.

 

[rick734]

Thanks that's really helpful