“Stud wall” type extensions

[Jupiter01]

My house is rendered externally. At the back, I have a lean-to tiled roof over my existing living room and kitchen. The kitchen backs on to the garden.

I would like to extend the kitchen but can’t afford the cost of a conventional structure: two leafs of block and potential redesign of existing roof. Given that the external finish is render, could I dig some foundations, build new walls with a solid stud wall frame which is rendered externally and hence, look the same as the rest of the house and put a nice rubber roof on it?

I can then insulate between the studs and may be add some more if necessary. I could happily to all this work myself.

Do building control support this type of approach?

Interested in your thoughts.

 

[frutbunn]

There's nothing in the B Regs to preclude it as long as it satisfies the Regs.

 

[mrrusty]

Why not look at SIPs - structural insulated panels. The SIP suppliers provide construction details that illustrate how to apply rendering and cladding, and they avoid the need to construct studding etc. As a pre-formed wall structure should also be easier to justify against building regs as all the data will be directly available for the panels. I've costed up myself, and yes building up stud walls yourself is a little less material cost, but would take a lot longer. e.g. https://www.sipsdirect.co.uk/

 

[^woody^]

It's caller "timber frame construction". It's the rage apparently.

 

[mrrusty]

It's caller "timber frame construction". It's the rage apparently.

No s*** sherlock! sorry couldn't resist...

 

[Jupiter01]

A lot of the SIPS material is behind a login.
At a simple level, is it a case of digging a foundation (depth?) for the studs to sit on, concrete it, place a membrane to protect the timber from moisture and the. Build up to plate level and pop a suitable roof on. A flat roof in my case. I could wrap it with OSB boards and roof membrane followed by moisture boards and rendering.

I’d appreciate if someone can validate the above or provide a steer on how this is approached.

 

[mrrusty]

A lot of the SIPS material is behind a login.

Y but you just register - accessible to everyone.

 

[^woody^]

A lot of the SIPS material is behind a login.
At a simple level, is it a case of digging a foundation (depth?) for the studs to sit on, concrete it, place a membrane to protect the timber from moisture and the. Build up to plate level and pop a suitable roof on. A flat roof in my case. I could wrap it with OSB boards and roof membrane followed by moisture boards and rendering.

I’d appreciate if someone can validate the above or provide a steer on how this is approached.

SIP is just a factory-made timber frame panel. Nothing else. It's not viable financially for domestic extensions.

Timber framed buildings need exactly the same foundations as masonry ones. You then make the frame, insulate it, add the sheathing to make it rigid, and then add the cladding to protect it from the weather - and the cladding can be fixed to the frame or independent of it like a brick wall.

 

[Nakajo]

It's not viable financially for domestic extensions.

This has been my experience too.

 

[mrrusty]

It's not viable financially for domestic extensions

I'll be finding out because I'm intending to use them on a 25sqm DIY garden room next year - priced up from sipsdirect, there is a premium over building up a traditional stud frame and insulating and sheeting it, but as far as I can see so far the premium isn't huge and the time saving factor, even DIY looks interesting.

 

[^woody^]

the time saving factor

I think it took me less than 20 minutes to knock up each of my 8x4 panels, and as assembly time will be equal, and each method still needs to be wrapped, the only difference is the massive extra cost of each equivalent SIP.

 

[mrrusty]

the only difference is the massive extra cost of each equivalent SIP.

It's not so massive. 120mm SIP is ~£100+VAT made up of 2 sheets of OSB + sheet insulation + stud frame or glue to hold it all together is ~£50-60. I'm only intending to use sips for full wall sections - I will fabricate gables and around windows. I can also use very lightly supported SIP roof which will reduce roofing timbers, so yes, the uplift will be in the low-mid £100s but benefits in quick and accurate construction. Still very much a work in progress, but the CADs I've just started doing are based on SIPs.

 

[Notch7]

My house is rendered externally. At the back, I have a lean-to tiled roof over my existing living room and kitchen. The kitchen backs on to the garden.

I would like to extend the kitchen but can’t afford the cost of a conventional structure: two leafs of block and potential redesign of existing roof. Given that the external finish is render, could I dig some foundations, build new walls with a solid stud wall frame which is rendered externally and hence, look the same as the rest of the house and put a nice rubber roof on it?

I can then insulate between the studs and may be add some more if necessary. I could happily to all this work myself.

Do building control support this type of approach?

Interested in your thoughts.

I designed a project just like this for a friend.

It's worth having a look at the tyvek site which have some downloads of construction details for timber frame.

Externally the studwork gets covered in breathable membrane, then vertical battens, then rendaboard.

The detailing is very important in timber frame construction....damp, vapour etc