insulated timber stud wall back boxes

[sweeneyuk]

i have built a stud wall out of 3x2 & plan to use 50mm celotex/kingspan insulation in between frame work before vapour barriering & plasterboarding.

my question is how do i mount the back boxes for the light sockets & socket outlets?

Do i use a plasterboard back box & hack out a hole in the insulation?
this will hole the vapour barrier & be a cold spot.

Do i chisel out just enough of the insulation for the box to sit flush?

both these methods will mean i'll have to precut a hole in the plasterbord before hanging it on the timbers which may be difficult.


any advice on whats best to do?

 

[ban-all-sheds]

You need to make the wall thicker. Where is it anyway? Surely 50mm of insulation won't be enough for an external wall?

You need to create a void between the vapour layer and the plasterboard which is big enough to contain the services. Any removal of insulation will create cold bridges, and any perforation of the vapour control layer will create condensation problems.

If you can't make the wall thicker then you can't have wiring and accessories in it.

 

[PrenticeBoyofDerry]

or use surface mounted accessories.

 

[holmslaw]

..

 

[ban-all-sheds]

Need a void for them to go into.

 

[holmslaw]

..

 

[ban-all-sheds]

Maybe, but not necessarily - it depends which way round his 3x2 is, and where the insulation is in relation to the boarding. Need more details of the construction basically....

 

[holmslaw]

..

 

[sweeneyuk]

my 3x2 is about 20mm from the wall at its shallowest. built it because the wall was in bad state & very uneven. also wanted to add insulation.

so if i push the insulation right back should = 75mm + 20mm void - 50mm kingspan = 45mm + 12.5mm plasterboard.

can i push it right back to the wall?

Also my jeating pipework is behind thestud wall & so it will be in the void & come through the insulation & vb.
should i get this changed to bring it inside or although its not adeal can i leave it as is to save money?

whats a good vb to use & where do i get it?

 

[ban-all-sheds]

More bollerx from bas.

Care to provide a rational explanation showing why it would not be possible to use 2 x 3 timber to build a frame either 2" or 3" thick?

 

[ban-all-sheds]

can i push it right back to the wall?

You might do best asking on the Building forum. AFAIK you can push it right back.

Also my jeating pipework is behind thestud wall & so it will be in the void & come through the insulation & vb.
should i get this changed to bring it inside or although its not adeal can i leave it as is to save money?

Absolutely bring them onto the warm side, or you'll be losing money by losing a lot of heat from the pipes. Remember that once that insulation goes up they won't be in room temperature air they will be in cold air.

Also if you leave them where they are you'll have to deal with them perforating the vapour barrier.

whats a good vb to use & where do i get it?

Building forum again, but have you considered products like Celotex GA3000?

 

[ColJack]

if you only want a 2 inch thick "partition" then you buy 2x2 and save some cash..

 

[sweeneyuk]

okay i need solutions for what i have already. baby on the way & money tight.

the stud work is 3x2 & i'm not ripping it down now.

i've moved the electrics into the front 20mm of the studs/ noggins.

plan to move the heating pipes too.

regarding the vapour barrier, i believe some celotex insulation incorporates the a vb so will tape around the slabs & wood framework with vb tape. also will use duplex foil back plasterboard.

this is as good as i think i can get it short of starting again.

any ideas on whats the best insulation to use between the studwork that incorps the vb?

also where is cheapest to buy?

cheers

 

[ban-all-sheds]

Celotex and Kingspan and Knauf have a wide range of products, websites full of technical info to help you decide which one is best for you, and are on sale all over the place - just start googling and comparing.