Ask The Trades - Print Page

Ask The Trades
https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> UPVC Cladding https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1236531234 Message started by simonsays on Mar 8^th, 2009, 4:53pm

Title: UPVC Cladding
Post by simonsays on Mar 8^th, 2009, 4:53pm

I am building a covered side entry to my property.

The outside face will be tight adjacent to a timber featheredge fence. I am cladding the outer wall with 10mm upvc. The question is, do I need to use vapour barrier between the upvc and the insulation? I know upvc doesn't breathe so does it matter?
Cheers
Simon

PS. Great site by the way!

Title: Re: UPVC Cladding
Post by big_all on Mar 8^th, 2009, 10:45pm

i would think it advisable to have membrane and the usual air gap
incase you get a leak as theres no g'tee that the cladding will remain water tight
whats the structure behind the cladding!!!

Title: Re: UPVC Cladding
Post by simonsays on Mar 9^th, 2009, 1:32pm

The featherdge is my boundary fence. I am building right up to it.

I think I will go for vapour barrier, just incase!

Title: Re: UPVC Cladding
Post by big_all on Mar 9^th, 2009, 6:04pm

ok i ment the internal structure between you and the cladding!!! ;D ;D

Title: Re: UPVC Cladding
Post by simonsays on Mar 9^th, 2009, 11:38pm

Sorry sorry, just me being dim.

I am covering in the side entry of my house. 3 brick high wall on 3 sides and then a stud frame to make up the rest of the height, I am cladding it in UPVC, hence the question about vapour barrier. It will be isulated etc, but still not sure about the vapour barrier.

Thanks

Title: Re: UPVC Cladding
Post by woodsmith on Mar 10^th, 2009, 7:36am

Vapour barriers sit on the inside of the insulation and prevent warm moist air from inside condensing on the cold inside face of the outside covering. What you are talking about is called a moisture barrier and works in a similar way to roofing felt.

If I build a timber frame wall starting from the inside,

plasterboard

vapour barrier, (polythene sheet) or can be incorporated in the plasterboard if you use the foil backed type

stud wall with insulation

11mm OSB board (This one is optional but gives a much more substantial wall)

moisture barrier I find it is best to fit a breathable membrane such as Tyvek or Rubberoid, expensive though. If you fit the additional sheet of OSB the membrane needs to be firmly fixed with staples or the wind gets underneath it and it makes a hell of a rattle.

Batten using tiling battens, as this will provide an air space

external finish

Even though the plastic cladding is waterproof, I would still fit a moisture barrier

Hope this helps

Title: Re: UPVC Cladding
Post by Zambezi on Mar 10^th, 2009, 7:54am

Sounds good to me Woodsmith

Title: Re: UPVC Cladding
Post by simonsays on Mar 10^th, 2009, 7:50pm

Thanks for the advice woodsmith. I have now got some Tyvek. I am going to use foil backed plasterboard also.

Not going for the 11mm board, no room!

When using the Tyvek, how is it best to join the separate pieces of Tyvek, the stud wall is going up in three 2.5m sections.

Any other tips?

Thanks for all the help
Simon

Title: Re: UPVC Cladding
Post by woodsmith on Mar 10^th, 2009, 8:25pm

As long as it has a good overlap you should be OK.

Tips ........erm....use OSB ;D

The only thing I can think of is to use stainless fixings for the UPVC

Title: Re: UPVC Cladding
Post by simonsays on Mar 11^th, 2009, 12:16am

I will re-look to see if I can squeeze in the OSB board.

I presume I can use the Tyvek under my tiles?

Thanks again!