Choice of breathable membrane for an outside building

[DavidE]

Hi there,

I've just started making an outside store building for some horticultural equipment. The main criteria is it keeps dry (really good insulation is not a concern). The initial construction will be a brick plinth with 4 x 2" studding on. I have just been revisiting some of the posts I've read here before and seen the good advice about having a gap between the vapour barrier and the cladding. The cladding will probably be some sort of feather edge board - maybe Larch if I can find a local supplier.

My question concerns the breathable layer. I will be getting some stuff from Screwfix soon as I have a 10% voucher off for the Trade counters. I wondered if I could be opportunistic and get the breathable membrane from there if they were competitive...
http://www.screwfix.com/cats/101893/Building/Roofing-Insulation

Looking through the products the only two they have for frames are both insulated as well (which I could be tempted to use). However, I was looking at the roofing underlays and wondering what would stop me using those eg the Protect A1 or the VP400.

I'm quite happy to get it from another supplier if the Screwfix stuff isn't suitable - I'm a best just looking for a Tyvek brand layer - or is there a good option from Screwfix?

Thanks, David

 

[MikeG.]

David,

an un-heated, un-insulated and un-occupied building wont need a vapour barrier at all.

It sounds like you are doing a decent construction..............if there is any chance that you might occupy the building later then by all means include a vapour barrier, but as a garden shed you really don't need one. If you really want to use something, you could put a building paper behind your finish (boards or whatever), but you should then space the boards or render off the paper by using battens.

Tyvek Housewrap (or is it Homewrap??) is the standard stuff.........and costs a fortune! Complete waste of your money here!!!

Mike

 

[DavidE]

Hi Mike,

Thanks for your reply - an interesting point! My logic for the inclusion of a barrier stems from an existing shed. It has shiplap construction which has moved/stroke lost the odd knotty bit. Therefore you can see a little daylight through it. When you get driving rain a bit of water can get through. (I do appreciate a good solution is to reposition the boards to close the tongues up! ) Therefore, I figured a barrier behind the new building it would help with overall integrity of the building. I can easily be talked into saving money though!

Thanks again
David

 

[MikeG.]

Well David....the building paper is your answer then.............it'll save you a fortune ove the Tyvek.

Mike

 

[DavidE]

Hi Mike - okay brill I shall procure a roll when the time comes to clad.

Cheers
David