Is anyone here able to advise on which is the best breathable roofing membrane to use (from a condensation-preventing point of view)? The choice was originally between Klober or Tyvek, now we have been told that there is a more expensive product called Roofshield which has a higher specification.
This information is for a friend of mine who has to decide pretty quickly which one to have fitted, so any comments from someone who has used any of these would be greatly appreciated.
With out a shadow of doubt. from 50 years plus in the slating & tiling trade, ROOFSHIELD about £108 inc vat
Thanks Keith, that's confirmed what we were thinking - and the one he'll go for.
By the way, he's paying another £8500 for the roof to come off and this breathable membrane fitted - this includes new lead gullies and new tiles for the back of the roof (the better old ones were re-fitted there last time).
A bit of a disaster for him, so let's hope this sorts out his problem.
Many thanks for all your help.
Giles.
The only down fall is the Lead valleys or gullies. Lead should be code 4 or
5, preferable 5, laid in lengths no longer than 1.5 mtrs, fixed with two rows of copper nails 50mm apart across the head only. With a 100mm wide fibre cement strip laid length ways either side of the lead with the outer edge of the lead turned over the strip. The strip should be held in place with a continuous line of Leadmate. NOT NAILED. The fibre cement strip is for bedding the mortar on to, as lead expands and contact cement mortar will suck water between the lead and mortar, like two sheets of glass. In my opinion GRP valley section are far better. They are purposely made for concrete tiles. Others my disagree. I would love to have been able to do the job, but I live in Nottingham and the travelling costing would be to much.
That's ok, Keith, I do understand that you're a bit far away. I have forwarded on your advice above about fitting the lead valley. When he had the new roof fitted, with the cheap non-breathable membrane, the roofer did fit those GRP valleys and my friend definitely wants them replacing with lead.
He now has a real bee in his bonnet about it because he says that the condensation is particularly bad around the GRP valleys. He tells me that the new roofer is going to fit code 4 lead. None of this means much to me, but he seems to have researched every aspect of preventing condensation in his roof (understandable I suppose!) and is determined to have the job done as he wants it.
He has told the roofer that he wants Roofshield membrane, as you recommended.
Thanks again.
Giles
He now tells me that, after I forwarded what you said, he has changed his mind and is going for the GRP valleys. Apparently the original roofer fitted a cheap type - as he did with everything else! - but he is having them replaced with Redland GRP valleys.
"Cut
Giles, in one of your reports you said that the reason for lead was the amount of condensation was mostly in the valley area , with GRP valley sections. The reason for this is that the condensation would run to the lowest point from the inner roof.
There must be a length of underlay membrane full width laid from top to bottom under the GRP valley section and the horizontal underlay lapped over this forming a double layer.
Keep in touch on the progress Keith
I'll pass that on Keith.
I will keep you informed, many thanks.
Giles.
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