Can anyone recommend either of these products for waterproofing an asbestos roof that has started allowing rainwater to bleed through?
There is Everbuild Water Seal from ToolSattion:
and "No Nonsense" Water Repellent Seal, Clear, from Screwfix:
I'm assuming either of these would be better than PVA solution - yes?
TIA
JD
see the other thread with the same question
Jim K
Pretty unusual for this to happen. More likely for water to be blown "uphill" by the recent windy weather. Black bitumous paint is the cheapest solution.
"harryagain" wrote in news:l9k7rt$j38$9@dont- email.me:
That was my first assumption too, - until I saw that droplets on the underside of the sheet were visible all the way back, for most of the length of the sheet. There is also some darkening of the sheet, especially along the troughs, suggesting it has absorbed rainwater. I gather now that such degradation of imperviousness is not uncommon as asbestos ages.
JD
In message , JakeD writes
You would usually get moss growing if the sheet is that porous; nice growing medium:-)
Check for fine cracks along the valley bottoms of the faulty sheets.
Could this possibly be localised condensation on the underside of cold roofing. Gas boiler exhaust nearby or some other local source of humidity?
I know you are trying to avoid changing the roof colour by replacement but you might be able to bodge from the underside. ISTR clear acrylic is available in the same profile. Could you remove the fixings and slide a sheet underneath. Or fit your old dirty sheet over the top of a new one?
Tim Lamb wrote in news: snipped-for-privacy@marfordfarm.demon.co.uk:
Thank for the suggestions. There is no sign of mould or moss on the undersides. I did wonder if it was condensation. However, there is no moisture forming on the underside of most of the sheets - only a couple of them. I guess they might be older sheets or from a pooorer quality batch.It lokks like not all the sheets came from the same source, because the profiles vary very slightly, and some look older than others. The sheeting is "big six" profile.
I could cover the whole roof in grp (at a a cost). But most of the roof is completely dry. Only a couple of the sheets have the moisture promlem and the moistire is drenching one of the roof rafters. The wetness is massively worse during heavy rain - which makes me thing it's leakage. Yes, it could be due to some hairline cracks. if it is, I hope that whatever I paint onto the top and underside will seal them.
JD
In message , JakeD writes
Moss will only grow on the top side.
You can get acrylic in big 6, not cheap though:-( Cement fibre roofing tends to flatten/spread with age so may not match well. Take care to avoid breathing any dust you create during preparation but note that asbestos health warnings are way over the top for roofing products.
Usually leaks will trickle down the underside until they drip off at an obstacle such as your rafters.
good luck
If it is of any use: I have the same sort of roof on the garage. A small section of a couple of the sheets are damp to the touch but do not drip water. The advised sealant is food for thought and is appreciated. It took me 5 years to find every pin prick on the roof. I used newspaper under the suspect areas, then a spot of silicone which sealed the drip.
I've only seen it come through cracks and screw holes myself. I have however, seen asbestos go to what one might call asbestos sand, and this makes it very difficult to clamber over without going through!
My guess is that this happens on faulty sheets, its dangerous as it makes it just give way. However I'm backing the blown water or through a hole issue. Brian
Tim Lamb wrote in news:nVRxOXu7OcvSFwP$@marfordfarm.demon.co.uk:
Good point. I don't think there is any topside either.
Yes - I think this is what may be going on.
JD
"Brian Gaff" wrote in news:l9krr3$da4$1@dont- email.me:
Yes. If painting the sheet with waterproofing solution doesn't cure it, I'll be paying close attention to the wind direction when I see that joist getting drenched in future.
JD
It all goes brittle. that's what the fragile roof signs are to indicate.
Once water has got under the roof, it will run down the underside of the corrugations.
I'd be inclined to make my own - dissolve a tube of silicone sealer in white spirit and paint it on.
Froby Ballgarrock wrote in news:l9n49f$6er$2 @dont-email.me:
Thank you for the suggestion! I had no idea that silicone sealant dissolves in white spirit, until today! Unfortunately, I've already ordered 5L of some waterproofing solution, but if it doesn't cut it, I may well try your suggestion. It's a method that I'm very glad to gnow about - thanks!
JD
Tim Lamb wrote in news: snipped-for-privacy@marfordfarm.demon.co.uk:
Tim, I climbed up onto the roof yesterday. There is no moss, exactly, but the older sheets (including the suspect one) had a fair bit of of lichen and some of blackish mould.
I waited till the roof was dry, then sprayed the entire roof with waterproofing solution (Everbuild Waterseal from Toolstation).
I then looked at the underside of the roof. I could see damp patches appearing on the underside of the sheet that I sepected was pourous. The solution was soaking right through. So, fingers crossed, the appliction of water-repellent solution will do the trick. If not, I'll try a second application, after perhaps scraping off the lichen.
Thanks again,
JD
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