Low pitch roof problems

[JBR]

We have a bathroom and garage extension to our bungalow and, for some time, have been experiencing water leaks through the roof in some situations: heavy rain and wind in the wrong direction.

The roof to the extension is of a single slope ('lean to') type but of very low pitch (I'd say less than 15 degrees). To make matters worse, there is very little overlap of the slates. Both of these factors, I am sure, contribute to the water ingress.

Clearly the roof at present is inadequate and will need to be replaced. Does anyone have any suggestions as to the best remedy, please? One gentleman who visited suggested that the slates be replaced by a rubber compound mounted on timber (plywood?) boards.

 

[Mikefromlondon]

Hello JBR! you having a roof leak is not compatible, but do you mean felt type roof instead of slates? but you could felt your roof then place the slates back on as an option, are your slates made of rock material or synthetic slates?

 

[JBR]

Thanks Mike for your very quick response.
I'm not sure what you mean about our having a roof leak 'not being compatible', though. I do know that the pitch of the roof is far too low for standard slates, even if overlapped by the correct amount, and probably too low a pitch for specialised tiles.

The slates are natural slate and have felt underneath. I suspect that originally the felt probably accounted for capillary tracking of water under the slates which, as I said, do not overlap enough. However, something must have happened to the felt to allow water through, and I assume the same could happen again. I'm thinking that, if water is tracking under the slates, it would have caused the battens on the felt to have rotted and perhaps damaged the felt underneath. I'm no roofing expert, of course, but what else could have caused the problem?

The man who suggested the rubber covering meant that this would replace the slates, and should be supported by boards laid on top of the joists. He said that this rubber is a fairly new idea for roof covering. He did mention a brand name, but I can't remember what it was. Perhaps there's a better solution though?

 

[Mikefromlondon]

sorry JBR, I went away for a while, some temporary roof repairs can be carried out using a thick latex based or some other compound coating, applied with a brush like paint, or some other bitumen based thick coating to seal any small gaps, that dries up like a layer of rubber on top of the existing slates, as a temporary roof leak stop. This wouldn't be a permanent solution, and so you will at some stage have to remove slates to examine your underfelt, and renew along with any rotten wood.

B&Q do a 2L tins for a reasonable pricehttp://www.diy.com/departments/isoflex-liquid-rubber-black-roof-sealant-21l/35463_BQ.prd
Another one which is called rubba roof repair
http://www.rubbaroof.com/

There are many other types available, but some bitumen/tar based ones are not suitable for very hot temperatures where heat from direct sunlight in summer can cause them to run.

 

[JBR]

Wow, you're up late, Mike!
No, I want a permanent repair. The gentleman who had a look at the roof recommended rubber (or bitumen?) sheeting, rather than a paint-on rubber solution.
Anyway, whatever needs doing, I don't really feel up to it myself. Obviously, you're at the other end of the country, but I'm hoping that someone on this site could recommend a good roofer - in the south Manchester area - who could do whatever is necessary.
Thanks for your help.

 

[Mikefromlondon]

No worries man, best do it right and will last you another 20 or more years.

 

[JBR]

Thanks again Mike.

Can anyone recommend a roofer in the south Manchester area please?

 

[JBR]

Sorry to repeat myself, but can anyone recommend a roofer in south Manchester?

 

[JBR]

OK, I get the message!

 

[Mikefromlondon]

DIY. buy a scaffolding from Ebay and get up there yourself for a faultless workmanship.

Hey you should be able to do it yourself as that roof isn't high, plus the fact you will get total satisfaction that nothing has been bodged.

 

[JBR]

Thanks Mike, but I'm afraid I shall not have total satisfaction if I do it! Quite simply, I'm not knowledgeable enough to know what I'm doing, but thanks anyway.