Board logo

Educate me about flat-ish roof coverings
DIY Si - 28/7/15 at 05:46 PM

Evening all. I've not long completed on a Victorian red brick cottage that is need of some work. One of the things I will be doing is making the old tiny kitchen, rear lobby and brick built outbuilding/outhouse into one open plan kitchen diner. As such, the current flat roof over the lobby and bathroom is going to be replaced. Partly becuase it's old and partly because the lobby is covered by old poly-carb type panels and the ivy has come inside. The new roof is going to be about 2.5m x 3.5m, ish.

Once the roof is off, what options are available for replacements? I'd rather not have the old board and felt roof back on, and what ever is it needs to be readily accepting of roof lights. I'd like something different, and I know that usually means more money, but I have no idea how much something like a sedum (sp?) roof covering would be to install. Likewise, I wouldn't object to either a copper or zinc roof, a la Grand Designs, but I'm aware these are likely to be many shiny pennies!!

So what options are there? What am I overlooking, or know nothing about?


twybrow - 28/7/15 at 05:55 PM

I would be looking at a fibreglass roof. You cab DIY or get a pro in. They are very robust and would far outlive a felt equivalent for similar money. If done well, you can expect 30 years useful life....


JacksAvon - 28/7/15 at 06:36 PM

PDM roofing?

It is a rubberised sheet, looks to be very good


daviep - 28/7/15 at 06:56 PM

As above EPDM is reasonably easy to DIY. I've got it on a flat roof and was a bit nervous about doing cut outs for extractor fan exhausts but turned out to be very simple.

Cheers
Davie


Rosco86 - 28/7/15 at 07:55 PM

GRP all day long, can be made to look like lead by using the simulated mouldings, easy to diy and for the materials is probably cheaper than felt


tegwin - 28/7/15 at 09:17 PM

I would be laying thick foam and then OBD board and finally covering with EPDM.

I re did my garage roof with EPDM 5 years ago and it still looks as good as it did when I installed it. Even with the local kids playing on it occasionally its holding up well. The edge fittings to seal it and finish it cosmetically look really nice and it was low mess and easy to fit.


Very highly recommended from me for value for money and finish. Definitely investigate "hot roofing decks"


van cleef - 28/7/15 at 09:33 PM

I used to be a roofer

I used to fit Firestone EPDM which a reasonably good product, with a 20 year guarantee with an installation by a trained fitter.

If money isn't an issue I would go with sarnifil which in my eyes is the best product out there which can come with lead like rolls and folds to look similar to lead. Rhepnol is a similar product to sarnifil but is a lot cheaper.

I personally find GRP quite crap....which I've seen separating from the timber deck quite a few times and going brittle after time, which isn't good if your wanting access across it.


cliftyhanger - 28/7/15 at 09:35 PM

Did my garage 2 years ago with GRP.
I had help, but in a 12 hr day we fitted all the OSB (3) boards, fitted the premade GRP trims and did teh actual GRP. That was a 30m roof, never done GRP like that before. Total cost then was £600 plus the OSB.
At the time I had quotes on a trade basis of £1200 to felt the roof, the guy reckoned materials would be £600. (bear in mind this is Brighton prices, so expensive with the rest of the UK except London)
The GRP is tough, and appears to be durable. You will not get it as smooth as the pictures show, I understand they sand the GRP down for those before the topcoat. However, if you want a fine finish, you could use a coat of coarse matting, and a fine one on top.


DIY Si - 29/7/15 at 08:06 AM

I'm not sure why, but I don't like the sound of the GRP covering, as I might need access to the top of the roof from time to time and I'd worry about it cracking.

The EDPM sheets sound like a much more practical version though, especially if there's versions that look like lead, as that would suit the age of the house very well. Thanks all, I shall go and get my Google on!


twybrow - 29/7/15 at 03:58 PM

Why would you worry about grp cracking if you walk on it? Think of a large grp yacht, the loads and uv exposure on that in rough seas will be far higher than you walking on a roof, and the grp would last 30-50 years if it was well made to start with. But each to their own!


DIY Si - 29/7/15 at 05:17 PM

I suspect it's more to do with my ability to get it right first time more than anything!!