Replacing flat roof

[Vernon]

We have a large flat roof above garage/utility room. The roof slopes into the middle into a valley drain, with the recent rains we have noticed water is getting into the utility room. I cannot find the source of the leak, and have decided the best thing is to replace the roof altogether.

I have had a quote for a company using something called EPDM rubber membrane, not sure what this is, but having had a look around, there is also the option of fibreglass, or copy what is there and use felt.

I cannot find/decide what the pro/cons are for the various materials, any help would be much appreciated. I am sceptical of the guarantees that are offered, the EPDM had a 20 year warranty but is only single ply.

thanks

[<me9]

The most lasting options are to replace with either a pitched roof, or cover with more lasting[1] materials such as copper or lead.

Copper may produce a 'noisy' roof unless suitably lined first. Lead may need strenghtening work.

I would go for a tiled (or slated) roof if funds permit.

[1] Scrap metal prices being as they are ATM may not last!

[nightjar]

EPDM is a synthetic rubber, which is approved for use with potable water, which implies that it is unaffected by prolonged contact with water.

Provided the guarantee is backed by an insurance company, rather than just being offered by the installer, who may not be around in 20 years time, it should be credible. I quite like the look of the GRP systems though.

Colin Bignell

[freepo]

Friend of mine is going for the Fibre glass option, he says it's the dog's bollox.

[Vernon]

Thanks for the replies

I am trying to find a local roofer that uses fibreglass, but none I have called so far do it.

Are there any reputable national companies, that I could get a quote from?

FYI the quote for the EPDM roof was close to £2k, which does sound a lot, but if it lasts 20 years is not outrageous, still waiting for quotes for felt.

[Dave Plowman (News)]

I have a flat roof which is coming up to 20 years old - and it's just felt. Good quality stuff though I'd guess since an architect specified it.

[Ziggur]

unaffected by prolonged contact with water.

I have a friend who drives a submarine. He hopes (knows :) )that you are correct - his external hatch seals are EPDM.

[Ian_m]

When my garage leaked and certainly couldn't afford the priced quotes (that was straight replacement, fibre glass and rubber sheeting) I just replaced it myself.

As the original felt was hot pitch bonded (two layers) to roof it would have been imposible to remove did the following:

- Removed all the stones (+ cat poo + soiled nappy...yuk yuk) + moss + soil etc.

- Brushed surface thoroughly.

- Used some felt adhesive (or pitch filler, can't remember) to fill/glue any obvious problem.

- Used self adhesive underlay felt straight on top of existing felt. Stuck surprisingly well.

- Used slef adhesive felt on top of underlay.

- Touched up any "sub standard" bits with adhesive.

- I bought the felt adhesive in a 300ml sealent gun format, which I used most as very handy and easy to apply.

- The 500ml tub of adhesive I still have 18years later and only opened recently for kids playshed and is fine.

- Put stones back and survived for at least 15years until I sold the house.

The self adhesive felt was about 3 times the cost of plain felt, but youy don't have to mess around with painting/pasting the rather messy/sticky felt adhesive.

[Phil L]

I know a chap who installs the EPDM rubber system and has done for almost 20 years....his supplier issues the guarantees and he is obliged to do remedials - he has never been back to any of his jobs yet.

[dennis]

That is about how long a well done felt roof lasts. Keep an eye on it.

[Vernon]

I am certain that the roof is old, can't find paperwork, but when we moved in the previous owners left us a load of invoices for work etc. I remember the name of the company that did the roof, and they are coming next week to give me a quote, it will be interesting to see what the difference in price is (if any) compared to the "modern" alternatives. The owner (small local business) did say something about guaranteeing work for 20 years too, but it was a bad line, so I will wait to hear exactly what he has to say next week.

[Colin Wilson]

How fecking big is the roof ?

There are companies that will simply sell you the EPDM cut to size,=20 probably won't cost you more than a couple of hundred.

One of the sites in particular shows you how to install it from=20 scratch, including underlay, finishing the edges etc.

[claudia.towner]

A year or so ago I replaced my workshop roof with EPDM. I did it myself, and it's very easy. It's really just a case of laying a big sheet of EPDM over the roof, rolling it up to one end, putting down the adhesive, and rolling the sheet back into place. trim and finish the edges, and voila! It cost me a couple of hundred (for a 5m x 3m roof), and took just under a day. It looks very smart - much smarter than the felt roof on the adjoining garage.

dan.

[Vernon]

I may well have a go if the quotes are excessive, but it is not as easy to do, as it is effectively a V shape with a valley drain in the middle, with a couple of other pipes passing through the roof. I know that the roof above the garage is sturdy, T&G floorboards, but above the utility it is a little saggy, not sure what state that is in or what it is made of, so I expect it would have to be replaced after stripping off the old felt.

One other thing I have considered is fitting insulation above the roof, to try and reduce solar gain, as we are planning on using the utility as an office/playroom, I am not sure if this would be do-able but looking at the celotex website it gives basic instructions.

[Kevin Poole]

Would that be an architect like the one who explained to me that flat roofs should be completely flat because water cannot gather on a flat surface? And who, when a series of lakes formed, told me that this was good, because it ensured the roof stayed cool, which helped to preserve the felt? And who had specified Stramit boarding for it, which turned into something like a festering Weetabix when the inevitable leaks began?

Architects? I wouldn't let most of them design a pig-sty.

D-i-y advice, oft repeated on this group: if you want felt, do it yourself, and follow the Ruberoid Blue Book to the letter. Or why not d-i-y with EPDM? I'd be wary of a grp approach - how does it cope with thermal expansion, movement of the underlying structure, and long-term UV? Old Reliants suggest: not very well. If it does fail, how easy is it patch repair or remove and re-do?

[Dave Plowman (News)]

Perhaps - as with anyone you intend employing to do anything - it's best to check up on their work first.

I also tend to be a bit wary of these 'new' methods. Adverts always give the benefits but rarely mention any downsides. It may be they can work better on a badly designed 'flat' roof, but it would be time consuming to know truly how much if any they are better on a well designed one.

[Martyn Pollard]

You could DIY doing fibreglass. I have seen a job done by 'pros' and as long as you have all the parts, have prepped it and work quickly its easily DIY-able without any superhuman skills. The advantages I see include the fact you can easily seal around awkward shapes such as you mention. You can also patch it if needed and its good enough for boats.

If you take this route you could strip off the old roof and put your celotex in, then reboard with suitable ply. I think there a few websites which sell the resin and fibre matting, but please post back if you do go ahead as I'm going to do my garage roof with this method sometime.

Martyn

[dennis]

> Martyn