Flat roofing options?

undaunted

Family member looking at flat roofing quotes, 3 roofs approx. 51 sq m in total, been offered a range of products & comments on pricing / what's "best"


GRP - I'm thinking likely to prove most durable, if possibly noisier


Rubber - Can't quite figure out why 1.5mm or so of rubber wont perish in the 20 years it's guaranteed for? More likely to tear if a tile from main roof falls onto it?


Felt - Cheapest in short term but least durable / more costly over respective lifespans


Olympic Thermaweld / Enviroflex liquid roofing / - Had never heard of either before but appear to be a waterproof coating, or torch on type product, each claimed by offerer to be far superior to grp. Appears to me to be probably no more durable than rubber / less than GRP?


Roof will have a metal (insulated) chimney flue out of one corner that products will have to be moulded / sealed around & (very) occasional foot traffic or ladder access (eg for cleaning guttering / access to upper flat roof) could be beneficial


Any comments on product pros & cons, particularly from experienced roofers appreciated

Grenage

Use EPDM, it's hard-wearing and allows more for movement than GRP - which will become brittle and fail.

cyclonebri1

Grenage wrote: »

Use EPDM, it's hard-wearing and allows more for movement than GRP - which will become brittle and fail.

It simply will not.

Glassfibre has been around for 50 years now, it does not fail or biodegrade, fit it and forget.

The earlier advice is disturbed to say the least

undaunted

Thanks for your comments so far. Whilst I can accept that rubber would probably have better expansion properties I must confess I find it difficult to believe that it will prove more durable than GRP - there are boats older than I am made out of the stuff & still out there going strong

Kiran

EPDM would be my suggestion too. Whilst I don't disagree with the comments over GRP it's installation has a lot to do with the workmanship of the installer. I have seen a number of fiberglass roofs where there has been excessive ponding and hair line cracking leading to water ingress.


EPDM is, depending on the size of the roof, available in a single sheet which removes the issue of poor coverage and cracking. Also providing your substrate is correct will avoid ponding.


If however maximum lifespan is your goal then a hot melt asphalt roof is tried and tested.

undaunted

By asphalt do you mean felt laid on bitumen from tar boiler - the "old fashioned" way rather than torch on felts that some use these days?


I may be being cynical but I'm increasingly inclined to believe that whatever method of covering is used the quality of workmanship is key to the job lasting / validity of any guarantee

Kiran

You are 100% correct regarding workmanship.


Regarding the hot melt roof it is a layer of a roof felt like material and then the asphalt layer over the top. It is old school but its the type of system that you only have the kit for if you know what you're doing and as a result tends to have less defects

Furts

cyclonebri1 wrote: »

It simply will not.

Glassfibre has been around for 50 years now, it does not fail or biodegrade, fit it and forget.

The earlier advice is disturbed to say the least

I will add to the wise mans comments!

Fibreglass roof vallies were available 30 years ago, and in common use with the volume house builders. A cheap and tough product that got thrown around on sites. These get a harder life than a flat roof because the roof angle means greater sun intensity, They also get frost- especially when moss is blocking them, plus the moss could cause damage - be it alkaline or acid, birds pooh and pollution.

These vallies are still going strong, so a properly constructed GRP roof could be the answer for OP.

Grenage

Looks like I'm eating humble pie here, then.

We had a place with a small GRP extension on the side years ago, and it was brittle as hell and had several cracks. I guess it was a duff job.