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Flat roof material choice

Discussion in 'off topic' started by Whaleblue, Aug 27, 2019.

  1. PaulMB

    PaulMB pfm Member

    I had no idea! On "The Continent" one tends to think of the UK as very tranquil, safe, law-abiding. Gently paternal Policemen armed only with a whistle.
  2. Whaleblue

    Whaleblue Southbound

    Builder (who is highly recommended on the Which? Tradesmen thing), and is clearly brighter than average is very much preferring GRP, and assures me that if fitted correctly with required expansion joints will be the best option. He suggested that only a poor construction approach would lead to issues.

    However, he’s agreed to look into EPDM. His concern is that while it may work on simple flat roofs, he’s encountered issues where it has been used in more complex fits - such as integrating with something like a Mansard.
    Rockmeister likes this.
  3. hifinutt

    hifinutt hifinutt

    come and see the floppy unattached fragile epdm roof next to mine

    Three most common problems with Rubber Roofs is improper installation, shrinkage and the seams. While the rubber roofs are known to be durable, they also need maintained. EPDM roofs are fully adhered or as many call it glued down. The system is not attached mechanically.

    One of the biggest reasons a rubber roof can fail is from improper installation. If you are set on a rubber roof, make sure the roofing contractor is fully trained and experienced in installing a rubber roof. This product is a roll and therefore roofs with parapet walls the EPDM rubber is installed up the wall also so that when it rains water is not trailing down in-between the rubber and the wall. We have seen some roofs that have just been cut and glued to a spot and this is not correctly accomplished. The point of the roofing material is to seal the roof so that water cannot travel to the decking and interior of the building. Not correctly attaching rubber to corners, walls, around drains, pipes and other areas will assist water to finding an area to get into.

    With EPDM rubber roofs being glued down roofs, the roof must be maintained because seams will need adjusting, as they can start to pull apart. Even if properly installed after so long the seams will need serviced and the roof should be inspected regularly to make sure the roof is performing the way it should.

    The other common problem is the shrinkage. After so long the rubber will begin to shrink causing it to pull away from parapet walls, flashings and other areas that once again leaves room for a leak to find its way to the decking. This is another reason the roof should be inspected at least annually and this is what should be looked for. Sometimes this does not seem like a lot of shrinkage but on a big roof this can be a lot.

  4. Rockmeister

    Rockmeister pfm Member

    we built a 'rubber' roof in the previous house and it's fine on a simple flat plane, but need VERY good instalation ( a lot of cutting and folding) on complex shapes and those joints are prone to be the first to go. We inhereted a fiberglass pitch on this house. It was built in 2005 and is just fine. I've never heard a creak in its life, its totally watertight and since it is also insulated, is quiet and warm. Also, easily strong enough to walk around on for maintenance tasks. They come in colours (ish) so think carefully...ours is light grey and a tad 'sore thumb' on our red stone lodge house with its graded welsh slate elsewhere. Dark grey is the way to go.
    One other thing. Ours faces NW and doesn't get much sun and is therefore prone to Algae build up after a wet winter. Thats fine because it's easy to clean but unlike real tiles, it does show up, so you'll need to be up there once a year if you are similarly positioned.
  5. Whaleblue

    Whaleblue Southbound

    Thanks chaps. As my builder is clearly comfortable with GRP, and assures me it will be creak free, I strongly suspect that’s what we’ll go with.

    Useful discussion, thanks.
    djftw likes this.
  6. Colin Barron

    Colin Barron pfm Member

    If you decide on rubber pick a roofer who has been around for generations and give a good warranty. I think you can get 20 or 25 years manufacturers warranty.
  7. djftw

    djftw Heterodox Member

    I am late to the party, but just to pile in anyway... *If constructed properly* GRP roofs are superior, my former employer used to offer a 99 year warranty on them vs 30 when they used to offer EPDM. We did once come across a competitor apparently offering 50 year warranty on EPDM, but their small print revealed this was only where a single piece of membrane was used with no joints. EDPM might be a very sensible lower cost option to replace old felt and tar on a dorma window or similar small area on an existing structure. But for a new roof with a competent designer and installer I'd go GRP every time.
  8. cctaylor

    cctaylor pfm Member

    We were very happy with GRP replacement for a failing traditional felt roof on an extension, this faced south and we weren't aware of any creaking. Roof was 4m X 12m.
  9. Whaleblue

    Whaleblue Southbound

    Thanks both - helps confirm GRP is the way to go.

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