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Flat roof repair products

Discussion in 'Roofing and Guttering' started by Kaymo, 6 Jun 2019.

  1. Kaymo

    Kaymo

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    Location:
    Lanarkshire
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    Hi all,
    I've had a few previous posts about the flat roof on my extension and what to do with it, but for the short to medium term at least I am going to need to do some repairs. What I found the other day when I went up there is that water had got under some of the felt, and though it has not come through the next layer I and the next dry day I obviously need to get the water out and stick this edge back down. Although a lot of the rood is in good condition there are a few bubbles which I think it would be best to cut out these bubbles and patch, and then I was thinking to cover the whole thing with one of those roof seal compounds. I like the idea at least of these products and a continuous seal, rather than the joints in the felt where water can be seeping under as it has done in this case.

    There are obviously bitumen based products, and stuff like Thompsons High Performance Roof Seal and Isoflex Liquid Rubber, I have never used any of these before and was hoping anyone with experience can advise on products or their experience using them?

    Also, best products for sticking down the felt, and I presume any standard felt is fine for patching before putting on the roof seal?

    Thanks!

    2018-03-19 17.27.37.jpg
     
  2. bobasd

    bobasd

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    i'm afraid you've got problems with that roof - starting with the original design, and then how its been covered and detailed.
    the construction framing was poor - perhaps due to inadequate support framing when the Velux's were installed, and you've got pooling in the gutter. maybe a lack of adequate falls?

    cutting out and patching air/gas bubbles is not the modern best practice.
    where the felt join edges are lifting is no simple matter to solve - even if its even doable as a repair.
    theres no way that i know to "get the water out" - water vapour thats now in the roof will continue to bubble and lift any felt weak spots.
    painting the roof cover with some kind of sealer ight give relief for a bit but i doubt it for long term.

    a simple start would be to remove all debris from the roof and gutters, and check the soundness of the bay window roof felt.

    i know you've come on here for advice but you really need an experienced eye on site - there are RICS surveyors out there that claim to specialise in roof work.
     
    Last edited: 10 Jun 2019
  3. Kaymo

    Kaymo

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    Location:
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    Thanks bobasd. I recognise that there is a problem with the design, not just the lack of sufficient falls and detail. The design in fact is a can of worms because as I have discussed in other posts, if I am going to spend the money on re-roofing I would have liked to get it converted to a warm roof, but with the current design and sloping slate front that is impossible, which means a complete redesign and rebuild of the roof. Aside from building regulations, I am also in a conservation area, which means I can't even start with building control until I have gone through planning, and I can't start with planning until I have a new design and drawings.

    All of this would obviously take some time which is why I am where I am and thinking about patching and sealing. I am in the process of getting some roofers out also, to get opinions of best way forward and rough idea of cost for those options, but I doubt I will have everything in place, including funds, until another winter has passed!

    P.S. I have already cleared up all that rubble, its the only pic I had handy and was just after the stone masons had finished with the wall. The pooling in the drain channel in the pic is mostly due to the rubble, and it drains freely now that is clean, but the pooling to the left of the channel is permanent.
     
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