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How to seal around old soil pipe on asbestos corrugated roof

Discussion in 'Roofing and Guttering' started by sparkwright, 27 Aug 2020.

  1. sparkwright

    sparkwright

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    What is the best way to seal around an old metal soil pipe which passes through a cement-asbestos corrugated roof?

    It appears cement was once used.

    Is cement the best way, or is there a suitable sealant which can be applied with a gun?

    Not looking for any drastic changes to the roof.

    Just want a relatively easy repair which will not crack and last a fairly long time.

    Appearance not very important.

    Cheers.
     
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  3. oldbutnotdead

    oldbutnotdead

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    Carefully, those sheets can be a bit fragile.
    Depends how big the gap between pipe & sheet is. If its only a few millimetres (up to 10 really) I'd be tempted to bodge a temporary seal from inside (gaffer tape would work) then build up a bead of black silicon round it from the outside.
    More than 10, Flashband probably.
     
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  4. sparkwright

    sparkwright

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    The pipe has a square plate round it on the INSIDE which is bolted through the roof.

    Rain runs over the top of this plate INSIDE.

    So I think I need to do the repair OUTSIDE, which isn't very hard to access as near the edge of the building.

    I was thinking of applying a sealant around the pipe.

    What is the VERY BEST sealant to use, which adheres to the asbestos-cement roof, and should last a long time??
     
  5. sparkwright

    sparkwright

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    Geocel Trade Roofers Mate seems to have very good reviews, does this sound like the stuff to use?
     
  6. datarebal

    datarebal

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    a lot of products will not adhere for long.
    You could try acrypol applied externally extend well past the immediate area up under the sheet above or flashing if there is one
     
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  8. catlad

    catlad

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    You can buy fibreglass matting tape for it if the gaps are larger than say 7mm
     
  9. sparkwright

    sparkwright

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    Ok, that's like plasterers scrim tape I imagine?
     
  10. oldbutnotdead

    oldbutnotdead

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    Nah, fibreglass tape like that isn't self adhesive, you need to apply it in combination with polyester resin. I think the resin will bond to your assie cement roof, it'll definitely bond to the metal. GRP is tricky over outside corners (eg the edge of a sheet of ply) but is fine on inside corners (eg your roof to the flue)
     
  11. catlad

    catlad

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    I can see scrim tape working actually!
     
  12. DIYnot Local

    DIYnot Local

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