Leaking single ply roof membrane

Discussion in 'Other Trades Talk' started by Simba_ali, Jan 14, 2020.

  1. Simba_ali

    Simba_ali Member

    Hello

    I have a balcony with wooden decking and a felt single ply membrane underneath...it's been fine for 2 years but last night we had very heavy rain which has created 2 large streaks of water damage on the bedroom plasterboard ceiling below.

    Any idea why this leak would suddenly happened and can heavy rain cause temporary pooling under the decking bad enough to cause such a leak?

    I now have 2 brown watermarks about 10cm wide and 2 meters long...almost like they are in the shape of a joist ?

    I've attached a picture of one of the marks

    Any clues?

    Cheers
     

    Attached Files:

  2. wiggy

    wiggy Well-Known Member

    To start with clear out any drainage channels
     
  3. KIAB

    KIAB Well-Known Member

    Could a join just weeping,but it could a leak far away & water is working it's way down, water can take some strange routes getting from A to B & usually not the most obvious route.

    Best option is to replace it with a GRP deck, has no seams to leak.
     
  4. Simba_ali

    Simba_ali Member

    Drainage channels are all under the decking so I managed to lift one plank and clear away any debris from the main drainage pipe going down. There wasn't much to be honest.

    Would it be advisable to lift the decking near the leak sites and see if any debris are restricting the draining off of water? The planks are a pain to get up is the problem....
     
  5. wiggy

    wiggy Well-Known Member

    Its going to have to come up at some point.
     
  6. Hans_25

    Hans_25 Well-Known Member

    As it was likely windy too, could be rain being driven into the side of the structure and making its way in there? Either way you really want to get to the bottom of what's going on and remedy it, water in the structure will cause no end of issues and a lot more cost if not rectified.
     
  7. KIAB

    KIAB Well-Known Member

    Will rot out joists, etc,eventually.
     
  8. Simba_ali

    Simba_ali Member

    Hello

    So a small update, I managed to do some measurements and established from the attached photo that the line coming off the main water mark is where the patio door is on the balcony above.

    I packed under the door sill with plastic sheeting and last night the leak was much reduced after more heavy rain(one patch)

    Is it likely the roof is not the cause, but the water is getting in under the bottom sill of the doors?

    I find it strange the leak suddenly happened in the roofing membrane which is covered by decking.
     

    Attached Files:

    Last edited: Jan 15, 2020

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