Lead Gulley Repair

Discussion in 'Builders' Talk' started by ProfSnail, Sep 19, 2021.

  1. ProfSnail

    ProfSnail New Member

    I am soon going to attempt to repair a south facing lead lined roof gulley. The mortar has all cracked and become detached from the lead and also from the tiles.

    I don't see how mortar can ever successfully seal to a lead sheet, particularly when the lead to subject strong sunshine and thus differential expansion. I propose to remove the existing mortar and stick a bird deterrent "Prickle Strip" onto the lead gulley, underneath where the mortar will go, and then apply mortar above it in the usual way. The idea is that the spikes on the "Prickle Strip" will ensure that the mortar does not become detached from the lead sheet over time.

    Do people think that this will work ?
  2. Wayners

    Wayners Screwfix Select

    Ones around me were replaced with fibreglass gully..

    Not my area but bump your post up
  3. ProfSnail

    ProfSnail New Member

    This is a picture of the "Prickle Strip" glued in place. I have now applied the mortar over the top, and we will see how it works over the years to come.

    Attached Files:

  4. GRH

    GRH Member

    It does seem counter-intuitive doesn't it, but if you have ever cleaned a cement mixer a day or two later, you will know cement seems to stick to everything with a passion. If you look at lead-work on say, a chimney, you will see it has no problem keeping it in place.
  5. Abrickie

    Abrickie Screwfix Select

    Can mortar on a flashing truly be compared to that on a valley ? With a flashing it’s at the point where the lead is fixed in place whereas in a valley it’s not.
    The mortar in a lead valley should be on undercloak board ( cement board) which sits on but is not fixed to the lead ;)
  6. GRH

    GRH Member

    I bow to your greater knowledge sir, and have filed that away for future use.
  7. JOMEL

    JOMEL Active Member

    Hi Guys

    Well that takes me back some
    I used to make a fix valley gutters of all kinds in lead.
    But they would lie in a timber gully fitted by the joiner.
    And then be turned in then the tiler finish over it.
    Compo never entered in to it from what I remember.
    Is it an old building.
    I repaired an early 1800 valley gutters on a building in Newcastle.
    It seemed rather special.
    I cant get a hold of the pic have you got another.

    Johnny M
  8. ProfSnail

    ProfSnail New Member

    Thanks for your reply, that explain to me how it was supposed to be in the first place.

    In my case the undercloak board appears to be too far underneath the tiles for the mortar to all sit on top of it. It looks like it has previously been repaired with mortar partly onto the side of the lead gulley and partly onto the undercloak boards. I guess this is why the sunshine has cracked the mortar off the lead. I am hoping that by sticking the Prickle Strips to the lead and then mortar on top of that it will last.
  9. ProfSnail

    ProfSnail New Member

    Thanks for your reply Johnny. I think, in retrospect, that the title of my thread is a little misleading. I have repaired the mortar at the side of a lead gully, between the lead gully and the roof tiles. The lead which makes up the gully is in good condition. The building is from the 1990's.

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