Windowsills dripping on wall - can I add a drip sill?

Discussion in 'Builders' Talk' started by Diz Manning, Sep 21, 2018.

  1. Diz Manning

    Diz Manning New Member

    Hello!
    I have a problem where the external windowsills on my house appear to be too short. When it rains, a wet patch appears under each window where the drips from the windowsill land on the wall. The house is stone and brick construction, c. 100 years old, and has standard concrete(?) windowsills. I've checked, and they do have a little grove under them to stop the drips tracking back towards the wall - so I think the problem is that they are too short, and the drips fall off the end and then land on the wall (they only stick out about 2 inches beyond the wall).
    Is there some kind of additional drip sill I can add under the windowsill - perhaps a piece of shaped metal to make the drips track slightly further out before dripping off the edge? Many thanks for your help!
     
  2. rogerk101

    rogerk101 Screwfix Select

    I had a similar problem with my concrete chimney caps. They also had the little groove underneath to prevent drip run-back, but some lichen had grown there and it turned out that the wetness was creeping back to the chimney by capillary action through the lichen. A good scrub with a stiff nylon brush sorted it out, and the chimney has remained dry ever since.
     
    Diz Manning likes this.
  3. HarDeBloodyHarHar

    HarDeBloodyHarHar Active Member

    Two inches should really be enough. Do you think maybe the sill is tilting backwards too much, enough to allow the water to pass the groove?
     
  4. Wayners

    Wayners Screwfix Select

    Not sure this is your problem but... My outlaws kept getting water and rot on the internal bedroom 2 window sill. I run new silicone around the external white upvc and replaced internal sill. Happened again within days so in an act of desperation, and before the rot set in I drilled under the external plastic sill at both ends and 300mm up the sides. Masked up the area so no chance foam would damage plastic and shot holes 50mm deep with a £5 tin of expanding foam. Allowed to dry and cut back foam then removed masking from plastic. Small amount of repointing and new silicone around the window frame and problem was fixed. That was 4 years ago.Simple enough to do. Foam sticks to wet better than dry surface hence it takes to skin so well. Don't get in on you!
     
  5. Diz Manning

    Diz Manning New Member

    Yes, I think it could be this. What should I do about it? Should I try to carve the groove deeper? Or could I slightly extend the dripping edge in front of the grove with some mastic or something? Thanks!
     

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