Caulk under window sill

Hi guys

The window sill on my bay window is a little drafty, see pic - theres a small little gap in the side and underneath the window sill.

How best should I fix this?
Caulk? If so what type of caulk do I use?


  • Reddleman79Reddleman79 Forumite
    58 Posts
    Second Anniversary 10 Posts Name Dropper
    I'd use decorators caulk as it's slightly flexible and can be overpainted. Silicone won't take paint.
  • flashg67flashg67 Forumite
    3.8K Posts
    Part of the Furniture 1,000 Posts Name Dropper Photogenic
    Is there a corresponding gap outside that might need sealing too? This would need a silicone or  frame sealant
  • housebuyer143housebuyer143 Forumite
    1.6K Posts
    1,000 Posts First Anniversary Name Dropper
    Get some cheap caulking from Screwfix for about £1. It's fantastic and can be used for so many things. Worth having one in the house at all times.
    Filled so many drafts recently with the stuff.
  • edited 23 December 2022 at 9:04AM
    ThisIsWeirdThisIsWeird Forumite
    1.1K Posts
    1,000 Posts Name Dropper
    edited 23 December 2022 at 9:04AM
    That should do the job nicely.

    Bear in mind, tho', that caulk is not sandable like normal filler, so would need smoothing off properly for a good finish straight off. It is water - based, tho', so can be smoothed well using a wet filling knife, finger or similar, or excess wiped off with a damp cloth. But any caulk you don't want will be awkward to remove after it's dried, and can't just be successfully sanded smooth, so get the finish you want when you apply it!

    Tbh, for the areas you've shown, you should get good results blending it in with a wetted finger, following the profile of the cill-to-wall edge. Squish a good bit in, to at least an inch's depth. Smooth off with wet finger. Use damp cloth to remove any unwanted excess spread over surrounding areas. It 'skins' pretty quickly, so get the required finish/excess tidied up without too much delay.

    The draught isn't necessarily coming from an outside gap in the frame, but could be from the wall cavity.

  • greenface2greenface2 Forumite
    455 Posts
    100 Posts Second Anniversary Name Dropper
    is the picture inside or outside ? caulk inside and a bit of sand and cement outside it it will squeeze in .
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