Window sill sealant?

17 Jan 2012
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Tyne and Wear
United Kingdom

I'm looking to replace an old window sill (and by 'replace' I mean fit a pvc window sill on top of the original wooden window sill as it can't be removed as the wood seems to be fitted into the surrounding walls).

As my walls are out, especially on one side, I'm guessing that there will be gaps in places between the new sill and where it meets the wall. Is there a certain type of sealant that should be used to fill in these gaps?

Can I just use decorator's caulk (though I'm wondering if it will adhere to pvc?) or silicone sealant, or something else.

Thank you.
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I assume you mean you are fitting an internal window board?
A bead of silicon will be as good as anything, Dow Corning 781 is what I would use.
It's an internal window sill, but not wooden - pvc.

Thank you for the suggestion.
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Removing the old window board is easy, chop out a 2" section in the centre of the window board from the front to the back then knock the left and right hand sections inwards, use these as templates to cut the horns on your new wooden window board

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