Advice needed about wooden external window sill.

[Commandpod]

Hi, I need to replace an external window sill under a square bay. The original has rotted away in parts. The original top section is under the double glazed window but the hardwood I have is too deep to do this as is.

I feel I've got 2 options: plane it down (could be difficult) or make a rebate so that an inch goes under the double glazed unit and the rest abuts the window on the outside and is then sealed with silicone. The rest of the gap under the window frame could be filled with door grade foam.

I am veering towards reducing the depth of the whole piece rather than rebate because of expansion issues but wondered what you thought? What would be the best way of reducing the depth? It would be 4 inches in width, about 1.5 metres long and I need to lose about 1/4 of an inch of depth.

 

[Bingy man]

Welcome to ukw - a few picks of the window and rotten parts will help members give you the best advice. As for reducing that hardwood then a tablesaw , bandsaw or planer thicknesser would be you best bet . You don’t say what depth this timber is but you could possibly do it with a circular saw ( a mains one )

 

[johnnyb]

Rebating is a bad idea as it would give the water a collection point(silicone is a bad idea being unpaintable as well) slope off to allow drain off.