I've got an outside window sill to repair. It has a couple of cracks that need to be filled. Do I just need to open them out and fill with cement? How would the surface then need to be prepared for painting?
Dave
If the cracks are big you need to rip-saw off and refix a new (reclaimed) sill length.
Otherwise, hack out well wide of the damage, fill with putty, after 2-3 days prime twice (doing any neccessary sanding down) the finish with u/coat (preferably twice) and top coat.
What is the sill made of, and what is the age of the house and construction of the walls?
If this is a concrete or brick (rendered or exposed) sill, then the crack is probably a point where movement will continue, so cement (or rather mortar) will just fail again. I used a non-setting filler from a gun which was suitable for overpainting, and squeezed it in the crack under high pressure. It's been OK for about 6 years since then. One which got left for many years without being filled resulted in a large chunk of the render coming off after water ingress and frost damage.
Sounds like it's a stone sill?
It's a concrete sill, 1890's house with brick walls. The sill currently has what I thought was a sheet of slate on the top, but must be something softer as pieces can easily be broken off. This is coming away from the sill and the cracks are underneath it. This will be removed and the cracks filled then painted. I see the point about movement, so the filler option is a good idea.
Dave
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