Windowsill Restoration

[L_Bow]

Hi everyone,

I have a damp patch under a windowsill in my Victorian end-terrace. Looking outside I can see some gaps in the pebbledash beneath the sill which may explain part of the problem. But I've also noticed that what I had assumed to be a painted solid stone sill actually has some kind of soft white material built up on top, a visible hole on the top surface, and from peering into the gaps, appears to have a lot of empty space inside. There's no sign of a drip edge on the lower surface of the sill. I'm now questioning how the sill is constructed, what a windowsill even is normally, and whether I should consider a more complete restoration of the sill before re-rendering the wall and sealing gaps. Could the white material be there to add a slope for water? Or repair gaps and cracks? What kind of trade would I need to contact to get an old windowsill correctly deflecting water? The sandy dust is from old pebbledash - please ignore!

Many thanks for your input,
Lewis

 

[Cubist]

I think what you have there is an old stone window cill that has suffered some damage and erosion in its life and at some time a new UPVC window frame has been installed. The surface of the stone cill may have been repaired with a mortar of some kind before the final closure seam between the foot of the window frame and the new top of the cill was filled with a caulk of some kind. Any general builder should be able to make all the necessary repairs for you and these should require minimal materials and work.

You could in the meantime make a temporary repair to prevent further water ingress by pushing some PlumbersMate putty into the gaps and holes or use a silicon sealant.