What would everyone recommend to repair a cracked Masonry Windowsill?
I’m seeing various caulks/synthetic fillers but want it done the proper way.
Thanks
We have a number of cracked cills on the rear elevation of this 1879 stone house. The cills are Doulting Oolitic Limestone and they have failed in the middle because the ends have settled very slightly under the weight of the house whilst the wall under the centres of the cill has stayed put, unaffected by settlement. On this three storey house only the cills at basement and ground floor level are thus affected. Eyeing along the cill will confirm this diagnosis. For this reason there should be a void under the middle of such a cill, and the mortar joint should only be shallow pointed with a softish lime mortar. On the cill that I have repaired I raked out the crack and filled it with a plastic stone repair mix. These can be bought, but mine is 1:3 NHL:Aggregate, where the aggregate is 50% ginger sand, and 50% Doulting stone dust. The crack should be well wetted before filling, and the repair needs to be kept damp for a few days so that it sets properly. Such settlement is likely to have occurred when the house was first built as the lime mortar set up to full strength over several months, in which case the repair should be pretty much invisible and last well as mine has. Hope this helps.
