Masonry Sill Repairs

[Matt101]

Hi everyone, I need some help with repairs to our exterior sills.

It is just a pretty standard terrace with what I assume are pretty standard sandstone sills and lintels which have been painted many times, and the sills have massive chucks missing from them.

Anyway my question is what mix would be best to repair them with? Another house in the street has had steel corner beading put around the edges of the sills to prevent damage of the bay and then a skim of render added over the top. Would this be a good idea?

Thanks for you help.

 

[Jon Maine]

Rendering a bad idea. Metal beads too.

Try to locate some stone dust from the same type of stone. Or find a chunk of stone and pulverise it. When you have finished doing that NHL 3.5 mixed with the stone dust 3 parts stone and 1 part lime should suffice. If the repairs are deep some stainless screws with stainless wire wound around to form a mechanical bond may help.

You will need to keep troweling back for a few days as it sets and shrinks to close the cracks. It may be good to dampen some
Hessian and cover it to keep it from drying out to quickly.

 

[Matt101]

Is there not an easier way to repair considering that colour match isn't important as it's going to be repainted with masonry gloss, it just needs to be smooth and have nice straight edges without chips missing out of them. Thanks again.

 

[17c_lancs]

Check out Lithomex:

http://www.stastier.co.uk/nhl/data/lithomex.htm