The original appearance restored for years to come without major structural intervention

A mid century house had inset reinforced concrete windowsills. One of them had shattered due to the metal reinforcement rusting and expanding. The owner wanted it restoring to look like the original and the others remaining on the front of the house.

The solution was to remove the rusty metal bar, knock back the remaining concrete to get it as flat as possible and then attach an L – shaped aluminium bracket to act as a support.

I then created a mould for the front face with a piece of upvc beading and infilled the base section with a strong 1:2 cement/sharp sand mix. After a little time the upvc could be removed and the front face smoothed. Then in a second stage more strong cement mix was built up to re-create the original shape, using wooden batons to compact and smooth off the outer surfaces.

Finally, a coat of masonry paint matching the other sills gave the finishing touch.

A rusted metal bar had to be removed and the remaining concrete chipped back as far as possible

An aluminium bracket was fitted and a temporary plastic retainer to hold the first layer of concrete

The base layer of concrete after the plastic retainer was removed

More concrete was added, building back the shape of the original sill

I used two lengths of wood to mould, compact and smooth off the final shape

A coat of masonry paint a couple days later after the concrete had dried to match the other sills

The front of the house showing the finished effect