Repairing Bay Window Masonry Surrounds

18 Feb 2015
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United Kingdom
I’d like to repair and decorate the exterior window masonry surrounds on the front of my Victorian terrace. As far as the pillars, decorative mouldings and lintels go, I think it’s a fairly straightforward task of burning back the (many layer of) old paint, sanding and re-painting. I’ve had some local decorators quote on this.

However, my main window sill is in really poor condition and badly out of shape. Could a decorator reshape this with some sort of exterior filler or do I need to get a builder or stonemason in to reshape / rebuild the sill?

And how is the work best carried out?

Here are some images of the current condition of my masonry surrounds:

And here’s some images of a neighbouring house that I’d like to achieve a similar finish to:

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Use an epoxy mortar product. Getting a good key is important. You may need a temporary timber support for areas under cills. Your decorator could probably do this of he understands what he needs to do.
Ooops sorry, i did try searching for that but couldn't find it, will have a re-read.

However my question now relates more specifically to the reshaping and rebuilding of that particular window sill and the process of doing this.

I've had a few (dulux certified) decorators round who were comfortable with burning back the old paint on the stonework, sanding, preparing and re-painting. But less happy to take on the sill repair... is this more a builders job?

And what is meant by 'getting a good key'?

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Repairing the sill is fairly easy but it's a mistake to try and make it look too sharp and clean. This is 100 year old stonework and shouldn't look like a Barrett house. For the record I think your neighbours sill look terrible. Just follow Bobby's previous advice and use a renovation repair mortar. You just want it to look reasonable but not too perfect.
"keying" means having a rough surface free from dust old paint etc. that new mortar will adhere to. Looking at your sill, it looks as though it has a brick core which is rendered (covered in mortar) and smoothed of. I had this on outside gate pillars, and the mortar cracks, water gets in and when freezing, breaks of some of the mortar showing the brickwork. In your case the brickwork has been painted along with everything else. So chip of the top surface of the whole damaged area to expose what ever is under the paint.
"keying" means having a rough surface free from dust old paint etc. that new mortar will adhere to.

I had one quote from a chap who said he'd only take off the old paint on the decorative mouldings. He suggested the stone pillars could be filled, smoothed and repainted over without taking the old paint off first.

Bad advice i suspect?
I would chip off the white paint on and around the damaged area, then make good. if you put a piece of wood with a bit of plastic sheet on it (stops the repair goo sticking) horizontaly under the edge then you you can fill down to it and use the existing surfaces to match the levels.
When your repair has cured, then rub the whole pillar down with fairly coarse aluminium oxide paper, paying particular attention to the grooves where the bands meet. This will sharpen up the effect of them. Give it a good wash down then proceed to paint it. Its a hundred years old, that window of your neighbour's looks like its made from UPVC.

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