Cutting And Fitting Stone Windowsills in the Kitchen

We've gone all Blue Peter, as in, 'Here's one we prepared earlier'. For anyone who has ever cut stone windowsills in a house that is over three hundred years old; built by men whose plumb bob and lines were cock eyed after visiting the local pub, then you know where we are coming from. You think that a simple tape measure, a set square would be enough to get those forty-five degree angles but there is that cock eyed plumb bob again -- for those of you think Plumb Bob is the local drunk, you'd be very wrong, he was the seventeenth century builder -- the up shot is that nothing, nothing is straight in this house. Not even the garden is, it stretches wider as it goes up hill; it's all about the perspective! So, after being dumb, old and bold with a tape measure and set square and then swearing that the finished effect on the windowsill looked like a hankie for a hat we dug out some cardboard -- 'Here's one we prepared earlier' -- to make templates. The art of making a template is to cut it to the size of stone you are using, which is 300mm x 600mm and then place insitu. Here comes the craft part...

Use cardboard templates when cutting windowsills, saves costly mistakes.

You simply fold it in to position so it sits well, not snug, giving anything between 7-10mm space around the edge of the new piece of stone. Then cut to size with a pair of kitchen scissors. You need this 'wiggle room' for the mortar but also remember that stone houses are not level! This means there's good chance -- a bloody good chance -- that your windowsills over several windows, and we're doing four, are not level, they're not even in the same time zone. After making FOUR templates, all with differing angles we remember to mark the templates in that age old number technique of one to four; they're being four windows but you can knock yourself out, call them Tom, Dick, Harry and Delilah if you want, just remember which window is which or you will be singing, 'Why or why, Delilah' when you try to stick Tom in her (you see we could have been rude there but we restrained). Next comes the utterly scary bit, the angle grinder, wear steel toe cap boots, goggles, gloves, mask and anything else that will protect you. Cod piece springs to mind. Andrew has a beard and he says when cutting, even with the guard on, he can feel hot pieces hit his beard and singe it. Andrew has used angle grinders for years and still hates them. Angle grinders are scary and they can jump because no stone is ever pure, they have veins and hard bits in them, things that make your angle grinding disc jump in the night. Mark your windowsill off the template, we use a pencil and then cut along the line gently at first to get a groove and then allow the disc to cut deeper and deeper. If it jumps do not drop it! We did this once and skittered across the yard and buried itself in a sand bag, imagine if that was get the idea. 

How to cut stone with an angle grinder.

Cut the stone until it can be easily snapped or it drops off. We cut the stone on two wooden supports, and simply standing on the stone and the bit you want to lose can snap it. You can see in the photo above that the cut has been lined up with the wooden support, so it will be easier to snap. Don't be daft and think a tap of a hammer will take away the waste stone, it won't, it will shatter the stone. We cut all our stone on old wood because it lifts it off the ground, as you can see in the photo above, and means you don't cut your path or the tiles you've just laid, or the carpet, of the wooden flooring...oh, the mistakes that could easily happen when you are old, bold and daft.

Lay stone windowsills out dry before mortaring them in.

Next, lay the stone out, do not be tempted to start mortaring them in, best to lay them all dry at first to see if they fit but more importantly look balanced along the whole length. You will then need a very long spirit level. A steady eyed and nerves of steel.

How to mix mortar for bedding down stone for windowsills

We mix our mortar 3:1:1, that's 3 sand, 1 cement and 1 lime. We worked from one far window to another, from the highest point to the lowest. Best to do this or else you'll be taking the wall down to get everything level. Use the spirit level throughout, across the length you want them completely level, we do because a worktop will marry up to them. You will notice each windowsill has a tiny lip, a tiny piece that juts over the wall, this is not just an aesthetic thing, it is the exact width of our very long spirit level! We have a slight drop away from the window to stop condensation from sitting on the stone work. It shouldn't run off like a river but it shouldn't sit against the frame. We bed the stone on this mortar mix, be generous, better to gently knock the stone level with a rubber hammer or a real hammer with wood -- the wood is there to dull the impact, hit stone with a real metal hammer and you'll have real pieces of rockery to use in the garden -- any excess mortar can be scraped out from the sides and placed back in your mixing bucket.

How to mortar in stone windowsills

A completed stone windowsill

A dried stone windowsill for sealing

As you can see across the length we are level, the windows may not be but we cannot do anything about that, think Plumb Bob again. You then need to use the excess mortar to grout in the stone, filling any gaps. We use a pointing tool for this, a thin blade means we can get in the gaps but we also use a wallpaper scraper too and it does a good job. We have a damp rag ready to wipe away any excess on the window frames and a wet brush to keep the mortar wet, see our other adventures in pointing. The finished effect is great for us and we will seal them too to keep moisture, stains and mould out. This is yet another step in our journey towards a real kitchen. Oh, and the cost? For all materials, the total cost was £24.96 and it took two evenings, a total of 4-5 hours for the job.


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