Repairing a stone window cill

[Westholme]

I intend to replace an external door with a window in my 1894 semi. I have sufficient matching bricks taken from a chimney breast and internal wall to brick up part of the doorway. I want to avoid ending up with a square window at all costs and I think I can replicate exactly an upstairs window on the same wall that was originally a sash one. The doorway is in a cavity wall, with outer skin opening of 2' 6" and internal opening of 3'

I've been on the lookout for a free stone cill and I found one in a house where a window will be replaced by a door. There are a couple of issues, though:

1. The cill is broken. I helped remove it carefully today and it was very disappointing to discover a crack. The cill was intact for 100 years probably until some idiot drilled a hole and screwed a replacement plastic window frame into it. Each broken piece has half a screw hole.

2. The broken cill is 3' 6" wide and its window opening in a solid wall is 3'. As mentioned, my new window opening is 2' 6" on the outside and the extra width needed for the cill at either end is a half a brick, so I need a cill 3' 3" wide. Unfortunately the break is 1' from one end.

Can stone cills be repaired? And is it worth trying to repair and shorten this cill? It might be that it is shaped at both ends specifically for a 3' opening.

 

[88v8]

Arrgh. The best-laid plans...

It could be repaired by a stone mason with stainless dowels and epoxy.
Question is whether it would be cheaper to have them make a new cill.

Yes, surprising how easy it is to split stone or brick with the wrong size screw.

Ivor

 

[livias]

Depends how hands on you are, but I would do it myself
Stainless dowel can be substituted with a stainless screws
Car body filler

 

[Feltwell]

I've just had stonework repairs done, including crack repairs:-

http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=16614

All in-situ crack repairs are is the drilling of a hole at an angle across the crack, then inserting a length of stainless rod (stainless allthread - readily available on Ebay) with epoxy - easy enough to do - but.....

A cill takes no load, other than the window - so a joint in it is no problem if it's well supported. Put a bit of stainless dowel across the crack if you like, but I don't think it will do anything. The dowel is there to stop differential movement, so in a lintel to stop one side dropping relative to the other, but not a problem for a cill.

Which leaves you with an overlong cill with a crack in it. You can get colour matched mortar

https://www.lime-mortars.co.uk/stone-repair/repair-mortar

A crack repair can just look like a vein in the stone. Or you could shorten it by taking a piece out of the middle and fill that.

 

[Gothichome]

If you have to shorten I would shorten at the crack if possible. You can pound the removed bits into powder to mix with the epoxy to match the colour. Just a thought expanding on Feltwells idea.

 

[Westholme]

Thanks for all the replies. I collected the stone the day after my first post and here are a few photos taken today in 90 degree heat, if the forecast was correct.

http://oi63.tinypic.com/34g7wn7.jpg

http://oi65.tinypic.com/15gcg3p.jpg

http://oi64.tinypic.com/2wcl7vo.jpg

The stone was intended to extend 3" either side of a 36" window opening because it has a 3" wide level seating or stool at each end to support the brick jambs above. My house has a cill of the same size only about three feet away from the 30" wide doorway that will become a window. I also have cills with 30" openings but these have half-brick wide 4½" stools, although I have seen this smaller opening with 3" stools.

To be honest, I would not be at all happy cutting the stone if it were not broken, as that would be akin to vandalism. I plan to take Gothichome's advice and shorten it at the crack by 6" and adjust the existing brickwork to cater for 3" stools. The profiles of the cut sections probably won't match precisely, requiring some filling or filing.

An alternative option is to build up the stools inwards so they are 4½" wide and cut out only 3" but I am concerned about strength, durability and replicating successfully the two slopes next to the stools towards the front and the middle.

The broken stone is 11" deep and came out of a solid 9" wall. As this type of cill projects by 2", the back of it (albeit not perfectly smooth) was flush with the inside bricks. However, the shortened stone will go into a cavity wall and bridge the 2" gap between inner and outer leaves. In Building Construction, McKay says:

Projecting ends of stone or terra-cotta sills should be notched back from the inner leaf.

I'm not sure what that means exactly. The stone won't be deep enough to be flush with the inside of the inner leaf and I rather doubt my existing cill is 2" deeper because only one of the five external walls in my 1894 house has a cavity. I don't fancy removing plaster to see what is going on at this stage, therefore any guidance would be welcome.

As can been seen, I also saved the four sash weights. From the markings, I guess they weigh eight pounds each and they certainly feel heavier than one of my solid housebricks (~7 lb).

 

[88v8]

I think this is what my mother referred to as 'penny wise pound foolish'.
Fiddling around with the jambs to suit a cill that will now be too short.

Get it repaired by a mason, or have them cut you a new one the right length.

Yes, 8lb weights. There should have been makeweights as well, such that the weights in the top sash were heavier than the sash, so it stays up, and the weights for the lower sash were lighter than the sash so it stays down.
The shorthand for this is Pound over Pound under.

Ivor

 

[Westholme]

I think I've been 'pound wise' thus far: I saved a stone cill from being smashed to bits and spent £0 doing so.

 

[agbagb]

Stone cills have two main functions. 1. Direct water away from the timber of the window. 2. Keep the water off the brick underneath.

So for cheapo job, just cut and shunt at the break, 9" angle grinder for the easiest, or chisel one end to the width you need, mortar it in. Grind the top surface so it sheds water (coz it's lookin well pitted) then cut a drip groove underneath (4" grinder) so water falls off before it runs under and down the bricks.

Nice find for an easy, good looking, long lasting bodge.

 

[Westholme]

My broken cill probably has a groove along the bottom at the front.

The height of it is more than the existing cills in my house with 30" openings. What I have is 42" long x 11" deep x 4½" high with 3" wide stools and what I'd really like is 39" long x 11" (or 13") deep x 4" high with 4½" stools. Still, the cill was free and a new one won't be.

I went to the local reclamation yard yesterday and was rather disappointed with the selection of reclaimed cills. They had some but couldn't tell me whereabouts they were. They could make a new one at a cost of £200 inc. VAT (or £25 more if 13" deep). The price of the stone is their biggest cost at £120 + VAT per cubic foot.

Does anyone have a stone cill that is 3" high, so that it all fits in one brick course with full-height bricks resting on top? This would be for a smaller, non-sash window. If so, do you know the depth of the cill? Is it one brick + projection or only half a brick + projection?