Need advice: How to fill this gap in our stone siding?

[Erik Loza]

We had our house leveled recently and this created some cracks and gaps in the limestone block siding. I can tuckpoint most of it but there are a couple of pretty substantial gaps along that opened up between this window and the jamb. Obviously, I want want to fill these but am a bit unsure about how to proceed. If I stuck some backer rod in there, it would just fall freely into the cavity between the siding and framing (original 1930's construction). There's not really anything inside that cavity for me to mortar against. Fill it with spray foam, then mortar over? Open to suggestions. Thanks,

Erik

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[Cameron Wood]

An additional piece of trim fastened to the window sill and contacting the stone would work, or an L shaped metal flashing.
I would avoid spray foam or any large amounts of caulking.

[Lee Schierer]

It the stone window sill isn't firmly attached to the rest of the stone, remove it and add a layer of mortar under it when you put it back in place such that it sits up where it was before the house was leveled. When you put it back, make sure the stone is sloped so water runs off the outside edge and the edge close to the window frame is higher. Stone sill should always be sloped away from the window.

[Tom M King]

I'm with Lee. I think whatever was holding up the inside of it has given up the fight, causing it to lose its slope, and it needs to be reset. It doesn't look like anything is sitting on top of the ends of the sill, so it should come up with some careful wedging. I'd use some low slope hardwood wedges with light taps in case any of the old mortar is still bonded to it.

[Erik Loza]

Thanks, gents. I should have included a more wide-angle photo. The sill is one solid limestone block, firmly mortared into place, and I would guess weighs at least 150lbs. Thanks also for advising against filling that void. I guess that was my underlying concern: The water will need a place to go. Removing the sill block without tearing the whole exterior wall apart and re-doing it is not really an option at this point. For now, I am leaning towards the idea of a metal sill with some PT lumber for support, with careful attention around the drain holes. Then caulk all that in place. Does this make sense?

Erik

[andy bessette]

I would simply fabricate a filler piece from the same material as the window frame; caulk and paint it to match.

[Bill Dufour]

Or tile over the window sill in a contrasting color.
Bill D

[Tom M King]

I would want to know that if it moved that much, will it keep moving. Can you shake it by rocking it? To figure weight, I'd use 100 pounds a cubic foot to get close.

What does the window apron under the window stool inside look like?

How old do you estimate this stonework is? I fixed much worse.

[Cameron Wood]

I would want to know that if it moved that much, will it keep moving. Can you shake it by rocking it? To figure weight, I'd use 100 pounds a cubic foot to get close.

What does the window apron under the window stool inside look like?

How old do you estimate this stonework is? I fixed much worse.

The OP already reported that the house was leveled, so presumably the wood frame with the window was raised, and the stone cladding stayed in place on the foundation.

[Tom M King]

Sorry I missed the part about the framing being jacked independently of the stone cladding. My only addition to the advice is that Lexel caulking works good for a painted transition to masonry. It bonds well to both materials and stays crystal clear. I've used it on very irregular meeting of old brickwork and painted trim. You can caulk the joint and paint a good straight line leaving some of the clear caulking right next to the masonry. This leaves a good sight line from not too far away.

The last time I remember such a caulking transition I've seen lately that has been done some years back was installed in 2015 and still looks good.

[Steve Demuth]

If it were mine, I would want the gap under the window filled with something permanent and stiff, before I dealt with the gap between the window base and sill at the outside. A mortar of vermiculite and fiber cement could be stuffed back into the whole to create a firm fill and backing. That's strong compressively, and water proof. I'd then fill with last 1/2" or so of the gap with an engineered plastic wood product cut down to fit, and "glued" in place with high quality silicone caulk behind and around it. Unless things move a lot, that will be reasonably flexible to accomodate seasonal movement, and will outlast the window itself.