Filling large holes from old sash hardware

[Georgeonthecrescent]

I am renovating a large Georgian sash window in my kitchen (re-puttying, replacing some glass panes, re-weighting, sanding, filling, painting etc.). For small holes I have been using Ronseal High Performance 2 part filler. But I’m unsure what I should use for these very large holes where fasteners have been added and removed over time.

I’m aware of specialist epoxy resins like RepairCare and Timberbuild. Ideally I would use a liquid resin to fill the holed, and then a putty to reform the missing edge. But buying something like RepairCare just for this feels like overkill. It’s very expensive!

What would you recommend?


(The new hole on the top left was where I had to drill out a very stubborn screw and the bit slipped )

 

[mardinor]

If that's where the fasteners go, and therefore the repair will be inside, then you're fine with the Ronseal. Repaircare/Timbabuild is only really needed externally, and especially where water gathers.
To rebuild the edge, I'd tape a plastic ruler against it (smothered lightly with vaseline or wax polish as a mould release) and push the filler against that. Makes sanding much easier. And build it up in 2-3 goes, which is easy as it hardens in 10 mins.

If I'm misunderstanding the location and it's external, you might just get away with Repaircare fine surface filler (which is one part and needs no primer, so much cheaper). That can do up top 6mm from memory, so could cover in a few fills.

Oh, and well done for renovating the windows. You literally cannot buy wood as good as that.

 

[a twig]

If it isn’t going to be visible you could just fill it with a 2 part epoxy. I’ve used the gorilla branded syringe one for jobs like this in the past, it dries clear and can be drilled / sanded - not cheap on a per litre basis but as it comes in a small amount it’s great for the odd job.

 

[Georgeonthecrescent]

Thanks @a twig . I have some araldite and a cheap Aldi version. I could use that?

 

[Georgeonthecrescent]

If that's where the fasteners go, and therefore the repair will be inside, then you're fine with the Ronseal. Repaircare/Timbabuild is only really needed externally, and especially where water gathers.
To rebuild the edge, I'd tape a plastic ruler against it (smothered lightly with vaseline or wax polish as a mould release) and push the filler against that. Makes sanding much easier. And build it up in 2-3 goes, which is easy as it hardens in 10 mins.

If I'm misunderstanding the location and it's external, you might just get away with Repaircare fine surface filler (which is one part and needs no primer, so much cheaper). That can do up top 6mm from memory, so could cover in a few fills.

Oh, and well done for renovating the windows. You literally cannot buy wood as good as that.

Thanks @mardinor . It is internal, but I wondered because of its propensity to get wet from condensation, if I needed to treat it as if it was external.

 

[mardinor]

Should be fine with condensation - go with the Ronseal.

 

[worms]

My issue with epoxy repairs is that once hardened, it can be a real pig of a job to accurately drill new holes for the window hardware. If you are trying to replace the old hardware, then there is a tendency for drill bits and screws to drift into the space beside the filler, leaving the new holes or the hardware itself misaligned. Perhaps easier if you can get the whole thing securely held in place in a pillar drill on the bench, but not easy in situ.

 

[a twig]

Agreed it’s not as easy - I’ve found punching and then drilling a pilot hole with a 1mm or 2mm drill bit first helps, and using a drilling jig if there is room to fit it but yep - not always easy

 

[Stevers]

I use polyester two part wood fillers internally where you need the filler to behave more like wood, and epoxy two part fillers outside where it's really only about survival. In conjunction with suitable preservatives and hardeners, these wonder substances allow me to make good and preserve original material and workmanship, which I think is important.