Help with stone lintel above window

[Jblakes]

Afternoon all,

As I was removing the aerial I went to pull it outside and found the previous person had filled this gap with cement and so had a failed and damaged the stone (sandstone I think). Anyways how best to sort this. Fill the hole with lime mortar and stones? What do I do about the lintel is looks abit of a mess.

Kind regards
James

 

[Cubist]

Two challenges here I think. The first being how to fill the void above and behind the window frame while creating a strong enough base to support the use of a a suitable sealing material to make the joint between the new material and the window frame watertight against driven rain. Personally I would be thinking about using a strainless steel chickenwire mesh shaped and firmly pushed into the void to create a tight fitting armature/skeleton into and over which I could then apply a two part, resin based, filler that bonds well to the extant stone. Injected to troweled into place this will close the void and create a strong base that will accept a sealant for final closure.

 

[Jblakes]

That's sounds like a good idea. Do I need to cover the stone with anything? It looks like it eroding away, obviously need to stop it

 

[Cubist]

I would be wary. It looks like some clot may have painted the surface of the lintel in the past. They may have used a plastic paint of some kind that has trapped water in its surface and nature has then taken its course of the surface stone has blown off. Best action, I would suggest would be to clean off all the surface paints back to raw stone and then leave it to dry for a while. Once your repair to close the gap is complete you might consider a lime wash or distemper finish for the future.

Please be aware that stone sealants can also cause water to be trapped to the induce further spalling/erosion of the stone.

 

[Jblakes]

Yes it looks like some crappy paint, on all the lintels Ive removed what I can, need to figure out how to remove the rest.

I wouldn't use a sealant I was thinking lime wash but unsure how well it holds up in heavy rain

 

[Cubist]

A heat gun may be your best option and I would definitely shy away from any kind of chemical stripper.

Lime wash stands up to the weather particularly well. It can get a little grubby looking on Northern and Western exposures that get little direct sunlight but a quick brush down with water soon shifts that and removes any loose, flaky old wash. Also, if you make your own, it's ludicrously cheap and a quick freshen up is rapid and easy.