Repairing red sandstone window surrounds

One of the window surrounds has quite a bit of weather damage to it. no cracks, but a reasonable amount (about 5mm depth 100mm long scab) of crumbly stone at the surface.

Just the one side of the window, I’ve brushed it back to more competent stone to see how far it goes and doesn’t appear to have rotted the whole lot, just surface ish.

once I get it cleaned up properly, can I just fill with lime mortar, either with red pigment and/or red sand, or should it be a little more involved than that.

We’ve left the sandstone unpainted up until now, pressure washing them a couple of times a year to remove green staining etc. This seems to keep them in order, apart from this one window. Should I really be masonry painting them to add a bit of protection?

Advice greatly appreciated.

ta

You could protect them with a clear coat just as easily. Sovereign do a weather check facade cream. Brilliant stuff but pricey. Think Thomsons water seal but 10x better.
As for the repair it’s not as simple as you think. A true colored epoxy affair would be better as a mortar will no doubt blow after time with frost thaw action.

You’ve been pressure washing your sandstone surrounds? Sandstone is the softest rock. The surface weathers and hardens but once you break that surface you expose soft stone, as any rock climber in south-east England knows.

If there’s really no alternative, you can buy stone protector, which you brush on. Not sure if it’s waterproof though; why don’t you find a local stone mason or monumental mason and ask their advice?

We do a lot of bank stone repairs, I typically see any repairs blowing in 3-5 years – best to replace when it needs to be done

You’ve been pressure washing your sandstone surrounds?

well, not quite as harsh as it may sound. normally washing off green algae/lichen remover, so not a 1″ off the stone type affair.

Replacing the stone isn’t a financial option currently, so a repair is the only way to go. I was hoping there was something I could probably do myself rather than involve a 3rd party, especially on a small bit like this.

it’s Scottish ORS if it helps, slightly different to southern ORS, but still not 100% weatherproof ;-)

ta

Don’t use a weatherproofer, it’ll stop the stone breathing as well and will in all likelihood cause more spelling of the surface in the future. You can do a lithomex repair, which is lime based and breathable, and can be combined with stainless steel pins depending upon the repair thickness and finished to give the impression of tool marks. The Scottish Lime Centre are good for advice, or speak to an experienced stone mason.

Edit: don’t use masonry paint, you’ll wreck it even more!

ok, thanks.

That’s it I give in!

you do?