Scottish stone wall penetrative Damp

[SeaSocks]

Hello all,

 

Am after some advice please on how to fix the really quite bad damp that is 'flowing' through our walls in certain spots.

The build - we have a 1980's conversion with 450mm external stone and cement pointed walls, vapour barrier and timber dry lined with about 50mm of rockwool between.

On a North facing external wall we have noticed a wet patch develop on a horizontal bit of plasterboard within a window reveal, it has bowed the plasterboard in what has been an extremely wet month. I put a pad saw through it today and got a bit wet from the collected water. there was a nailed on piece of vapour barrier above the plasterboard, and extremely wet lintels and stone above it.

I'm pretty sure it is coming through the external wall and am wondering what options are, I think:

1. Check chimney flashing, pointing and cowel wich is above and about 2-3m lateral away from the inside leak.

2. Check external pointing and repair as necessary, it is cement, so will repoint with cement.

3. Some kind of porous masonry sealant?? Or will this ruin it forever? Kingfisher Stormseal or similar, though their technical datasheet says not suitable for 'dense stone' we're close to Aberdeen, the granite city...

4. Re-point and install an MVHR system.

5. Re-point and apply a lime render / harl.

 

Any advice would be extremely welcome!!

 

Many thanks in advance and happy 2024 all!