How to plaster a damp wall?

[SirGalahad]

So we had penetrating damp due to a bodged repair of a gutter which was leaking onto the sloping roof kitchen and causing penetrating damp.

The gutters have been repaired so not its onto the plaster. If you look at the pic below you can see its quite bad.

My plan is to move the cupboard and then strip all the damp plaster away from the wall back to the bricks? And also remove some from the ceiling.

Am I supposed to leave the wall to air and dry for a week before applying the new plaster.

I have read up and I am still a bit confused as to the process.

Do I use PVA bonding on the wall and then let that dry and then mix up bonding plaster and then apply that. Now as 95% of the damaged plaster is hidden behind the cupboard would I need to apply a finishing plaster ontop?

I think the whole area is about 2sq metres but I cant find anyone who wants to come out and do the job as its too small so having a go myself.

 

[NickB_99]

The gutters have been repaired so not its onto the plaster. If you look at the pic below you can see its quite bad.

My plan is to move the cupboard and then strip all the damp plaster away from the wall back to the bricks? And also remove some from the ceiling.

Am I supposed to leave the wall to air and dry for a week before applying the new plaster.

Yes, it is certainly quite bad!

As you suggest, stripping the damp plaster back to brick in that area and removing some of the damp damaged plasterboard is a good first step. I'd go a bit beyond where you can see the tide mark on the ceiling too.

I'd just see how it goes from there in terms of drying - a week may not be enough. Before a repair to the plaster I'd want to be 100% sure that the leak has been fixed.

Also putting normal gypsum plaster to make the repair will not go well if the bricks are still damp - so it must be allowed to dry.

When dry, repair the plasterboard first. For the wall patch, an alternative would be to cover with render + waterproofer to discourage any salts coming through instead.
Personally I would skim on top when you get to that stage, even though it's behind a cupboard.

 

[vinn]

Maybe you should remove the cupboard (is it a wall unit or a tall unit?) and the batton, and the jamb piece below the lintel. Then post photos of whats there.
The leaking gutter would be the upper roof gutter, and any leaking splash would land on the lower roof flashing and verge area. Photo's of that area would help.
Do you have a ventilation extractor such as a Vent-Axia in the kitchen?

 

[SirGalahad]

Maybe you should remove the cupboard (is it a wall unit or a tall unit?) and the batton, and the jamb piece below the lintel. Then post photos of whats there.
The leaking gutter would be the upper roof gutter, and any leaking splash would land on the lower roof flashing and verge area. Photo's of that area would help.
Do you have a ventilation extractor such as a Vent-Axia in the kitchen?

There is a cooker hood / extractor. The cupboard is a free standing unit. I can easily move it and then pull away the plaster.

 

[vinn]

If you do as I suggested above then dont do anything else but post a photo from ceiling to floor. Both sides of the lintel would be best.
Not a hood extractor but a wall ext such as Vent-Axia.

 

[SirGalahad]

I have stripped back the ceiling as far as I dare. The wood is rotten in one corner. Now what is the best way to repair this?

 

[vinn]

Its first necessary to solve the cause of the damp, & then to fix all the damage not just a bit. For example, the white cotton wool like stuff on some of the laths could be dry rot? Whatever kind of rot it is its simple to eradicate.
If you remove any units etc. to give a clear view of the walls to the left and right of the damaged area it would help.
Photos of the exterior, as mentioned above, would also help.
You could pull down the plaster laths and plaster ceiling back say another 600mm.
Knock off the top 300mm of plaster back to bricks. Fungal decay can move behind plaster.
Expose the lintel for about 300mm.
The roof leak has been going on for some time and moisture could have tracked further down the ceiling slope on to, and beyond the lintel.

 

[SirGalahad]

Its first necessary to solve the cause of the damp, & then to fix all the damage not just a bit. For example, the white cotton wool like stuff on some of the laths could be dry rot? Whatever kind of rot it is its simple to eradicate.
If you remove any units etc. to give a clear view of the walls to the left and right of the damaged area it would help.
Photos of the exterior, as mentioned above, would also help.
You could pull down the plaster laths and plaster ceiling back say another 600mm.
Knock off the top 300mm of plaster back to bricks. Fungal decay can move behind plaster.
Expose the lintel for about 300mm.
The roof leak has been going on for some time and moisture could have tracked further down the ceiling slope on to, and beyond the lintel.

The damp issue was caused by a leaking gutter which has been fixed. The rotten wood extends about one foot from the corner as it slopes down. Where you can see the lat that goes across with the screws that is all fine. It's about 1ft sqaure that needs repairing or replacing. Is this a job for a roofer?

Looking at the corner as it slopes down the wood beam is rotten about 1ft after which its hardened. To the left and right is wooden mahogany effect like you can see on one picture. There are no units on the wall. The walls are covered in a mahogany.

I have left the area uncovered to let it dry out as there was moisture in the wood. My only issue is whats the best way to repair it? The rest of the roof is fine and its only in that corner there was penetrating damp due to a poor gutter repair which has been fixed.

I will get exterior photos over the weekend.