replaster or not

[freewilly]

Hi , I have some salt deposits coming out above the skirting board. This is not a huge problem

as it can be brushed off easily on the odd occasion as the plaster is still good. We do ,however

suffer from condensation and possible high humidity and wonder whether replastering would

improve this. I am thinking salt attracts damp rather than creating it. I guess i'm wondering if

the pain is worth the gain. Any thoughts appreciated.

 

[cwhaley]

Goes without saying really, but it's better to solve the condensation problem first before a job like that -- re-plastering is likely to worsen it anyway as you'd be putting moisture onto the walls during the job. It might be fine now, but over time brushing off the salts will start to damage the plaster skim. I know this as when I bought my house there was a similar problem on an un-vented chimney breast.

Where are the brick salts? Is this on a chimney breast?

 

[freewilly]

Thanks for reply. No its actually on a party wall. What i'm wondering if this could be noticable contributing to the condensation. I am getting damp reading along wall but only really noticable to the eye in a couple of places where a light salt deposit is showing.Really not that damp. I have not as yet tested the bricks so not sure if damp reading is more to do with salts rather than rising damp. It really is not worth the money and mess to do anything about it unless its going to help with humidity.

 

[cwhaley]

A wall holding moisture isn't the cause of anything, it's the result of a problem. I would say if you have condensation that is what's contributing to the damp walls. Also, you won't get an accurate reading with salts (holding moisture) already on the wall. Find a clean area and test it there - plaster should be around 0.5% and brick around 1%. You could test the skirting too which should have a reading of around 10-12%.

Rising damp is a term used in excess. With it being on a party wall, it could be a few things. Is the wall plastered right down to the floor and drawing up moisture? What is happening on the other side of the wall? Cold air drops, so make sure the room is well ventilated. Do you dry clothes in the room? Need to know a bit more about what the room is used for and what happens on the other side.

If the room genuinely is well-ventilated and allowed to 'breath' and you still have damp walls, that is when you start looking deeper into it. Plastering a wall is just a finish - if you don't sort the damp you'll be re-plastering again.

 

[freewilly]

thanks cwhaley.The wall runs the length of the flat, lounge and corridor. We introduced vents and insulated some of the exteriors walls a couple of years ago. So no more mouldy walls , but did get a problem with a unit pushed to close to the wall making it go mouldy. This makes me think the humidity in the flat is excessive but can''t work out why. The reading along the wall average around 5%. Next door dont have a problem, so rising damp possible not the problem as you say. Its a ground floor flat with solid floor but thats seems dry.

 

[cwhaley]

I'd agree based on what you've said that humidity is a problem, especially as you mentioned moisture getting trapped behind a cabinet pushed against the wall. I'd also check the plaster as if it does go right down to a solid floor, it will draw up any moisture.

As for the source of the humidity, it could be something quite subtle as it only takes a couple of pints of water in a large room to significantly raise the humidity levels. Check anything from how you're drying clothes, how good the bathroom/kitchen extractor fan is and how clear the air vents are. Might not be for you, but it'd be worth looking at a dehumidifier to give you an idea of how much moisture is in the air.