I've had a bad smell in my upstairs front bedroom for perhaps a year.
It comes on overnight. After rain it's a damp, almost mildewy smell. When it's dry it's more musty.
It seems mainly to come from around floor level in the back corner of the room. One wall in that corner is a party wall and the other is internal to my house - i.e. it's nowhere near any possible source of water ingress. The roof is fine. I've had the floorboards up and the subfloor timbers are all bone dry. No plumbing in the area. The neighbours on the other side of the wall don't have any problems. The smell is also also quite strong on the other side of the back wall of the room, from the floor inside a fitted cupboard. I occasionally get a damp smell on my stairs outside the room too.
A protimeter showed some dampness (16%ish) in the bricks behind the skirting board in the smelliest areas. But some bricks in the same areas measure 0%. There's no dampness measurable on the plaster anywhere in the room and the skirting board itself wasn't damp.
It sounds like a straightforward case of condensation. However, a hygrometer left next to the bricks overnight shows maximum humidity is normally 40-50%, occasionally almost 60% but never higher, and the temperature never gets anywhere near the dew point. Several windows are left open in the room every night, year round.
I've had two independent damp people out to look, who thought the damp readings in the bricks were probably caused by salts rather than moisture. One treated one patch of "damp" bricks with a salt treatment. However, the smelliest area is very to access as it's right at the point where one wall meets another, in a small cavity above where a beam sits in the party wall. There's also a joist running 1-2 inches away from the smelly wall which makes most of the bricks in the area hard to reach. I probably can't lift that joist without damaging the old lath ceiling it's attached to.
A structural engineer I had out last week to look at another problem (don't ask) suggested that hygroscopic salts on the bricks were causing condensation to happen at much higher temperatures than the normal dew point. Does that sound right?
He recommended sealing the bricks to stop damp air reaching them.
Specifically:
1. Where the bricks are accessible, seal with a silicone based solution than cover with an anti-salt treatment to be sure. Alternatively, just pin a plastic sheet over them.
2. Where bricks are inaccessible, fill the area with insulating spray-foam.
To treat this I'm going to have to rip out a fitted cupboard. The spray-foam in particular is also hard to undo so I'm keen to get a second opinion on whether this all sounds like a good idea before going ahead.
Any views hugely appreciated!
It comes on overnight. After rain it's a damp, almost mildewy smell. When it's dry it's more musty.
It seems mainly to come from around floor level in the back corner of the room. One wall in that corner is a party wall and the other is internal to my house - i.e. it's nowhere near any possible source of water ingress. The roof is fine. I've had the floorboards up and the subfloor timbers are all bone dry. No plumbing in the area. The neighbours on the other side of the wall don't have any problems. The smell is also also quite strong on the other side of the back wall of the room, from the floor inside a fitted cupboard. I occasionally get a damp smell on my stairs outside the room too.
A protimeter showed some dampness (16%ish) in the bricks behind the skirting board in the smelliest areas. But some bricks in the same areas measure 0%. There's no dampness measurable on the plaster anywhere in the room and the skirting board itself wasn't damp.
It sounds like a straightforward case of condensation. However, a hygrometer left next to the bricks overnight shows maximum humidity is normally 40-50%, occasionally almost 60% but never higher, and the temperature never gets anywhere near the dew point. Several windows are left open in the room every night, year round.
I've had two independent damp people out to look, who thought the damp readings in the bricks were probably caused by salts rather than moisture. One treated one patch of "damp" bricks with a salt treatment. However, the smelliest area is very to access as it's right at the point where one wall meets another, in a small cavity above where a beam sits in the party wall. There's also a joist running 1-2 inches away from the smelly wall which makes most of the bricks in the area hard to reach. I probably can't lift that joist without damaging the old lath ceiling it's attached to.
A structural engineer I had out last week to look at another problem (don't ask) suggested that hygroscopic salts on the bricks were causing condensation to happen at much higher temperatures than the normal dew point. Does that sound right?
He recommended sealing the bricks to stop damp air reaching them.
Specifically:
1. Where the bricks are accessible, seal with a silicone based solution than cover with an anti-salt treatment to be sure. Alternatively, just pin a plastic sheet over them.
2. Where bricks are inaccessible, fill the area with insulating spray-foam.
To treat this I'm going to have to rip out a fitted cupboard. The spray-foam in particular is also hard to undo so I'm keen to get a second opinion on whether this all sounds like a good idea before going ahead.
Any views hugely appreciated!
