Damp around chimney breast, internal and external walls

[grimreepah]

Recently purchased a semi-detached house (converted from 2 flats) in February. Originally noticed wallpaper was coming away from bottom of walls downstairs but just thought old paper, we were gonna redecorate anyway.

A month and a bit ago noticed mould growing on the back of my sofa. The sofa was on an internal wall. Dug deeper, pulled off skirting boards (plastic) and found a fair bit of damp on the wall. The floor is half concrete and half timber construction in this room and the floor is dry (cement part). All the walls in this room the wallpaper tears off easily. The plaster is touching the cement wall and the gaps where plaster should have been has been filled with what I can only describe as plaster of Paris. Behind the plaster seems to be a black coating on the bricks (about half a cm thick). The plastic skirting boards were wet when I took them off.

Most recently I pulled paper and skirting off the chimney breast and the plaster is just crumbling and more scary than that the mortar on a couple of bricks there is damp and crumbling.

Had 4 people out and told me 3 different things. Condensation, rising and penetrating from chimney.

I'm at a loss at what to do because budget is tight and don't want to spend money on something that might not fix it.

There was black mould growing on one of the outside walls. Tore paper off, cleaned it off and now seems to be drying nicely.

The plaster is damp in the kitchen too and just breaking away in my hand. Damp smell in kitchen cupboard ajacent. There was a leaky pipe there but I am unsure how long it has been leaky.

The house did have cavity wall insulation installed 7-8 years ago.

We want this fixed before we decorate, but really unsure of what to do. I just wanted advice.

Also with it being 2 flats it had a fireplace removed from upstairs. There is no vent or anything in place. This will have been done about 30 years ago when the flats got converted.

Also I have a hygrometer in the sitting room and it was 75% rh. Kept windows open and it's dropped to about 60.

Thanks for reading if there is any more info you require feel free to ask.

Thanks

Michael

 

[ban-all-sheds]

Had 4 people out and told me 3 different things. Condensation, rising and penetrating from chimney.

Unlikely to be rising.

//www.diynot.com/forums/viewtopic.php?p=2921843#2921843

There was black mould growing on one of the outside walls. Tore paper off, cleaned it off and now seems to be drying nicely.

Penetrating damp now able to evaporate with the paper gone? Was the paper painted?

The plaster is damp in the kitchen too and just breaking away in my hand. Damp smell in kitchen cupboard ajacent. There was a leaky pipe there but I am unsure how long it has been leaky.

I assume "was" implies "but no more - it's been fixed"? You need to see how it all starts to dry out. Shame you didn't move in 6 months ago

Also with it being 2 flats it had a fireplace removed from upstairs. There is no vent or anything in place. This will have been done about 30 years ago when the flats got converted.

So the chimney could be a suspect.

Also I have a hygrometer in the sitting room and it was 75% rh. Kept windows open and it's dropped to about 60.

And there's a ventilation issue.

 

[grimreepah]

Had 4 people out and told me 3 different things. Condensation, rising and penetrating from chimney.

Unlikely to be rising.

//www.diynot.com/forums/viewtopic.php?p=2921843#2921843

There was black mould growing on one of the outside walls. Tore paper off, cleaned it off and now seems to be drying nicely.

Penetrating damp now able to evaporate with the paper gone? Was the paper painted?

The plaster is damp in the kitchen too and just breaking away in my hand. Damp smell in kitchen cupboard ajacent. There was a leaky pipe there but I am unsure how long it has been leaky.

I assume "was" implies "but no more - it's been fixed"? You need to see how it all starts to dry out. Shame you didn't move in 6 months ago

Also with it being 2 flats it had a fireplace removed from upstairs. There is no vent or anything in place. This will have been done about 30 years ago when the flats got converted.

So the chimney could be a suspect.

Also I have a hygrometer in the sitting room and it was 75% rh. Kept windows open and it's dropped to about 60.

And there's a ventilation issue.

First off, thankyou for the quick reply!

I've been doing a bit of research and I was adamant it wasn't rising, but there is so much controversy surrounding it.

The walls do seem to be drying off a bit now that some of the wallpaper has been removed. Has been painted and seems really thick.

Yes. pipe is no longer leaky, but dampness is still in the plaster. There is a dishwasher in the way at the moment, but the plaster is just peeling and crumbling away from the wall.

Chimney could well be a suspect, but all the walls are damp at the bottom.

Yeah we are getting the ventilation problem sorted as we have no form of extraction. Getting a system fitted next week along with an extraction fan in the kitchen. We are getting this done first as I suffer from asthma and the missus has a dust mite allergy.

Another note, I have been unable to contact the neighbors as they have moved out within the last two weeks!

Thanks again

 

[grimreepah]

Also, the plaster around all the external walls is just crumbling off the bottom of all the external walls. Seems dry. Worst is where radiators are hung and tapped. Just falling on the floor.

 

[Burnerman]

Just a couple of things to help us get the full picture, Michael....
Regarding the floor that's suspended timber.....whats the state of the air bricks outside - are they clear, is the ground level above or approaching DPC level, are there any leaking gutters causing splash?
Elderly properties didn't have any vapour barrier below the hearths, so any damp can easily rise from there - it didn't matter in those days because people had the fires always lit!
Any plaster thats as crumbly as yours is useless and needs to be redone, but only if the dampness is cured, naturally.
The walls can breathe now with the paper off - the dampness will still be there but its dispersing quickly.
If you have a dampness meter (£20 or so from Toolstation) then test the concrete floor and see if there's dampness there.....who knows if there was a vapour barrier put in when it was laid?
John

 

[grimreepah]

Just a couple of things to help us get the full picture, Michael....
Regarding the floor that's suspended timber.....whats the state of the air bricks outside - are they clear, is the ground level above or approaching DPC level, are there any leaking gutters causing splash?
Elderly properties didn't have any vapour barrier below the hearths, so any damp can easily rise from there - it didn't matter in those days because people had the fires always lit!
Any plaster thats as crumbly as yours is useless and needs to be redone, but only if the dampness is cured, naturally.
The walls can breathe now with the paper off - the dampness will still be there but its dispersing quickly.
If you have a dampness meter (£20 or so from Toolstation) then test the concrete floor and see if there's dampness there.....who knows if there was a vapour barrier put in when it was laid?
John

The air bricks outside the timber flooring are clear not blocked at all. I don't know what I'm looking for regarding the DPC. There is concrete paving all around the outside though about 10cm below interior floor level. No leaking gutter at all and by hell we had a lot of rain yesterday to test it haha.

Yeah there is a gas fire there at the moment. We don't use it at all and thinking about getting it removed. But the damp problem is priority at the moment.

I was thinking that the plaster would need replaced. Means cold house with radiators off when getting replaced - what a time of year to find this.

Yeah the walls do seem a lot drier now that the skirting and some wallpaper is (not all - we have guests coming this month and the paper looks a state as it is we were gonna gut it off when they have left).

I have a damp meter and concrete floor seems fine. The meter is only slightly increasing. Another thing we are going to be putting laminate down, but only when this problem is solved!

Another thing, there doesn't seem to be any "tide marks" like how normally rising damp represents itself. But I am unsure of how penetrating would get all the way around the house unless all of the house needs repointing?

Thanks a lot for your reply!

Michael

 

[Burnerman]

Typically, the outside DPC is what the air bricks are sitting on.....not a hard and fast rule by any means but its a guide. Outside levels must be lower than this.
If you have cavity wall insulation, the passage through the air bricks to the under floor mustn't be obstructed - its best to have a duct in there so there is a gale blowing beneath the floor.
Its worth lifting a few floorboards I feel, and see what sort of sub floor there is.....it may be on a concrete raft which should be dry, or the floors may be earth / rubble in which case you are relying on sleeper walls, with a DPC on top, followed by a wall plate and the floor joists. Check this area is dry! (This is where damp can attack the internal walls).
Check the hearth that the gas fire sits on....that could well be damp but not soaking, naturally.
Whats the exterior condition of the building like? Is it rendered, stone or brick?
John

 

[grimreepah]

Typically, the outside DPC is what the air bricks are sitting on.....not a hard and fast rule by any means but its a guide. Outside levels must be lower than this.
If you have cavity wall insulation, the passage through the air bricks to the under floor mustn't be obstructed - its best to have a duct in there so there is a gale blowing beneath the floor.
Its worth lifting a few floorboards I feel, and see what sort of sub floor there is.....it may be on a concrete raft which should be dry, or the floors may be earth / rubble in which case you are relying on sleeper walls, with a DPC on top, followed by a wall plate and the floor joists. Check this area is dry! (This is where damp can attack the internal walls).
Check the hearth that the gas fire sits on....that could well be damp but not soaking, naturally.
Whats the exterior condition of the building like? Is it rendered, stone or brick?
John

Thanks again for replying John!

Okay so the exterior concrete all around the house is just below the bottom or the air bricks. There are air bricks all around the house but only the one is effective as all other floors are concrete.

I shall remove floorboards when I have time, but I really don't know what I would be looking for! I'll try and find what you've described though. Does smell a little soily where there are gaps between flloorboards and walls.

Hearth is not damp at all, but has a marble place on top and won't be able to remove this until fire gets decommisioned.

Exterior is brick construction with a cavity (filled with insulation via previous tenants.

I know I ideally have to get another person in, but as I say I don't want to be told something its not just so they can sell me their product. We are going to be living here for a fair few years so want it properly sorted.

Thanks again for your swift response John!

Michael