I'm after a bit of advice to do with our damp floors and a new underfloor heating system.
We've just bought a late 1950's bungalow which has concrete floors with a damp problem and slight slab subsidence. The walls are fine and solid with no cracks or signs of movement, but the floors have dropped by up to 20mm in places or have cracked. Pretty much the entire property suffers from this to varying degrees.
Despite being built in 1957, the builder obviously cheaped out on the build as we have solid walls and most of the slabs have subsided indicating a substandard sub base.
There is a DPC in the walls which looks like bitumen, but I suspect there is nothing in the floors due to the amount of damp that comes through. If it's been raining, you know about it inside within a short time as everything in wardrobes and cupboards feels damp. I took up the carpet in one room and the floor was covered in condensation over the vinyl tiles below within minutes. I suspect that these tiles with a tar adhesive has offered some damp protection over the years.
Pretty much the entire downstairs is suffering from damp, but the front is the worst because of a suspected blocked rainwater drain. Since fixing the guttering the damp problem has improved slightly, but now it's getting wetter again we've noticed the damp returning. Some patches of wall damp haven't returned yet so that's a positive at least.
Currently, it's approx 95sqm and we hope to extend downstairs by approx 75sqm and add an upstairs within (new) roof space to create a 1.5 storey home. We've got a tight budget and we'll be doing a lot ourselves to keep the costs down.
Now, onto the solution which hopefully you knowledgable folks can help with. We want to add underfloor heating so do we take up the existing concrete or cover it up?
The wall DPC is at the same level as the current floor level and it isn't joined into anything in the floor. We're planning on removing most of the existing roof apart from one section which will remain single storey so we're planning on retaining it. Could we simply lay a new DPM on the floors, add insulation (say at least 70mm) then the underfloor heating and finally a screed? This will obviously take the floor level approx 150mm higher than the wall DPC, so will this cause a problem? Can it be avoided by running the DPM up the inside of the walls a little, or am I being plain stupid.
As the roof is coming off we could raise the ceiling heights in most rooms to compensate for the floor being raised pretty easily. Many internal doors will be moved, but those that remain can be lifted easily.
Or, would it be as cost effective to remove the entire existing slab, lay an new concrete floor with new DPM and insulation? I imagine the slab has moved as much as it is going to given it's been there now for 50+ years.
We want to get it right as obviously it's a major part of the building and for that to be wrong now will be even harder to resolve once the project is complete.
Cheers,
Jon
We've just bought a late 1950's bungalow which has concrete floors with a damp problem and slight slab subsidence. The walls are fine and solid with no cracks or signs of movement, but the floors have dropped by up to 20mm in places or have cracked. Pretty much the entire property suffers from this to varying degrees.
Despite being built in 1957, the builder obviously cheaped out on the build as we have solid walls and most of the slabs have subsided indicating a substandard sub base.
There is a DPC in the walls which looks like bitumen, but I suspect there is nothing in the floors due to the amount of damp that comes through. If it's been raining, you know about it inside within a short time as everything in wardrobes and cupboards feels damp. I took up the carpet in one room and the floor was covered in condensation over the vinyl tiles below within minutes. I suspect that these tiles with a tar adhesive has offered some damp protection over the years.
Pretty much the entire downstairs is suffering from damp, but the front is the worst because of a suspected blocked rainwater drain. Since fixing the guttering the damp problem has improved slightly, but now it's getting wetter again we've noticed the damp returning. Some patches of wall damp haven't returned yet so that's a positive at least.
Currently, it's approx 95sqm and we hope to extend downstairs by approx 75sqm and add an upstairs within (new) roof space to create a 1.5 storey home. We've got a tight budget and we'll be doing a lot ourselves to keep the costs down.
Now, onto the solution which hopefully you knowledgable folks can help with. We want to add underfloor heating so do we take up the existing concrete or cover it up?
The wall DPC is at the same level as the current floor level and it isn't joined into anything in the floor. We're planning on removing most of the existing roof apart from one section which will remain single storey so we're planning on retaining it. Could we simply lay a new DPM on the floors, add insulation (say at least 70mm) then the underfloor heating and finally a screed? This will obviously take the floor level approx 150mm higher than the wall DPC, so will this cause a problem? Can it be avoided by running the DPM up the inside of the walls a little, or am I being plain stupid.
As the roof is coming off we could raise the ceiling heights in most rooms to compensate for the floor being raised pretty easily. Many internal doors will be moved, but those that remain can be lifted easily.
Or, would it be as cost effective to remove the entire existing slab, lay an new concrete floor with new DPM and insulation? I imagine the slab has moved as much as it is going to given it's been there now for 50+ years.
We want to get it right as obviously it's a major part of the building and for that to be wrong now will be even harder to resolve once the project is complete.
Cheers,
Jon
