Damp on internal wall

[paul_round]

I have an Edwardian house, which has had a couple of extensions over the years, (previous owners, possibly the 70's or 80's). I am getting damp issues on one internal wall between study and lounge, (extension). The room in question has a concrete floor, I have removed the skirting board and the plaster goes straight to floor. Using a moisture meter I am getting readings around 20 at the bottom of the wall, halfway up, I get 7. I have removed some of the plaster at the ground level and there is no DPC. The wall in question is 12" thick, so I suspect may have been one of the original outside walls.
Any suggestions as to a course of action? What about a chemical DPC injection?

 

[bobasd]

ask mods to transfer this to buildin forum.

any DPC might have been bridged by the concrete floor bein laid with no membrane.
whats happenin on the other side of the wall - is that a solid floor to?

you could hack off plaster tosay 700mm - 800mm height an replaster with a lime render.
for what its worth you could also drill the same hight bed on both sides of the wall an inject injection cream.

is the back of the skirtin rotted?

 

[paul_round]

The other side is floorboards, but same moisture readings. The skirting board is in good condition.
Also, as a comparison, my outside walls don't give a reading higher than 8, so this issue is confined to this one inside wall.

Silly question, but how do I ask the mods to move to the building forum?

 

[jj4091]

I have reported to mods for you to be moved, but wanted mention that as far as I know there should be a 2 inch gap between the concrete floor & the start of the plaster & also is it possible that you have a cupboard or something similar close to the wall as that can cause condensation that might show up as dampness.

 

[paul_round]

Thanks for that. I know about the gap after reading the many posts on here about damp, which is why I pulled the skirting board. No cupboard.

 

[foxhole]

In extention where outer wall becomes an inner wall failure to close correctly at roof level causes damp at ground as the moisture falls thru the structure and eminates thru wall once it can travell no further [dpc].
You tested wall with meter?, impossible to detect damp with any meter [you probably have one for timber] unless a core sample is taken, anything detected at surface could be condensation.

 

[paul_round]

Its definitely not condensation. The wall adjacent to it, which is an external wall, has much lower readings.

 

[foxhole]

Its definitely not condensation. The wall adjacent to it, which is an external wall, has much lower readings.

The readings from a meter intended for timber use? are meaningless.

 

[JohnD]

damp, internal wall, concrete floor, Edwardian house

likely a plumbing leak.

Have you got a water meter?

Does your boiler have a pressure gauge?

Does the old lead incoming water main pass under that floor?

Or a radiator pipe?

 

[paul_round]

Not a plumbing leak, the meter has settings for wood or brick.

 

[JohnD]

How did you find out there is not a leaking pipe or drain buried under the ground near the wall?

 

[paul_round]

I know where the mains pipe is routed, same with drains, so I know its not that. I can't see anyway it could be a buried pipe either.

 

[Ian H]

My job today showed as damp on an internal wall (side of the chimney breast), turned out the soil vent pipe rest bend was leaking 5 or 6 meters away.

Have you looked under the floorboards at the other side of the room?

 

[Bonni]

Walls do not keep water or damp out. A solid wall MUST be lime mortar, has the outside ever been repointed with cement mortar? Cement mortar is the worst thing for a solid wall, moisture soaks into bricks/stone and evaporates/breathes out the mortar. Cement traps the moisture in.

Secondly, 99% of damp problems can be cured by making sure the ground level is 6 inch below DPC. People often lay new paths without clearing the old.

Floor slabs should be laid on a 1200g DPM sheet and 25mm upstand of Kingspan between the slab and external walls.

Any of those above not adhered to can/will result in damp issues.

 

[bobasd]

ianh
how do you now that the damp signs on the c/breast an the leakin rest bend were connected?