"Damp" internal wall - initial measurements made. Any ideas?

[Clive Long,UK]

"Damp" (condensation?) wall

Hello,

A brief description. The lower part of an internal wall in a purpose built flat is suffering from "damp". The wall paper has lifted way. there is no mould growth.

Now I have borrowed a Protimeter (damp meter) from a surveyor friend , taken about 100 readings and I am reading the excellent "Dampness in Building" Oxley / Gobert ISBM 0-7506-2059-5.

To summarise what I have found.

The wall is 7.60m long, 2.35m high. It is a "shared" (with adjacent flat) internal wall, probably load bearing as concrete lintels cross it at right angles. The composition is (probably) brieze block with a plaster skim (as in rest of flat). There is a soft-wood, 9cm skirting and the floors are solid concrete skim with vinyl tiles. On top of the tiles is Dunlop underlay and wool/nylon carpet.

Left-Hand end of the wall is adjacent to the front door that opens to an internal hallway in the block, not directly outside. Right-hand end of the wall is adjacent to, and at right-angles to, another internal wall that is tiled bathroom wall on the other side.

I have taken "damp" readings at 25cm horizontal intervals and 10cm vertical intervals (what a tedious job !!).

Results: At LH end by front door, the skirting and wall register between 11 to 13 ? this is not a concern to me.

One third of the way from the RH end, opposite a large double-panelled radiator the damp registers as follows.

The skirting measures between 17 to 24. The skirting is more damp the closer the reading is made to the junction with the floor.

The wall immediately above the skirting measures between 20 to 50. The highest wall reading occurs directly above the highest skirting reading. Question: Could the high conductance be due to damp wall-paper rather than the plaster?

The damp reading diminishes rapidly vertically to a level of 12 to 14 at a height of 30 cm. This value is for any position along the wall, including the most damp areas just above the skirting toward RH end

At any height above 30cms the wall measures 12 or 13.

Initial thoughts

1. The radiator is causing the problem. But how? And what to do? I can't move the rad.
2. Damp is coming from the floor. How do I investigate that further?

Any ideas on what to investigate next to try to isolate the problem before I call someone in who may attempt the wrong treatment because they haven't understood the cause ?

Many thanks

Clive

[John Rumm]

Do you know what is the other side of the wall? (for example a bathroom, a radiator, aquarium ;-) ?

Well it can be - those meters can be rather notorious for measuring all sorts of unexpected things if you don't pay attention to how you are using it (i.e. conductive wallpaper, surface moisture, cinder block (i.e. high carbon) wall construction). They were originally designed for making measurements in timber - for which they are quite accurate - hence your comment about a high moisture content on the skirting would seem to indicate more than just surface moisture.

The radiator itself may not be a problem - you would probably see water dripping / spraying out if it was leaking - possibly even rusty water stains, but where do the pipes go?

For example, a set of pipes buried in the concrete floor can be a soggy mess waiting to happen if the pipes were not adequately protected before being concreted over.

Short of drilling a hole and analysing the water content of the dust removed by the drill - tricky.

Look for the obvious causes first. So called "rising damp" is very rare in reality - almost unheard of in modern building materials. Penetrating dampness from the other side of the wall is far more likely. So check that with the neighbour (also finding out if they have the same problem (or a less or more severe version of it) would help. See if you can trace where the radiator pipes go as well.

[Clive Long,UK]

John / All

My resp>

On the other side is another narrow hallway with no furniture nor radiator. The flats are "mirror image".

Well the wall I think is this "high carbon" material covered with plaster skim. When I have drilled into it in the past it is a black material that disintegrates when assaulted by a hammer drill. However, the depth I am pushing in the probes of the Protimeter make me feel I am only measuring conductance through damp plaster.

The radiator is on the OPPOSITE wall to where the damp is - I did not make this clear. Also all pipes are "surface mounted" on the skirting and not leaking. The reason I mentioned the radiator is that the Oxley book gives a scenario where hot "moist" air from a radiator rises then moves across the ceiling, cools, drops down the opposite wall, cools more until the wall temperature is dew point and the moisture in the air condenses into the porous plaster.

But maybe if I lift the carpet and underlay, and some vinyl tiles. If there is an obvious source of damp the underlay should be damp at this point - and I can try to measure the dampness of the concrete screed. Thoughts ???

I have tried getting access to the neighbours property on 3 occasions. He just says he doesn't have a damp problem and won't let me in to measure. There are other issues around not getting access not related to investigating damp. If I can get a solution to the "damp / condensation" problem that then puts him in a position where he has to be more co-operative - then that will be a satisfactory outcome. I won't do anything that will deliberately cause a problem for him.

As mentioned above, routing of radiator pipes is not an issue as they are all surface mounted.

I'm happy to pay a professional to cure the problem - but I need it properly diagnosed. I get the impression that a lot of the "Professionals" are quite the opposite - which is why I am performing the initial investigation myself and I will be in a better position to ask "why?".

[Lee Blaver]

Clive Long,UK wrote: snip

Ask the freeholder to take a look? Unless you are in scotland...

Well that might negate asking the freeholder then ;)

Lee

[John Rumm]

Oh well that eliminates some possibilities...

If the plaster is dry then they would be unlikely to make much difference - however they will tend to make a slightly damp wall look more damp than it is - think of the plaster as a medium value resistor and the cinder block as a low value one wired in parallel with it.

OK not that then

Would have to be in quite a damp environment I would have thought - if the whole room is heated then the amount of dampness in the air to circulate should not be that high unless there is an unventilated adjacent shower room that is adding lots of moisture to the air.

May be worth doing... How far are you from "outside" at this point in the building?

Some flooring materials (like the lime putty based stuff the use in some places) can be quite hygroscopic - sucking water up from adjacent sources.

I also suspect that many so called damp proofing "specialists" are nothing of the sort - the whole industry seems to be somewhat questionable in many cases (aided and abetted by the mortgage lenders / surveyors as well!)

It strikes me that this would be an easy job to end up "fixing" without ever finding the actual cause. This would only tend to hide the problem though. For example the usual damp proofing company fix of hacking off the plaster and replacing it with render containing a good amount of PVA then skimming over, and pressure injecting a DPC along the base of the wall would keep your side of the wall dry - might make the problem worse (if there is one) on the other side though. If the problem really was condensation then this could make your problem worse.

Nothing to stop you getting a few of the "damp experts" to give you their view / estimate - you never know you may find one that knows what they are doing.

[Meoww]

snip

Presumably the flat is modern?

Does this problem occur all year round or is it just in the colder months?

Is it causing degradation of the decorations?

If you're reading oxley, you'll know that rising damp will give a reading showing a rapid cut off approximately one metre above the floor level, is this what it's doing?

I had a very similar problem a few years ago in an end terrace. The wet wall was a gable wall at the bottom of the stairs. Next to the bulding and separated from the gable wall by no more than nine inches was another building. This ruled out penetrating damp because the wall was protected and rising damp wasn't an issue because there was a basement and this wasn't damp. I finally figured out that the gable wall in question was being ultra cooled by the draught blowing through the gap between the two buildings and, because there was a radiator at the bottom of the stairs, this was causing severe condensation. Double glazing compounded the problem of course and in the end we moved the radiator.

You say that next to your problem wall, in next door's flat, is a corridor without a radiator. It's a posibility that this too is a very cool area and your wall is consequently losing heat to it and becoming an ideal condensing surface.

If this only happens in the colder months then condensation is your prime suspect! However, if the moisture content of the skirting is above 18 percent wme then it's in danger of rotting.

Patick