Quote to investigate damp issue - opinions please

[Rmgcook12]

Hello

At the start of this year (Feb) I started to have damp appear on an internal party wall.

Just outside the wall - directly in line with the party wall is a shared drain. This had been been backing up so I had it inspected by the water company, roots removed and then relined in April.

Over summer, I thought the wall was drying out. The salts on the surface were becoming less and less but then over the last 6 weeks it appears to have come back even worse. I decided to get the water company out to inspect whether the drain had a leak - they've just replaced it all today. They did say there was a crack in the drain and that they repaired this.

I'm not convinced however that the drain will fix the problem entirely as I think the ground outside also needs lowering. So I decided to also get a local damp specialist in to survey the damp.

They did the following:

-Charged me £120 before they would take a look
-Told me they couldn't diagnose it without investigation but said it was unlikely to be rising damp due to the speed it appeared. Although they suggested that treatment may also include injecting chemical DPC in my wall and vertically in the party wall - they said they would confirm following further investigation.
-Suggested that I monitor it for a while now the drain has been replaced
-Sent me a the survey report (3 lines of text saying I had high moisture readings and further investigation would be needed) along with a quote for £480 to lift the floor boards, remove 1 radiator and 1 skirting board and investigate below in order to then provide a quote to remedy the damp problem.

So... on one hand I'm glad they advised that I monitor it for a while rater than jumping straight to selling me DPC (although they strongly suggested it may need this), but on the other hand, it feels quite steep to pay £600 in total for them to provide a quote for the repairs.

I did investigate local damp companies before approaching this one, and decided to pay £120 based on the positive reviews they had and the fact they said it would be deducted from many remedial work (I contacted a couple of other damp companies but they didn't seem interested in taking a look).

The close up pic (not very good angle) shows the damp when I first noticed it in February, the second pic shows the damp today (I've drawn around the damp patch to see of it changes now that the drain has been replaced)

Welcome views of others please regarding whether this type of quote is normal - if the damp persists, should I pay the additional £480 to investigate in order to get a quote to repair ? I dread to think what the final cost to remedy could be

 

[^woody^]

Any proper surveyor should be able to diagnose the cause of dampness, and any that put a moisture meter (designed for timber) on a masonry wall and exclaim "you have high moisture readings" are not proper surveyors. You appear to have paid salesmen from a firm that sells the treatment that they may recommend. And you have not been given a good service or got anything remotely worth £120 of advice

Anyway, it's clear that that damp is rising. The cause is not so clear, and you don't give enough detail to even make a guess.

But whilst a broken drain may well be causing excess ground moisture, that moisture should not even be getting up the wall. So your problem is "what's wrong with the wall to let water rise up it?"

Blocked cavity? Poor mortar joints or pointing? Plaster touching a concrete floor? The channel/cut out for the electric cable or box? Different wall materials or voids in the wall?

That section of plaster will need to come off and be renewed as its now going to absorb moisture due to the salts. But you need to find out not where water was coming from but why the damp course in the wall may have failed at that location - and fix that. Not just forget about it if the drain was in fact the source of the moisture.

 

[HERTS P&D]

Looks like the socket is leaking.

Andy

 

[^woody^]

 

[Rmgcook12]

I did think that about the plug socket Andy

Woody - thanks, all sensible points. I naively thought that paying for a 'survey', and one from a company with (some) decent reviews, would at least give me reassurance that I may get a good service. I admit I feel like I've been taken for a ride by paying £120 for a 15 minute visit and 3-line 'report'.

From what I know, the walls don't have a cavity - it was built in 1920 and is cinder block construction with cement render externally. Brick externally at the base (below ground level). There seems to be a bitumen DPC but this is below ground level outside.

I suspect this could be the reason for the damp - but then it's confusing that I have lived here for 7 years but the damp has only emerged in the last 12 months.

Any advice on finding a knowledgeable and reputable 'damp' expert? I thought I had done my homework but clearly not

 

[HERTS P&D]

Where is the incoming water mains for the property?

Andy

 

[Rmgcook12]

It's in the same location Andy - in the right corner of the photo under where the TV is.

When I had the floor up a few months back, I couldn't see any obvious leakage from the pipe.

I don't know how accurate this would be, but I've switched off the stop tap inside the room and then monitored the water meter outside - it didn't use any water over a couple of hours, so I assumed there was no leak between the supply pipe and the stop tap itself.

 

[^woody^]

The prevalence of dampness is related to the source. Supply leaks = constant and progressively worsening dampness, drains = constantly low levels, waste pipes and rain = irregular.

The old "I never got this before and ive been here 50 years" is based on false admonitions, as every single month let alone year is different in terms of weather and moisture. And ground soils have thresholds which can take years or days to reach.

Obviously ground above a DPC level is a cause of rising damp and needs to be rectified.

Anyone surveying for anything should be independent of any products or services they may recommend. Eg not damp treatment companies.

 

[Rmgcook12]

Thanks Woody. I'd say it's in the irregular space but worsened recently, then stopped over the past 2 or 3 weeks.

I'm desperately trying to find an independent surveyor to take a look, who isn't affiliated with a DPC product...

 

[sxturbo]

start by reducing the ground level outside to below the dpc course.

you want to go down at least 4 " and be around 12" wide

the incoming mains supply is this plastic? if its something like cast iron (not uncommon in the 20's) it may have rusted through, but only be weeping, not enough to show on the meter as the ground is taking the moisture in and clamping round the pipe.

 

[Rmgcook12]

Thanks Sxturbo - I don't think the supply pipe is plastic. I was told that the water company may be able to do a leak test on it - I'm not sure if the would detect a really minor leak. I can explore it as another avenue.

One thing that baffles me is that whist the ground level seems to be in line with the joists - so appears to be too high, the drain pipes are not that far below ground (having had the gully replaced recently I've seen the levels) so I'm struggling to see how the ground can be that much higher then it was when originally built.

There may be a couple of things at play - ground level and perhaps the water supply pipe too.