CHEMICAL DAMP PROOF COURSE - IS IT NECESSARY?

[ianblue]

We recently bought a house which had had a survey carried out by timber restoration company ( The experts)
They condemned three of the room floor as having wet rot, plaster was to be removed and replaced to a height of 4 feet and a chemical DPC was to be fitted. Cost £5000.
In one room it was perfectly obvious to anyone that a number of joist ends were rotten as the floor had dropped 1/2 inch below the skirting board. I measured the moisture in the plaster ( lathe and plaster) and found this to be high.
Checking around the house I found that the lawn level had been raised against the back wall. This should be 150 below the vent. Apart from the splash the long grass in summertime would inhibit passage of air into the vents. Checking under the floor ( 3 feet clearance) I found that the vents were totally blocked. Also the passage of air from the solum up the cavity behind the lathe and plaster.
Also I admit I have been sceptical about the phenomenom of moisture rising up through brick walls but I think this photo shows the DPC working effectively. The brickwork below is damp but the bricks above are clearly dry.
I have now cleared all the vents, lowered the lawn back 300 from the wall and replaced the joist ends in one room together with the infected floor boards. Cost £65 . The walls are now showing normal moisture content.

 

[themiddleagedun]

Your investigations and subsequent actions seem "spot on"
Well done. You've just saved £4935!

 

[bobdabuilda]

what picture?

 

[ianblue]

what picture?

Sorry I fiddled around for ages trying to attach a couple of pictures without much success.

 

[joinerjohn]

Pictures are on the OP's profile.
Just out of interest, who were the firm of expert damp proofers you had the quote off? Could help others to beware of them.

 

[ajrobb]

In album, click on picture and copy 'DIYnot BBCode' field value:

DAMP PROOF COURSE

• ianblue
• 13 Dec 2010
• 1

DOES THIS SHOT PROVE THAT THE DAMP PROOF COURSE IS WORKING

VENT

• ianblue
• 13 Dec 2010
• 1

THE VENTS WERE TOTALLY BLOCKED!

VENT

• ianblue
• 13 Dec 2010
• 1

AAAAAAHH, THAT'S BETTER. FRESH AIR!

 

[chapeau]

Got a victorian solid wall property, lovely house it is, but the kitchen floor has been raised in the past which seems to have bridged something and recently getting visible damp in internal wall. House not been lived in for a couple of months and I guess these old houses needs heating and ventilation to breathe properly.

Anyway, want to flog the house so I called in a few damp cowboys to do their moisture meter snake oil tests, really just wanted a guarantee to show any purchaser as their surveyor would have spotted it and hopefully this will tick a box to make it easier to sell in this market.

However the Cowboy also decides to quote for a new injected dpc on all external walls and details this recommendation in his survey. He includes cost for same.

Unfortunately for him, his company injected dpc into the very same external walls 25 years ago and I dig out the 30 year guarantee. Scan it, email it, ask him to requote excluding the external walls as he will be doing that work for free.

After a few chasing emails get a reply saying he will need to come in and do carbide testing on wall and salt testing on plaster (£110 + VAT charge to me) and depending on the results he will agree the external walls require a new dpc putting in.

So, the original question.

Chemical Damp Proof Course - Is it neccessary?

Answer.

Only if the feckers don't realise that if they recommend it they will be paying for it.

The saga is ongoing and this company will lose. National company too, not yer local cowboy outfit, it's a big one.

 

[ianblue]

Also I admit I have been sceptical about the phenomenom of moisture rising up through brick walls but I think this photo shows the DPC working effectively. The brickwork below is damp but the bricks above are clearly dry.

NO IT DOES NOT!!

I have just answered my own question.
The problem I had was at the back of the house. This photo from inside the solum is of the front wall where there is no problem.
Since there was no problem I did not bother to check any further. Now I have just noticed that the ground is level with the DPC. Therefore it stands to reason that the bricks below that level would be damp but it does not prove that if the DPC wasn't there the courses above would be dry anyway!