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2 awkward “Rising Damp” questions

March 2, 2011

It looks like “Rising Damp” but isn’t!!

I know many estate agents get very angry and frustrated when remedial damp companies claim a property they’re trying to sell has “Rising Damp”. Often the claim is followed by a very large quote for remedial work. This sometimes results in the buyer “pulling-out”.

However, the following TWO questions will help you query the “Rising Damp” claim. BRE Digets 245 is an authoritative guide to “Rising Damp” in walls and it’s worth a read.

Question 1 – Can I look at the results from the drill samples please?

Rising Damp” is diagnosed following the sampling of masonry dust to calculate the wall’s Moisture Content. Masonry dust is obtained by drilling holes at depth vertically up the wall to obtain a damp profile. When each drill sample’s dry weight is substracted from the wet weight and then divided by the dry weight (Ww-Wd/Wd), an accurate measurement of the moisture content of the masonry wall can be obtained. To obtain conclusive results many holes needs to be drilled.

Given the property was inspected by the remedial damp contractor while the current owner was still in possession, it’s most unlikely that permsssion was given to drill dozens of holes in internal walls!

If drill samples were not taken, you may like to ask why “Rising Damp” has been concluded, without such evidence. The well rehearsed answer may well be, “the wall has a damp profile consitent with “Rising Damp” following the use of an electrical resistance meter”. You should reply: But the resistance meter only assess the condition of the wall at the surface not at depth, “Rising Damp” by definition is a condition that requires the dampness across the wall’s thickness to be assessed!


Looks like “Rising Damp” but alas, it’s not!

Question 2 – You’ve stated that the dampness is “Rising Damp”, but what is the SOURCE of the dampness?

“Rising Damp” is merely a description of the mechanism by which dampness moves up a porous material, not a diagnosis of the source! Asking this question gets to the heart of the issue, which is finding out exactly what caused the internal dampness in the first place. Before a solution can be established, identifying the root cause of the dampness is imperative.

There are many ways the base of a masonry wall can become damp, these may include: a burst underground water main, a broken underground drain or localising flooding. It may simply be a blocked gulley outside.
If the remedial contractor can’t tell you what the source of the dampness is other than repeating the mantra “Rising Damp”, you know he’s blagging.


From → 3. Dampness

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