Survey - damp at 60% in 100yr old terrace

sunlight1

I know this comes up a lot but...got full building survey and it showed evidence of 'rising and/or penetrative damp'. There were three meter reading photos in the report, two at 25% and one at 60%. I have since negotiated £2,000 off the sale price but does anyone with experience of this think 60 would indicate a serious enough problem to pull out of the purchase?

I spoke personally to the surveyor and he said there were no tide marks or signs of the damp and it might be held at bay for a while yet. He advised not to pull out of the sale. I couldn't smell or detect obvious signs of damp when I viewed. Any help appreciated.

AdrianC

Where on the house was this "60%" (of what?) reading taken?

Damp isn't mysterious. It's perfectly predictable. Look at greenery holding moisture against the outside walls, look at ground levels higher than the DPC, look at damage to render/gutters/etc.

MovingForwards

Is anyone living in the property or has it been empty for a while?

FreeBear

Bear in mind that "damp meters" can only be relied upon to give a reasonable measure of moisture in untreated wood. Paint and other timber treatments will throw the readings out. And sticking it in to random spots on a plastered wall will not provide any quantifiable reading. To get an accurate reading of damp in a wall entails taking a sample (by drilling a hole in the wall) and placing in a small container along with a quantity of calcium carbide. By measuring the change in pressure after the container is sealed, you can then determine just how much water was in the sample.

A "damp meter", used correctly, can be used to give an indication of a possible damp area by means of taking a series of readings horizontally and vertically. But you need to be mindful that salts in the wall, different plasters, and paints will all conspire to give different readings.

To say a wall has a damp reading of 60% just demonstrates that who ever was sticking the meter into a wall has no clue on how to interpret the readings - At 60%, it would be dripping wet and blatantly obvious that there is a major problem.

sunlight1

It was in the ground floor wall, near to the skirting board. I don't know if there is a damp proof course 

FreeBear

1920s, they would have used slate, hard engineering brick, or a poured bitumastic DPC. Highly unlikely that there wouldn't have been a DPC, so the thing to look for is elevated ground levels and/or leaking gutters & down pipes.

My money would be on raised ground levels - Putting concrete down at the back of a terrace was the thing to "do" for many a year. Often, people would ignore where the DPC was and bring the concrete up to just below the level of the back door.. If this is the case, installing a linear drain between the concrete & wall will help to remove standing water from the area.

sunlight1

Thanks for all the help/replies. The 60 was the reading on the yellow meter on the photo included in the report, it's mine term not the surveyor's (I thought it was given as a percentage!)

Yes, the house has been lived in for the past 7 years and there were no obvious signs of damp.