Rising damp found on survey

[Hummingbird33]

Had a full building survey on a house we are buying, a standard semi from around 1930.

The surveyor reported dampness which might be rising damp to the front of the house on the ground floor. There is one area around a chimney and one near the front door.

Mentioned this to the EA and they got in their "Independent contractor" the next day, who detected it in the same areas and quoted about £1k + VAT to rip off the plaster and install chemical damp proofing.

I think we could do with a proper Independent damp survey but we are reluctant to spend the £400ish at this point (other issue outstanding).

I am no expert but I think it would be best to establish the cause of the dampness before doing anything to it, i.e. the chimney needs checking and the water pipe outside the other patch. Also I'm sceptical about the merits of chemical damp proofing.

Seller says he won't cover the cost which has been quoted, but would allow for the work to be done between exchange and completion.

The whole house has been recently plastered / decorated in preparation to sell and the condition of it was one of the setting points, so I'm not too happy about the prospect of disruptive work to fix this if it can't be done before completion.

WWYD / anyone had similar?

Had damp in my first house, a 30's semi. It was caused by blocked air bricks reducing ventilation to the under floor void. It's very common in houses of that age. Takes about 3 months for the new plaster to dry.
Often, also, you get the soil in a flower bed against the wall blocking thé air bricks, too.
Wouldn't put me off, tbh.

Exactly the same here. Damp surveyor said damp throughout and possibly needs new subfloor in one room or could be just new shims and a chemical damp proof course. (Funnily enough the same as a previous surveyor on a previous house) both house circa 1900. Negotiated ££ of house price.
We’ve moved in and honestly cannot see, feel, smell any damp except where an air brick is partially blocked (easily cleared.). Yes, the floor bounces a bit, where it’s always walked on in front of the door. But that’s it, just the one floorboard. So suspect new shims and maybe a new joist at most.

It is my understanding from experience and a lot of subsequent research (I am NOT an expert at all). That chemical injected damp proof courses fail very quickly and cause a host of other problems in old houses and just serve to empty your bank account. Whereas good ventilation and warmth without adding damp (through laundry etc) serves an old house much better, as they are built with in and with different maintenance needs to a new build house. Basically if you wrap them up in plastic without allowing them to breathe, they will rot from the inside out.

as I said - we aren’t expert or work in this field. This is just from our personal experience.

You might want to get @pigletjohn 's views on chemical damp proofing.

The whole house has been recently plastered / decorated in preparation to sell

This would be a red flag to me. I'd assume they know there's a damp issue and have tried to cover it up rather than fix it.

My understanding is that rising damp is very rare, and chemical damp proofing is a bit of a rip off.

Damp is usually because of, as PP have said, a blocked air brick, a leak from a gutter, pointing or flashing that's failing, or the original damp proof course being breeched (this can happen when soil or something else get's built up over the damp proof course). I'd go back and take a really careful look at the outside of the house and see what you can spot.

In an old house of ours when we were young and naïve we paid for damp treatment. Turned out it was some badly laid lino that water was getting trapped under. Once we ripped it up the damp was solved.

Before you turn to chemical damp-proofing.....

1. check the flashing around the chimney breast
2. Check gutters, downpipes and drains are all clear
3. Check the pointing in the brickwork above and below the damp course. If it has gone soft/crumbly, it may need repointing
4. check that airbricks are clear.

I've just had two areas of rising damp dealt with in a similar aged house, cost around £1,500 and came with a 20 year guarantee.

It wouldn't necessarily put me off another property but I'd need to have it properly dealt with before doing anything else.

Anywhere They've recently had skimmed will have damp, pretty much guaranteed. I have it in a couple of other areas but given a buyer will potentially want to rip out the kitchen and/or take out walls it's best left as a negotiation point.

Thanks to all who replied :)

So the chemical damp proofing contractor has just said that the damp they detected is relatively minor and they are sure it's rising damp around the chimney because it is only from the ground to around 1m. I still don't understand why it would just be damp on that part of an internal wall if there's no chimney leak. I also don't think that chemical damp proofing is the right thing to do.

It did occur to me that they might have covered up issues elsewhere when they decorated, but there was no damp detected elsewhere, no smell of damp and no visible signs of it.

Again I am no expert. But have had a lot of chimneys in various houses and boats. An old sweep said chimneys catch colds like children. They are cold sinks - being large lumps of brick work of solid construction - and cold can feel damp.
Which I suppose if you think about it in terms of laundry is true - in the winter it gets harder to tell if your line dried laundry is dry or merely a touch damp.

having said that - make sure your chimney is sound- pointing and flashing, capped or a bird cowl etc. As rain water travels downwards through the tiniest crack and will collect at the bottom of the chimney adding to damp issues.

Maybe I should get a builder to check the chimney?

You could. You could get a good eyeball just using a pair of binoculars. You could ask a chimney sweep to check it out too.
Or accept that it’s part of maintaining the house and always will be - weathering never stops….
Personally I see it as planned maintenance like clearing gutters annually and sweeping the flue. 🤷‍♀️ Preventative maintenance is cheaper than a chimney pot or stack deciding to make friends with the ground.

Do not let the person from a damp proofing company anywhere near your house.
Rising damp is so rare that it virtually doesn’t exists, especially in a house built from the 1920s.
I’ve been a developer for the last 10 years and I’ve never came across ‘rising damp’.

So you’re absolutely right that chemical damp proofing is not the right thing. A house built in the 1930s will have a dpc similar to a house built today. So it’s unlikely to be an issue with your damp course.
Investigate the area outside to see if anything might compromise your damp course. Checked if air bricks are visible.
there could be an issue with your pointing, gutters or something introducing water to the area.
Whatever it is, get that sorted first.

A house built in 1930's will have had a DPC, most likely slate.

Slate lasts at least 400 million years.

Damp at the base of a chimney is often caused by builders rubble thrown into a bricked up fireplace, or one that is not ventilated top and bottom. Sometimes rain gets in at the top.

Is the other patch anywhere near a drain or pipe?

Chemical injections will not repair building defects.

@PigletJohn Yes, where the second patch is there's a pipe on the outside of the wall coming down from an upstairs bathroom above.

The "independent contractor" said that they didn't note any leak from the pipe but I'm not sure that they actually checked it.

If the contractor makes their money from selling useless chemical injections, they might not be very interested in leaking pipes, broken drains or dripping gutters.

I mean I live in a cottage in the Lake District so everything’s damp. 😂 Would not bother me really.

I live in a 1930s house, you can see the slate damp proof layer as a thin dark line a few brick courses from the ground. We had damp in a couple of places for different reasons. Fortunately our surveyor was of the opinion rising damp wasn’t a thing and looked for actually reasons for the damp and gave us sensible suggestions. We had to lower the ground level at the back (old patio was built well above damp proof level) and clear the air bricks. We also had a French drain added for extra protection. No damp at all now. Cost a fair amount for the new patio but the rest was inexpensive. Surveyor said 9 times out of 10 it’s ground level too high or leak from gutter /roof or a pipe. An actual ingress of water rather than “rising damp”.

Chemical courses are particularly useless in old houses with cavity walls. The stuff just sits amongst the debris in the cavity doing nothing.

Rising damp is a bit of a con usually

Get a damp surveyor in who doesn't sell treatments, it's very likely water making it's way in somehow a silicone injection won't fix the cause and will probably be more expensive than a proper fix

Thanks all, it's helpful to see that most people wouldn't be too concerned and agree that chemical treatment is not the way forward!

I think we'll probably not worry too much about it and look into getting the cause checked by someone independent after we move in.