99% damp reading in kitchen floor

[Bobbleka]

I have had an offer accepted on a house and the survey has come back with a 99% damp reading in the concrete kitchen floor. The other floors are all exposed, just bare floorboards. Its a 1930s end terrace which has been empty for over 2 years.

The survey said it is most likely that the concrete was laid without a membrane, and would need digging up and relaying with the membrane.

I’m just panicking a bit in case its a leaking pipe under the house or something. The house is perfect in many ways so I am hoping it is not this. 99% damp sounds crazy though!

The vendor doesn’t live here, it was their parent’s old house but he doesn’t know anything he can tell me.

Other slightly high damp readings were by the patio door in the reception room, but no rising or penetrating damp noted in survey.

I was so excited but I’m so worried now.

Are there any signs other than the moisture meter reading to suggest there is a damp problem? I think the meters usually just measure the electrical conductivity and guess the moisture level based on assumptions about the composition of the material. Different concrete mixes can give results that vary a bit.

Also, how certain are you that the floor actually is concrete? We live in a 1930s house and found the kitchen floor was made from a compacted mix of lime and ash or something. I'm willing to bet that would have given a VERY odd result from a damp meter!

It could be a leak on the service pipe inder the house from the street, with the internal stop tap under the kitchen sink. If the property is 1930s then there's chances that it's made of lead anyway and would be worth replacing to improve water quality and possibly pressure and flow.
FWIW- we had a leak under our house. It was like a lake below the floorboards!

We were in a similar situation with a house we were buying a few years ago. It was a 1930s semi. Some years back the floorboards in the lounge had started to rot so the vendor had tipped a load of concrete over the floor without putting down a membrane or doing the proper prep. The damp meter readings were through the roof. Couldn't ignore them.

Fixing things would have meant digging out the old floor and replacing it which would have been costly and messy so we were going to get someone in to have a look and advise. The vendors threw a hissy fit and took the house of the market!

Shame as we would still have bought the house, just would have had to factor that into the budget though.

99% damp reading in the concrete kitchen floor.
Google tells me that "anything above 16% is considered damp". Surely 99% is practically water!
Is the reading correct?
Or do I not understand how the meters work?

I could t believe it was correct either but I phoned the surveyor and he said it was definitely so but said yes it was unusual. I am arranging for a damp survey as well and another visit with a builder and plumber for that and some other work so will have another look and look at what the floor is made of. It’s just a crazy reading. Might give the surveyor another call to find out how he measured it.

I offered on it being a doer upper but just thrown by the high reading. Thanks for replying.

I've just moved into a 1930's bungalow and did have a L3 RCIS survey but you can't lift carpets. I'm just packing everything up again to go into storage because all three floors of the bedrooms, the hallway and bathroom are black with mould. The only good floor is the concrete kitchen/lounge extension.

The surveyor can't work out why until the chipboard is taken up, but cut a hole in it on Friday and said the joists are soaking, but luckily not rotten. Water is somehow getting under the building. All of the floors are going to be taken out and I think I'll have to go concrete, timber is so expensive at the moment.

My neighbour next door also had a L3 survey and did have damp found in her concrete kitchen floor but she didn't act on it at the time and had her new kitchen fitted and vinyl laid. Unfortunately it's got worse, she's having it all dug out in April and redone. Her garden is different to mine and slopes downwards towards the kitchen at the back - in Storm Arwen the water was rising towards her patio doors.

Do make sure you get an independent damp specialist, not a PCA surveyor who wants to sell you a dehumidifier and other expensive short term solutions.

Oh no @Salome61 what a nightmare! I hope it’s all sorted soon! Part of me perversely wanted to ignore it and yet my head int he sand as it’s so stressful. But I’m going to contest damp specialists today.

That's wise @Bobbleka, my neighbour is having to have her new kitchen ripped out, and the vinyl is ruined. I do hope you can find an independent damp specialist, for 'good will' I was persuaded by my EA to pay the £300 fee for my buyer and his mortgage company threw it out as completely inappropriate.

Do not allow anyone who sells silicone injections near the house.

My first suspicion would be a leaking pipe under the floor, it matches the house age.

You can verify this, but, anyway, the floor will need to be dug up whatever the reason it is full of water. Preferably before you move in and start decorating.

Not a big job. Think how quickly roadmenders dig a hole with pneumatic drills.

The new floor will be better, laid with insulation and DPM and you can include UFH if you want

If it is the water supply pipe, run a new one out to the road, in 25mm or 32mm plastic, and that will give you much better flow as well, , suitable for an unvented cylinder or a big combi.

Thank you @PigletJohn. Reassuring to hear it’s not a big job to dig it up! I spoke on the phone to a damp surveyor and they said although they could survey it for me they wouldn’t be able to tell me if it’s the membrane or the leak themselves and it would need to be dug up anyway

I have a builder coming to quote on the other work after half term so will get a quote for that as well.

you can hear a leaking supply pipe with a stethoscope

older plumbers may use a glass of water at the kitchen tap

the new pipe need not follow the same path as the old one

if there are any lead pipes, ask the water co to test drinking water for lead content BEFORE starting work. there may be a subsidy or other help.

@PigletJohn than you this is so helpful! I’m so glad I posted now I don’t feel quite as stressed with some actual practical information now. How do you test with a glass of water? Is it something I could do do you think?

you could.

These people call it a syphonic cup test

you need an assistant.

I favour the stethoscope method.

but at that age, it's time you had a new water pipe, with improved flow, even if it isn't leaking yet