I have a ground floor flat, that is experiencing some damp issues and I am struggling to figure out how to solve or what could be causing them..

I rent the flat out, so can't monitor exactly what goes on all the time, but the tenants are very open and seem decent people, especially as they are 2 girls in a 1 bedroom flat

The flat experiences damp in a few places, in the under stairs cupboard, in the bathroom, in the wardrobe and in the hall.

In an attempt to rectify I have fitted a fan in the bathroom, ventilation to the understairs cupboard and requested that they keep doors and windows open when cooking, showering and drying clothes.

They have said that they never dry clothes in the flat, as they always take them to the launderette, they always keep doors open, they have some dehumidifers in the worst places and they open windows when cooking and showering.

The flat, being ground floor, has a concrete floor and very thing carpet and what feels like little on no underlay, it has normal central heating and is only 5 years old, so should have good insulation and a flat above, so no empty roof space.

Along with various spots of damp, my tenants have a bedframe that when the mattress sits on top it forms a sealed empty space, not sure how to explain it but imagine the 4 sides of the bed frame are about 12 inches high and form a constant square and when you put the mattress on top it seals and allows for no air movement. This is causing the matterss to get damp underneath. I think this is because their is no air flow, the floor gets so cold and causes damp underneath!

So do we have any damp experts here, what could be causing this issue, it is worst in the winter and wet months and largely disappears in the warmer months. I have a feeling that it could all stem from the concrete floor and maybe shoddy insulation in some of the walls.

Thanks, as always, y'all

Condensation, the cause of most damp issues. If you have eliminated other causes, such as leaky gutters, rubish piles against the walls, then condensation is your enemy.

Have similar issues in our house . One of the options is to keep the house/flat at a higher ambient temperature. This will prevent the dew point being reached. Then ventilation can work. It is a very tough issue to crack though

Yep, eliminated all that, we have no gutters as ground floor, but the gutters all flow where they should and don't leak, there is no rubbish or anything like that.

Problem with keeping the temp high, is as its not us living there, we can't make them do that, hence I went down the ventilation route.

Given the flat is 5 years old any residual moisture from the construction stage should have long dried out I would suggest there may be a problem with the damp proof membrane below the concrete floor. If you have NHBC warranty remaining or even if you don't you should contact the builders and have them test the floor moisture levels.

In your case insulating the concrete floor will help and if the walls are cavity then consider cavity wall insulation. There are still grants available too.

How old is the property?

We've tried the NHBC but they said if the house is falling down they'll pop over and have a look, otherwise tough titties.

We have had issues with the NHBC on other properties, they are great, but only if you suffer problems on a tuesday, in a month that has less than 6 letters in it, the temperature is less than 13 degrees when you ring them and your name has an even amount of vowels and consenants! They are very very difficult to pin down!

The letting agent is looking into getting a damp expert round to have a squizz and give some guidance!

Only about 5 years or so..

How do you insulate the floor?

You can get boards that go under laminate, then lay underlay and the carpet on top.

Beware "damp experts" , most will suggest rising damp and will give lots of expensive solutions to a non existent problem. It is hard to find the cause when you are living in the property, almost impossible if you aren't.

Don't newbuilds have a 10 year guarantee?

Is the damp coming from the bottom up?

It's possible that whoever done the boarding didn't lift the boards off the bottom to leave a gap, which is what you're supposed to do, therefore allowing damp from the floor to rise.

Also, if it's a floating concrete floor, check the air bricks aren't blocked.

Seriously sounds like insufficient ventilation or a bridging of any of the damp proof layers, I suspect lack of ventilation but don't have any experience with modern houses
You need to get some windows open long term but I imagine being a rented flat that May be difficult especially being on the ground floor!

Thanks BB, i'll get onto them.

That website looks good, ventilation is the secret most of the time

Almost certainly it's due to condensation from lack of ventilation. Either that or night time incontinence.

Heat recovery units can be effective, but as TurboVerde says don't come cheap. It would be interesting to know how much water the dehumidifiers are pulling out. That's if they're really being used that is. Same as the bathroom/kitchen fans which invariably get switched off under the perception this will save money.

Can't really help, but are the bathroom fans easy to install Jim? I'm thinking of putting one in our bathroom as the ceiling has a few patchy bits appearing.

Depends where the bathroom is. You need to feed it from the lighting circuit and it must have an isolating switch outside the room our a pull switch inside. Then just decide if you want to go through the wall or through the roof and use trunking.

Easy diy, if aces is ok. Makes a big difference too. Get a fan with a delay so it stays on after you have left the room.

Fan
One of these and a few of these and these
One of these , these and these
One of these and these

With some 4-core cable the above should do most homes with easy accessed loft space above and an outside wall nearby. You'll also need to hire, borrow or steal a core-cutting drill with clutch and a 100mm core-cutting diamond bit. Always use rigid ducting and never the flexible, corrugated stuff which creates turbulence and reduces efficiency.

We had a mould issue in our shower and since fitting the above and a towel radiator we've had no problems.

As Skins says above. I fitted an extractor when I refitted our damp, cold and mouldy bathroom, (in the furthest corner from the door so that it always draws the air across the entire room) and it has made a massive difference, as has the heated floor. Also got my stuff from TLC.

Ah thanks chaps. Does it have to vent to outside or can it just vent into the loft?

I would vent it outside, otherwise you could just be transferring the problem elsewhere.

Definitely outside.