Jump to content

Damp understairs cupboard


jayc89
 Share

Recommended Posts

We have an approx 3 x 1m understairs cupboard. The floor tiles are laid direct to soil so are always damp. The walls look like they were at one time covered in some sort of tanking that's just flaking away now (beneath a sort of pebble dash coating it's incredibly chalky).

 

To the left is our kitchen, the right is the staircase and hallway, directly in front is a brick wall and beyond that a ventilated void beneath a beam and block floor.

 

I've thought about cutting a couple of bricks out of that wall and fitting air bricks to allow for some circulation which should help (keeping the cupboard door open has reduced the humid feeling down there) but it's not really an ideal solution as we're just encouraging a draft. Whilst we'll never achieve modern airtightness standards, I would like to avoid making it any worse.

 

Ideally I'd dig out the existing tiles and relay the floor, incorporating some sort of DPM. The main concern is, with the property being 150 years old, we don't have a DPC for that to lap over so by doing so will I just move the moisture elsewhere? Given it's next to our staircase I don't particularly want to encourage the moisture up towards that.

Any ideas/suggestions would be greatly appreciated.

 

IMG_5725.thumb.jpg.b5385196699459cf4b785d2b22c1bc1b.jpg

Link to comment
Share on other sites

Limecrete floor, limewash or lime render the walls, linseed oil the floor limewash with egg whites in it for the walls. Damp should move down not up unless the water table is very high. 

Link to comment
Share on other sites

Not a bad solution or you could have a go with Sika tanking render / slurry.

 

If the rest of the house is on beams can you drop the level in the cupboard below the beam level - not a great thought having damp around timber beams although they seem to have got used to it if the house is 100+ years old!

Link to comment
Share on other sites

1 hour ago, tonyshouse said:

Limecrete floor, limewash or lime render the walls, linseed oil the floor limewash with egg whites in it for the walls. Damp should move down not up unless the water table is very high. 

is it not too late given all the gypsum product that appears in the picture?

Edited by Ajn
Link to comment
Share on other sites

Limecrete's a good call. I suspect 80mm of the finer grained foam glass would be suitable for such a small area, finished with 50mm of lime screed? I'd want to try limit the build up and/or how much I have to excavate as it'll be a faff getting material in/out of there.

1 hour ago, Ajn said:

is it not too late given all the gypsum product that appears in the picture?

If I was to go the lime route, I'd expect to knock all the old render off first. I did this in the section beyond the wall in this pic, so I know it's stuck on pretty well :)

Link to comment
Share on other sites

I suspect that that moisture is being pushed up due to the fact it's below external ground level ( correct me if I'm wrong but I seem to remember steps below your stairs leading down? )

 

Either way I would do absolutly nothing to trap moisture there for the time being, including laying any kind of floor on top. Water has a way of appearing one way or the other. At the moment I think it may be acting as a drying sump for the soil beneath your house. 

Link to comment
Share on other sites

Posted (edited)
9 hours ago, Iceverge said:

I suspect that that moisture is being pushed up due to the fact it's below external ground level ( correct me if I'm wrong but I seem to remember steps below your stairs leading down? )

 

Either way I would do absolutly nothing to trap moisture there for the time being, including laying any kind of floor on top. Water has a way of appearing one way or the other. At the moment I think it may be acting as a drying sump for the soil beneath your house. 

 

That's right, where the wall steps out is ground level. It's probably 0.5m below ground level at its lowest. Other than in the hight of summer the floor's never dry there. 

Would you avoid even breathable floors inc. Limecrete? If so, why?

Edited by jayc89
Link to comment
Share on other sites

Any increase to the floor's permeability will push more moisture up through the structure. Limecrete is more vapour open than Concrete but nowhere as near as much as soil. It is not a solve all solution. I certainly I wouldn't put it over damp soil and expect the permeability change not to cause any issues elsewhere. Instead of a damp floor, you'll get damp walls. 

 

A table from the below shows my thinking .

 

 

https://purehost.bath.ac.uk/ws/portalfiles/portal/203983214/Phillips_et_al_2019.pdf 

image.png.14965d6da0c1697ec52d7e180ce5345e.png

 

 

I think a french drain dug around the perimeter of the house well below the level of the floor in the cupboard and always drained to a lower plain would solve the issue. Alternatively just put 100mm of gravel in the floor or make some kind of slatted base to keep your goods dry and leave the floor alone.  You'll still need to remove the moisture through heat and ventilation. 

 

 

The elephant in the room here is of course the house design being tweaked and bent around a vintage staircase and now a damp 3m2 cupboard. I would fill in the cupboard, and knock the stairs, add some EPS and limecrete over. Expecting a sunken room, often below the (localised) water table in an old house made from nice permeable materials to ever be dry is optimistic at best. 

 

 

 

 

 

 

Link to comment
Share on other sites

The house has certainly been tweaked although the cellar was always damp, which was a driving force in decided to block and beam over it.

 

There’s certainly heat in the area, the cupboard you can see to the right houses are UFH manifold. It’s ventilation that’s currently lacking. Even with the cupboard door constantly open, it helps a bit, but it’s no where near drying it out fully. 
 

A French drain has been a consideration for a while now, although this section of the house is pretty much dead central so I’m not sure how useful a French drain around the perimeter would be for this situation.

Link to comment
Share on other sites

Only two choices where the damp is coming from, 

 

Condensation from when moist internal air meets a cold surface or

 

Water infiltration.  If there's heat in there already I'd wager it's the latter. Have you thought about making a model ?

 

Fill a large dish full of your local soil, compact it, dig a "cellar" in the middle and pour some water around the edges to see if it replicates the behaviour of your real house, with the slow influx of damp. 

Edited by Iceverge
  • Like 1
Link to comment
Share on other sites

  • 2 months later...

Just to close the loop here - I spoke with Ty-Mawr about my damp cupboard. They recommend limecrete with a foam glass/Glapor sub-base as apparently that will prevent any moisture wicking up without introducing the side effects associated with a physical DPM.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...