Want to install wooden floors but have penetrating damp Help

[Lottielou_77]

I need some advice regarding damp floors in our house - terrace c1870. The living room currently has a solid stone slab floor with a red coating over, and is very uneven. It seems it has a damp problem though. The previous owners had covered it with a carpet but when we took this up the underlay was soaking in some areas. This dried out after a few days/weeks.

My question is how we deal with this. We have been advised by a friend to lay a breathable floor but I'm not really sure what this entails. We had hoped to install a wooden floor but I am concerned this will rot if the floor is wet. I'm really confused by the whole situation! Are there any damp proofing options? I am concerned that putting a membrane down may drive the damp into the walls. We also have a problem with condensation and mold on the external wall so I'm not sure if this is something to consider too.

We also have the same stone slabs in the kitchen. I am happy leaving the slabs exposed here but I dont understand how the floor can be 'breathable' when the furniture is stood on it. Won't it get wet where cupboards stand and damage them? The skirting has already rotted. The gable wall is also suffering from penetrating damp as it is below ground level. Again I am wondering what the best option would be to deal with damp here.

Any advice would be greatly appreciated. Thank you.

 

[Gareth Hughes]

This sounds like a familiar problem that I'm sure has been covered here before. Since new user's posts take a while to appear I'm just bumping this up so that someone can point you in the direction of some of those earlier discussions which should help explain everything.

 

[Lottielou_77]

Thank you! I tried having a look for similar topics but had no luck so if anyone can point me in the right direction I would be really grateful.

 

[Keithj]

I'm no expert, but I've been there - done that.

Damp-proof materials, on the whole, just drive the wet somewhere else, sometimes with worse results than the original problem.

The first essential is to find out where the water is coming from. That can be surprisingly difficult, but sometimes you get lucky. Until you know that, any attempts to fix the problem will be random and may achieve nothing (except making a tradesman richer).

Water has the ability to wander, so where the wet appears may be a long way from where it's getting in - as I found when I kept repairing daughter's bedroom ceiling years ago. The "leak" was in a roof valley the other side of the house, and running down a diagonal timber to the lowest point.

There are folks on here who have dealt with major floor-level damp problems and solved them. I've done walls aplenty; won most, waiting to see if I've won with the last one.

My house floor inside is below ground level outside. There's a French drain outside (now) that goes well below indoor floor level, and that problem has gone away. The other problems were to do with rain not going where rain should.

 

[MatthewC]

Hi LottiLou, welcome

Firstly, it sounds as though you are on the right lines - have confidence that what you say above IS the right way to do things. Secondly, most things to do with getting rid of dampness are going to take a while so be patient!

I assume that the gable is beside the kitchen? Are there any other sources of water to your living room? The ground level outside your gable wall sounds like a major part of the problem and could even be the whole problem. (A photo would be nice!) Dampness will get into the house and under the floor from there very easily. I would investigate how difficult it would be to get the outside ground level 6" BELOW the floor level. I did this (see my blog by clicking the blue spot on the right) and it has worked as advertised - last winter we never had any dampness at all.

To answer your other questions:
1. A solid breathable floor is made of limecrete plus some other clever aggregate - you have to dig out about 400mm and build it up - I did one (see blog again) and it works.
2. A wooden floor will indeed rot in damp conditions, and you would need to make it a suspended wooden floor by digging out, supporting the floor joists on pillars or walls, and ventilating the space underneath the floor - but even then you need to know why the ground is wet
3. In the traditional sense, there are no damp proofing options and yes, a membrane will drive the damp into the walls. In my view, old houses were built to different principles (with breathable lime) to modern ones which are a sealed cement box, and the different techniques just don't mix well.
4. Your problem with condensation and mould on the external wall is possibly the same as 2 and 3 above - not enough ventilation - but check outside for leaking gutters or downpipes as well.
5. Re your stone slabs in the kitchen, it's a matter of terminology - a breathable floor is just that, it's not actually wet, it just breathes to allow the passage of water vapour, so furniture stood on it won't get wet as such - but it is good practice to make sure that spaces behind cupboards etc are ventilated.

Hope this helps

Matthew

PS Where are you?

 

[Lottielou_77]

Hi. Thank you for the replies.

Unfortunately the gable wall (the main kitchen wall) is below ground level to waist height but the land outside is our neighbours garden so we have no access to the side of the house so I'm not sure we can do much about it :?

I don't think there are any other sources of water in the lounge. All the radiator pipes etc all run above the floor so I am confident there are no leaks. Half of the lounge is above the cellar though which is very damp so I'm not sure if that has a role to play.

Thanks for confirming my doubts regarding a damp proof membrane...its so hard to find a contractor who agrees with this! If we were to fit a 'breathable floor' with the limecrete as you describe what options are there for finishes besides the suspended wood as I'm not sure we can afford this option?

In terms of the mould on the external wall, ventilation in the house isn't great. We have an indoor cat so haven't found a safe way to open the windows we have and the windows in the lounge only open into the conservatory and not outside (its a quirky house). The walls are always really cold too even with the fortune we spend on heating! I don't think there are any outside leaks, and this wall is part of a tunnel/passageway running between our house and the neighbours with a bedroom over the top.

Just going back to the stone slabs in the kitchen. I think there must also be (the same?) damp problem there then as where we have placed a small rubber backed scratching mat for the cat, there is a wet patch underneath and mould had formed on the bottom of the mat. I haven't noticed any other obvious wet patches, although it does look suspiciously dark under the fridge.

The frustrating thing is when we bought the house the home buyer's survey said there were no damp problems that needed dealing with, but covered themselves by saying we should get a damp survey anyway.

Thanks again for everyone's help! Really appreciate advice from people sympathetic to old buildings! Despite its problems I still feel like it's the most amazing home I could even dream of living in!

Charlotte

P.S we are in West Yorkshire near Bradford

 

[MatthewC]

Hi Charlotte

Well, the gable wall undoubtedly causes the dampness in the kitchen floor. The moisture in the floor is evaporating into the kitchen and anything impermeable on top (which includes most modern mats and rugs!) will prevent evaporation, hence the wet patch. One option (with your neighbour's permission) is to fit a French drain outside (search the forum for details) which would be a bit of work but would help the problem.

My kitchen floor (see blog) is limecrete covered with limestone slabs, so yes, it wasn't cheap but it is exactly what the house needed. You can cover limecrete with anything natural, breathable, unsealed and definitely NOT ceramic!

You are going to need to sort the ventilation problem - old houses need to breathe. The reason why the walls are always cold is that they still contain moisture; every kJ of expensive energy spent heating the air is actually trying to warm the walls. The trouble is if the wall is damp than you have to use lots of energy just to convert that water into water vapour due to the latent heat of vapourization (which is the amount of heat needed to do that conversion without increasing the temperature of the water). If you still have a source of water inflow into the walls (roof? flashing? gutters? downpipes?) then you will carry on forever using heaters without heating the air! Effectively the dampness is sucking your heat out of the air so it never warms up. On my house it took months to dry the walls after sorting the roof etc. Another problem could be that you have lots of cement rendering, gypsum plaster, other modern solutions etc???

Matthew