Flagstone flooring - moisture

[luckyt1982]

Hello

We have recently moved into a 1850 ish property. There is flagstone floor in the living room, following into the kitchen.

We are aware of damp (been diagnosed as rising damp by one specialist company, but I'm going to get a second opinion after reading the rising damp myths!) in the kitchen. There are areas where the plaster is blown and having scrapped off the bubbling paint and plaster, it looks damp.

We have also noticed moisture coming through the grout in the flagstone flooring, mostly confined to the areas near the 'rising damp' in the walls, but also a few other areas. The floor is quite worn in the kitchen area and the 'grout' is perished. We can see a plastic sheet coming through in one corner of the kitchen, which I assume is a DPM.

My question is - is it 'normal' for moisture to come through flagstone flooring and its grout? If not, is there any treatment that can be done without ripping up the floor and replacing the DPM?

It might be that the 'rising damp' in the walls is finding it's way into the floor - so the issue might be solved when we have this sorted.

Thanks

 

[AMc]

Welcome to the forum!

The problems in the walls may well be the result of other problems but a dpm underneath the flagstones is likely to be pushing moisture towards the walls (as it can't escape under the floor).

"Treatment" for damp usually involves trying to seal one surface to prevent moisture moving through it, as you've discovered this causes it to find another way out - the thing you need to provide is breathability a.k.a. vapour permeability.

Don't rush to inject/tank/render as this is likely to be ineffective, expensive and destructive to your old house.

Start with obvious things, are there any leaks in the guttering or other pipework that are soaking the walls? Are the ground levels outside higher than inside? Has the outside of the wall been rendered? In cement? has it cracked?

Cunningly hidden in the dormat hot topics forum you may find this is useful reading...
http://www.periodproperty.co.uk/forum/viewtopic.php?f=6&t=6777

 

[Andrew Bodenham]

luckyt1982,

Welcome. Congratulations on your new house.

I'll echo AMc's comments about not rushing into anything. The house has been up for 150+ years, so it can't be that bad.

There are many causes of 'damp', and I urge you to read as much as possible, here and elsewhere. If the house has been unoccupied for a while then the situation may improve with ventilation - that was our experience. Meanwhile look for likely causes of ingress, and consider lifting a couple of flags to see what they are laid on - a small trial pit will reveal the prescence of a dpc for example, certainly give you some more clues to work on.

Let us know how you get on!

 

[plasticpigeon]

Hello

I'm afraid i don't have a great deal of experience with solving this sort of problem. Personally i wouldn't have thought it usual to have damp coming through the grout or flags on the floor if there is a damp proof membrane, it is supposed to stop that!!!!! However it seems logical that the damp proof membrane will stop evaporation from the floor so making the ground below it wetter, and potentially making the bottom of the walls wetter. I guess this could be a driver for rising damp (although whether it really exists seems still up for debate).

People on this forum have had success in keeping solid floors dry even without a damp proof membrane by taking logical steps as outlined by Amc and Andrew. Other things to look out for are that the pointing on the wall is in good shape especially at the base of the wall where water can splash against it, and also check not just your ground levels but also that the ground slopes away from the house, otherwise water will run towards the base of the walls. Do you know where your water supply pipe runs, and is it lead or plastic??? I think it less likely to be the pipe, but a friends water supply pipe failed in his garden due to tree root damage so not impossible.

Whatever the reason I'm sure there is a logical explanation so if you were thinking of going down the injection and replastering route, perhaps hold off a bit, a simpler solution may present itself.

 

[luckyt1982]

Thanks for your replies!

I think we will do some more investigation this week, including a visit to the neighbours to see what's on the other side of the walls that are getting damp. I think it's their garden, so hopefully they haven't started a compost heap or something similar up against that wall!

I have a feeling that the ground levels outside are slightly higher than inside, but will check this out. What happens if this is the case? What are the suggested remedies?

 

[luckyt1982]

Thanks for your replies!

I think we will do some more investigation over the weekend. Including going over to our neighbours to find out what's the other side of one of the walls that's getting damp. Hopefully they haven't started a compost heap or something similar up against the wall.

What happens if the inside floor is lower than the floor ourside? Are there any suggest remedies to control damp?

 

[MatthewC]

Hi lucky1982

I agree with all the above and would add that I bet the flags were sealed if they put a dpm underneath them, hence any dampness above the dpm (even spillages) will probably come up through the grout. Also, if your blown plaster is above skirting board height, I would guess that the "plaster" below is actually cement. However, my money would be on earth and/or concreted ground touching the external wall at (or even above!) the floor level inside. If you have this then my priority would be to fix it at once, even just temporarily by digging a trench beside the wall.

The best single piece of advice I got from this forum before I started was to do nothing permanent in a hurry unless you are positive it is essential like a new roof and gutters etc ... Then let the place try to dry out with you living in it and then reassess the priorities.

Let us know how you get on, and give us some photos when you have time, please.

Matthew

Edit - I really do get annoyed by the delay in publishing the posts of new members, as the above posts were not there when I wrote this one!

 

[JoceAndChris]

Reading through your post carefully, luckyt1982, I wonder if you are describing 2 kinds of damp problems. One is that the flagstones are laid on plastic, and this is pushing moisture into the walls. I agree with the advice to lift a flag very carefully and see what's going on. I don't think they should be laid on plastic, mine are laid on earth and give me no trouble.

The other problem is that you're seeing moisture "coming through" the flags. This I'm more skeptical about, how do you know it's coming through? Isn't is more likely to be the warm air beading, even pooling, on the cold flags? A lot of us are suffering with this kind of condensation at the moment with all the hot humid weather.

Both problems will be remedied by increased ventilation, and decreased moisture production - which might be a leak or might just be drying laundry, breathing etc!

And a big welcome to the forum.

 

[robgil]

A specialist will cure the effects of damp , you really need to find the cause.