Damp walls

[Alcazar]

OK, all those of you who've lived out in France in older properties for some time, share your knowledge please.

Our property has NO dpc, and is built of stone, with crepi on the front.

Inner walls are mostly plastered.

The problem is that within about a metre of floor level, the plaster is very powdery, won't take paint, and any wallpaper is just coming off.  Even internal walls are affected. Above that, and upstairs, no problem.

So...........I surmise rising damp, but what do I do? Is there a recognised product? Or are we into removing all the plaster, cleaning up the stonework, and redoing the chou?

TIA for any advice.

Alcazar

[GRT17]

This sounds very familiar! We too have an old stone built house but without the crepi on the outside.

We have the same problems. We have overcome it in our kitchen by using a fibreglass wall paper which is glued to the walls with a special, very strong glue, never to be removed I believe! As our tiler explained, this stuff quite literally holds the walls together. Once the paper is on the walls then it is painted with an emulsion type paint. Useful, as it is easy to paint over any scuffs or marks.

All products are available from M. Bricolage, the paper comes in a variety of textured designs.

Bonne chance

Gill

[Alcazar]

Come on guys, I refuse to believe that NO-ONE else on the forum has ever had damp stone walls, and that NO-ONE knows alternatives to deal with it.

Please help.

Alcazar

[I1]

My (limited) experience (my own property) and from what others have said is that damp is less of an issue in France than in the UK. That is not to say there is less but that people make less of an issue about it.

I think a lot of other French properties were “designed” to breath (i.e. that water taken up though the walls would just evaporate away without problems (both internally and externally). Which is fine until people start to render the outside (impermeable) and use impermeable finishes internally.

I have no experience of the powdery layer that is causing you problems but would recommend that whatever you do apply is permeable to water (to allow the property to breath). When I purchased my house the surveyor commented that he was not very much in favour of injected DPCs and that they are not appropriate to all properties.

It would be difficult for even somebody who knew what they were talking about (i.e. not me) to comment on your specific property. You can get injected DPCs in France (look in Yellow Pages) and I’m sure that, just as in the UK, if you got one of those companies round they would want to start injecting.

In my property I accept that its nature will mean that there will always be some water in the walls (it’s a watermill). What I am doing is panelling the bottom 1m of some of the walls, with a decent air gap between the panelling and wall and putting in vents. The idea is that any wall “problems” will be hidden, but the wall can still breath and the water can still evaporate. It is what others suggested, though it’s too early to say it works of as “side-effects. I am actually using a large air gap (6 ins) so I have a shelf on top, though I was told one needs less than this (one person mentioned 25mm air gap) I also have quite large rooms so “shrinking bit a little is not a problem for me.

You might find http://www.oldhouse.info/ohdamp.htm interesting (sorry, you will have to cut and paste this like as I still cannot use formatting in my messages).

[Musicmonkey<ADDRESS><STRONG>Musicmonkey<STRONG><ADDRESS>]

We have suffered from damp though ours is supposed to be caused by condensation.  There is a product called Dépron, a sheet of polystyrene.  this comes in very thin sheets. We have had this glued over with a kind of fibreglass glue to strengthen it.  We have papered over this.  With increased ventilation, the problem is much improved though not completely solved.  However, we are not keeping constant temperatures as we use our house as a holiday home (also rented out).

 

[Alcazar]

Thanks to both for replies. Yours, Musicmonkey, sounds very much like my first reply, above.

As for panels with an air gap? Yes I can see this working. Does it need the top to be pierced for ventilation, or is ventilation built in somewhere else? A bit like radaitor covers in the UK?

Did you make your own panels? If so, of what?

I can see my wife liking that idea, especially if she can have T&G wooden panels, but what about the VERY irregular walls in old properties?

Does the rear of the panelling need some sort of treatment to avoid mould? And waht of vermin behind them.........a definite consideration where my wife is concerned.

Thanks again,

Alcazar

[Iceni]

Alcazar

Luckily our stone barn shows no sign of damp, there is no crepi/plaster inside or out so maybe that is why. I am guessing that in yr case the lack of dpc allows water to be drawn up into the walls and the crepi etc prevent natural evaporation. Is removing the crepi/plaster on one side or the other an option ? All the advice that we have had is to leave the stone uncluttered.

BTW Di will not allow me to comment on yr juxtaposition of the words vermin and wife in yr last sentence.

John

not

[I1]

In my responses below, please remember that I am an ungifted amateur not a professional builder (so if anybody knows the correct thing please, I wont be offended if you tell me I’m wrong). My suggestions below are not “what you should do”, but rather “what I have done”.

>>Does it need the top to be pierced for ventilation, or is ventilation built in somewhere else? A bit like radaitor covers in the UK?

I’ve left the top solid (generally 150x25mm timber). I’ve cut holes in the face of the panelling and fitted vents. I’ve actually painted my panelling and the vents match the paint colour so hardly show. I’ve subsequently found some quite neat long narrow vents that would fit nicely in the skirting.

When I get to the walls with radiators on I’ll be taking the radiators off, building the panelling and then fitting the radiators to the new front of the panelling (i.e. not building the panelling round/enclosing the radiators).

>> Did you make your own panels? If so, of what?

I build a frame out of something line 60x40mm timber (framing screws into the wall – bit like a mini stud wall with smaller timber). I use the T&G panelling you can get a virtually ant DIY store (Lambris). I’m actually using 7mm thick stuff that is not particularly wide. Its all pretty cheap. I’ve fitted my panelling vertically

Top (150x25’ish - though not a constant 150 after cutting to wall shape and you could probably make it a lot narrower). My is 1m high. Frame has three horizontal 60x40 batten, top, middle and bottom (for skirting). Top overhangs the panelling (sticks into the room approx 1cm from the room face of the panelling) and I routed a grove under the front (bottom) edge of the top so the top of panelling fits into the top (this helped a neat finish as you don’t see where the panelling)

>> “what about the VERY irregular walls in old properties?”

The panelling is away from the wall and thus not affected by uneven walls. After the top frame batten (60x40) was fixed to the wall, the top can be offered up and marked/cut to fit the uneven wall exactly.

>> “Does the rear of the panelling need some sort of treatment to avoid mould?”

I primed the back of the panelling (microporus paint). After building the frame I actually covered the frame with plastic sheet (to protect the wood from what would become a higher humidity area between wood and wall (holes in plastic sheet to allow vents to actually ventilate the gap). However, I was subsequently told that the plastic sheet was probably not a good idea. My reason for it was that is the humidity kept changing in the gap then the wood would move and end-up splitting.

>>“And waht of vermin behind them”

I tried to make sure there is no way in for vermin. However, if they can get in, they can use the same method to get out so I recon its not a problem.

If people think I’m getting it wrong, please say – I’m no builder (I’m also no good at explaining things to I hope some of the above makes some sense).

[zeb]

Before we moved in permanently we shut and locked shutters but left windows open slightly and internal doors open while we were in the UK. That solved the condensation problem so that we would arrive to a well aired house with no damp.

Since moving here we've had no problems at all - I presume because we have central heating and VMC. Cottage is old - dressed stone with render/crepi on side walls.

[Dave&Olive]

has anyone tried this

http://www.safeguardchem.com/Damp/risingdmp.htm

dave

[Musicmonkey<ADDRESS><STRONG>Musicmonkey<STRONG><ADDRESS>]

Dave,

Thanks for posting that link.  I found their item on condensation very interesting and reassuringly we have taken most of the steps they suggest.  The only trouble is, they suggest getting rid of the black mould (potentially harmful to health) with bleach or a special paint and I doubt my wallpaper would survive that!  Any other suggestions would be appreciated.

 

[Dave&Olive]

hi

       just had this back .........it might not solve what we thought

http://www.screwfix.com/talk/thread.jspa?threadID=14786&tstart=0

        dave

[Wilko]

Many old houses in the Uk are built from clunge, as is mine in Provence. This a mixture of stone, mud, lime and anything else that came to hand. The advantages of this type of construction were low cost, most materials on site, and thermal efficiency ie cool in summer and effectively well insulated in winter. One of the drawbacks of wholly stone houses is that they are not so thermally efficient especially in winter.

However many stone houses were constructed using a shuttering method ie the middle third was often made from lime, mud and rubble. As one previous reply mentioned it is essential the the middle of the wall draws dampness from the earth as this provides the "glue" for the wall. There is a celebrated example in the UK of a couple who installed a chemical DPC in their clunge walls only to find that the building became unstable after a few years because the walls had dried out.

The traditional method of cutting rising damp, yet maintaining the walls strength, is to install a french drain around the property.

I would avoid the use of chemicals and modern solutions, because the house must breathe, ie don't use cement but lime. Your local building merchant will be able to point you in the right direction.

I hope that this is of help and remember your property has been there for several hundred years and traditional solutions will work far better than modern ones.

Bon courage Wilko

[Pushkin]

[quote]We have suffered from damp though ours is supposed to be caused by condensation. There is a product called Dépron, a sheet of polystyrene. this comes in very thin sheets. We have had this glued over...[/quote]

This advice was given to me on another forum by someone who seems to know what he is talking about:

'And as for the polystyrene - do not under any circumstance put it under wallpaper. If you are unfortunate to have a house fire the polystyrene has the effect of putting an air gap under the paper which results in an instant inferno with added toxic fumes. It was banned in the UK years ago - I'm surprised its still around'.

Every wall in our house is covered with the stuff and I won't be happy until every last bit is removed.

Sue

[Tarn]

I go along with Zeb. When we purchased our house (used for holidays) the wallpaper was black up to about three feet from the floor.  Also is smelt of damp - badly. There was a distinct tide mark on the walls. We stripped it and pulled off loads of plaster (mostly it fell off). Luckily we described our 'rising damp' to a good friend of ours, a buildings surveyor, seeking his advice (on damp proofing). He told us it sounded like condensation and that that we needed was good ventilation. He advised against any form of DPC in a stone house of its age (late 1800s). We took his advice. We cleared all the air vents, and when we weren't there we left all the internal doors open and , left the upstairs windows open slightly, with the shutters closed. The house was very cold in the winter when we arrived but the damp improved as did the smell. A year later both were gone and we repainted.

I would advise caution against taking radical action like chemical damp proofing. Bear in mind that many of these houses have been standing quite happily for hundreds of years. They generally need a bit of understanding and treating properly. Work with them not against them.

John

[Musicmonkey<ADDRESS><STRONG>Musicmonkey<STRONG><ADDRESS>]

<'And as for the polystyrene - do not under any circumstance put it under wallpaper. If you are unfortunate to have a house fire the polystyrene has the effect of putting an air gap under the paper which results in an instant inferno with added toxic fumes. It was banned in the UK years ago - I'm surprised its still around'.>

Oh no!  We already have flock wallpaper upstairs which is another potential toxic risk and also very difficult to remove.  Now you have made me feel really safe (not).  Just when I thought we had got it sorted!