problem with tanking slurry

[babyseat]

I tanked a room a month or 2 ago with cementone tanking slurry and now some damp seems to be coming through it. Originally there were some damp patches on the floor and also on a couple of walls so I tanked the room and the floor using SBR as a bonding agent, 2 thick coats at 90 degrees to each other. I had a look the other day and there seems to be a couple of damp patches on the floor which seems to match up with the problem areas from before. The same patches also line up with the insulated radiator pipes which are running through the exsisting screed, but there didn't seem to be any problem with them and they shouldn't be leaking, and even if they are it shouldn't be coming through.

A floating floor had been laid on top of it, and it was when that was taken up for another reason that the patches were noticed, they are not soaked and dry up withing half an hour of contact with the air, but im sure this isn't right. does anyone have any ideas what could be causing this??

thanks

 

[Blagard]

Condensation is one possibility.

Did you have the heating on when you applied it? - The pipes in the screed may affect the curing process if they were warm at the time. If not applied strictly as directed then you may get issues.

 

[babyseat]

Cheers for the reply, heating was disconnected at the time, radiators off so definitely not hot, I had thought abut condensation but it seemed like a strange place to get it without showing anything on the wall. All applied following directions on bag, mix ratios and 2 coats at 90 degrees to each other.

I spoke with the technical dept at cementone today and they told me that while it is waterproof it is not water vapour proof, was trying to get more information out of him but I think he was just reading of a screen as he kept repeating this over and over again whatever I asked him!

Not sure what this means, if water is getting in as water vapour how can it be sold as a tanking slurry? And what can I do about it? The wet patches are on the floor, and are not that bad, but there is a floating hardwood floor on top which means that there is no airflow to dry it out, so eventually I guess there could be enough water to cause a problem?

Any ides would be very much appreciated!

thanks

 

[Blagard]

For Water vapour read Gas - That can pass through things that Water in liquid form cannot. That is why we have vapour barriers in building construction to stop the moisture in the air getting where we don't want it and breather membranes where we want it to pass

 

[babyseat]

So do you reckon there is anything that can be done without re doeing the whole thing. Its an old house with no dpm, cavity etc, and they were aware that tanking a room is not the perfect solution as water might appear in other places etc, but we didn't expect it to come through the tanking. Do you think going over with synthaprufe or something like that would be a reasonable solution?

 

[Blagard]

I am not sure you have grasped the problems with basements fully.

Your tanking slurry may well be doing its job with regard water ingress, but no matter how waterproof the basement is you can still get condensation if the surfaces (walls and floors) are cool enough and they frequently are in basements

You may well be heating the room fine but one of the biggest problem in those situations is ventilation - to move the moist air out of it and to get fresh drier air in.

 

[babyseat]

its not a basement, its a front room. It has a wood burning stove in it and a vent for the stove, so heating and ventilation shouldn't be a problem. I don't think its condensation because of where it is, i.e. the floor underneath the floating floor but not on the walls. It does appear as if its getting through the tanking, which makes tanking it in the first place seem a bit futile.

Like I said before, if the amount of water is not a lot, once the floating floor is lifted up, it dries in about 20 mins, but if its coming in under the wood floor and doesn't have any air getting to it, eventually I think it could lead to a problem, that's why I was thinking of synthprufing the floor, what do you reckon??

 

[honnymoo]

Hi babyseat we have a similar issue by the sounds of it.We live in a Victorian terraced house with solid brick party wall (not cavity wall). The houses on our road are on a slight slope, making our side party wall about a foot lower than our neighbours. As a result we have had issues of damp as moisture from the foundations of our neighbours house has come into our home. We have just stripped the affected plaster to the brick, repointed faulty mortar and have applied sbr and a cementious tanking slurry to wall. However where we are below the neighbours house level the tanking does not appear to be fully drying (ie the moisture from under the neighbors house appears to have stopped the drying process for our tanking). Should we continue to apply sand/cement layer and go on to replaster, or will the dampness from their foundations continue to come through? Is there anything we can do to stop this issue or will we always have moisture spoiling our plaster work/decoration? Any help/advice gratefully received!