Damp proofing floor-level timber in situ

[orion.osiris]

Hi all,

I've been driven nuts trying to trace the source of damp which bridges thre= e adjoining rooms. Anyway, to cut a long story short, it seems that some br= ight spark built a dividing wall using a 4x2 timber framework faced with pl= asterboard between two of these rooms. This was plonked down on top of quar= ry tiles, which appear perfectly dry on the face of it, but which, it seems= , are acting as a conductive layer for ground water to be drawn up by the b= ottom length of timber which was plonked down on top of them with no DPC un= der it.=20 Given the impractability of jacking up the wooden frame a smidgin and sneak= ing a layer of DPC under the bottom timber, can anyone suggest a damp proof= ing technique that could be applied to this timber where it meets the floor= which would prevent it drawing water up from the ground? Is there some che= mical that could be sprayed on it or injected into it that would render it = water-impermeable?

Thanks.

[harry]

ree adjoining rooms. Anyway, to cut a long story short, it seems that some = bright spark built a dividing wall using a 4x2 timber framework faced with = plasterboard between two of these rooms. This was plonked down on top of qu= arry tiles, which appear perfectly dry on the face of it, but which, it see= ms, are acting as a conductive layer for ground water to be drawn up by the= bottom length of timber which was plonked down on top of them with no DPC = under it.

aking a layer of DPC under the bottom timber, can anyone suggest a damp pro= ofing technique that could be applied to this timber where it meets the flo= or which would prevent it drawing water up from the ground? Is there some c= hemical that could be sprayed on it or injected into it that would render i= t water-impermeable?

You don;t say how this problem is manifesting itself. If they are proper quarry tiles, they form a good damp barrier in themselves.

Are you sure this is not a condensation issue? Or even a water leaking from pipework etc issue?

[stuart noble]

[orion.osiris]

three adjoining rooms. Anyway, to cut a long story short, it seems that som= e bright spark built a dividing wall using a 4x2 timber framework faced wit= h plasterboard between two of these rooms. This was plonked down on top of = quarry tiles, which appear perfectly dry on the face of it, but which, it s= eems, are acting as a conductive layer for ground water to be drawn up by t= he bottom length of timber which was plonked down on top of them with no DP= C under it.

neaking a layer of DPC under the bottom timber, can anyone suggest a damp p= roofing technique that could be applied to this timber where it meets the f= loor which would prevent it drawing water up from the ground? Is there some= chemical that could be sprayed on it or injected into it that would render= it water-impermeable?

100% certain. I've spent several weeks part-time eliminating those possibil= ities. There WERE some leaks; they've now ALL been sorted and the thing sti= ll won't dry out completely. There's no condensation issue either. I'm wondering if the bloke who plonked the frame down might have screwed it= down through the quarry tiles, breaching any DPC there may be underneath t= hem. I've read that quarry tiles are naturally a bit permeable at the best of ti= mes and that this permeability is not generally an issue until you block ev= aporation from them - as is happening here by the construction of the divid= ing wall.

[Tim Lamb]

I don't suppose your good lady is swabbing down the tiles with a wet mop?

[orion.osiris]

Another suggestion I can 100% rule out. The dog's not pissing in there, either.

[Fredxx]

adjoining rooms. Anyway, to cut a long story short, it seems that some bright spark built a dividing wall using a 4x2 timber framework faced with plasterboard between two of these rooms. This was plonked down on top of quarry tiles, which appear perfectly dry on the face of it, but which, it seems, are acting as a conductive layer for ground water to be drawn up by the bottom length of timber which was plonked down on top of them with no DPC under it.

sneaking a layer of DPC under the bottom timber, can anyone suggest a damp proofing technique that could be applied to this timber where it meets the floor which would prevent it drawing water up from the ground? Is there some chemical that could be sprayed on it or injected into it that would render it water-impermeable?

That's not my experience of seeing lino almost floating on quarry tiles.

OK, perhaps not floating but still very wet. The pointing between tiles may also have contributed to the water.

[orion.osiris]

three adjoining rooms. Anyway, to cut a long story short, it seems that so= me bright spark built a dividing wall using a 4x2 timber framework faced wi= th plasterboard between two of these rooms. This was plonked down on top of= quarry tiles, which appear perfectly dry on the face of it, but which, it = seems, are acting as a conductive layer for ground water to be drawn up by = the bottom length of timber which was plonked down on top of them with no D= PC under it.

sneaking a layer of DPC under the bottom timber, can anyone suggest a damp = proofing technique that could be applied to this timber where it meets the = floor which would prevent it drawing water up from the ground? Is there som= e chemical that could be sprayed on it or injected into it that would rende= r it water-impermeable?

Thank you, Fred! I was beginning to think no one believed me.

[harryagain]

How old is the house and what is under the tiles?

Modern houses typically have 4" concrete and a damp proof membrane under that. Hence not like to be pierced and not matter if it was. That is why damp penetration is hard to understand. Rising damp is by capilliary atttraction.

Is the floor level above or below the outside ground level?

For water to get through quarry tiles, it would likely not be a simple rising damp issue but rising ground water/positive water pressure/ a spring. Far harder to deal with.

[orion.osiris]

Harryagain:

The part that's getting damp is comfortably above the outside ground level.= This part of the house was built in the late 1950s. I don't know what's un= der the tiles, but since I'm situated in an historically VERY wet part of t= he country I'm guessing damp proofing would have been taken very seriously = when the place was built. The lawn rarely gets the chance to dry out betwee= n downpours!

[The Natural Philosopher]

This part of the house was built in the late 1950s. I don't know what's under the tiles, but since I'm situated in an historically VERY wet part of the country I'm guessing damp proofing would have been taken very seriously when the place was built. The lawn rarely gets the chance to dry out between downpours!

Id plump for condensation.

[orion.osiris]

On Thursday, 13 December 2012 00:13:47 UTC+1, The Natural Philosopher wrot= e:

The room in question has nothing in it that gives off water vapour; it's no= t like a kitchen or a bathroom, it's just an empty utility at present. And = before anyone asks, no, there isn't a boiler in there.

I read an interesting tip someplace about testing stone floors for permeabi= lity to water. You take a sheet of glass and place it flat down on the floo= r with a strip of sealant around the edges to make it air-tight. If after a= while you can see misting up on the underside of the glass, it indicates t= he tiles ARE letting water through. Sounds nifty to me, but is the methodology 100% sound, I wonder?

[harry]

not like a kitchen or a bathroom, it's just an empty utility at present. An= d before anyone asks, no, there isn't a boiler in there.

bility to water. You take a sheet of glass and place it flat down on the fl= oor with a strip of sealant around the edges to make it air-tight. If after= a while you can see misting up on the underside of the glass, it indicates= the tiles ARE letting water through.

Or you can use plastic sheet and tape. You need to thoroughly dry the area underneath off first. It can be misleading because the floor may be damp through and through with the condensation. Lift after a couple of weeks and see if it's damp underneath. A late fifties house likely will have a DPM but no insulation under the floor so making a condensation problem worse.

The source of condensation damp does not need to be in the room, in fact it usually isn't. It just needs warmish moist air from anywhere to come in contact with a cold surface. Depends on how the air in the house is circulating. Another clue is if there are problems elsewhere or with black mould.

Best dealt with at source, eg cooker hood, shower extract fan etc.