Tanking a 400 year old stone cottage

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Chrisamyphillip

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Floor is cement and has a membrane. Floor is dry.

Outside walls are rendered and not leaking/cracked.

Walls are 18-24 inch thick.

I have damp walls 'up' approx 2 foot on met walls.

I was going to tank using Febtank.

Internal walls are cement render finish and am wondering wether I hack this off to get to stone (all sorts of stone!) and paint the Febtank slurry on then re-plaster using renovating plaster.

Question - the internal cement render is solid, not flaky or soft, do I really need to hack this off OR do I simply tank onto this? It is just a reading damp!. If I hack off to the stone, the stone itself will read damp, I'll tank onto that dap stone and serenader with renovating plaster…..

Dilema…

Yes, usual thoughts re old walls/cottage breathing, ventilation etc etc. I have only lived here a year and we 'vent' it a lot but these walls have not dried much. There is the usual mould growth due to lack of previous circulation; clean it, vent room - hey presto.

Surveyor recommended tanking……

Applying Febtank onto cottage 'rocks' will be fun, the Sovereign router is to render then tank - would be easier applying the tanking to a smoother surface. Which way around, I don;t think makes a damp proofing difference - i.e. Febtank onto stone then rendering, Sovereign, rendering then tanking onto rendering.

Maybe I tank onto the cement rendered walls and just don't hack off at all :(

Thoughts?
 
Somebody painted the walls with an acrylic type paint (won't help with the breathing). The dark line is obviously where I removed skirting.
If you look carefully, you can see the floor dpm (blue)….
 

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Is it rendered to the floor? Take some pics of the whole room also the opposite side of the walls that have a problem. It originally wasn't damp so you need to go back to the way it was something has changed which has caused the problem you need to suss that out first :)
 
The rendering is to the floor. The damp readings increase as you go up the wall from the floor to a distance of approx 0.5 m

The floor is dry and the wall is dry up until the floor DPM stops (approximately 2 inches), so in summary I suspect that the damp below the floor is barriered by the DPM and 'pushed' up into the walls.

Effectively, if I tank, I will be extending the DPM further up the wall and simply cause the damp that is originating from below the floor DPM, further up the wall above the point that the tanking stops.
 
The sovereign system works 100%. Hack off back to stone, anti sulphate, Render then tank, slurry coat and plaster out withe renderlite backing and white finish. If you follow to the letter you won't have no problems. The H8 system is on sovereigns website.
 
Re DJM68….

In my original posting (ignore typos), what's stopping me not hacking of back to stone? The current cement render is damp, if I hack back to the original stone, it'll be damp undoubtedly.
 
just done a job in putney london, job just like yours wet black mould etc . this was soft red brick 9 "we hacked off the killer sand cement dried it out for 4 weeks .plastered 3 coat inside fat lime. Outside nil 3.5 and quest what its now dry as a bone should make video one day .
 
seanlar said:
just done a job in putney london, job just like yours wet black mould etc . this was soft red brick 9 "we hacked off the killer sand cement dried it out for 4 weeks .plastered 3 coat inside fat lime. Outside nil 3.5 and quest what its now dry as a bone should make video one day .
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Re Seanlar….. So basically you used the fat lime to allow the wall to breath, so any damp in wall simply evaporates/breath naturally.

I don;t follow the second part of your message - wrt nil 3.5?
 
flynnyman said:
How are you getting your damp reading and did you do the reading yourself? Where is the damp coming from?
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RICS surveyor took measurements - I had take 'basic' relative readings with a non specialised damp meter to get 'relative' readings to good dry wall/surface.

The water is a combination of rising and penetrating damp. The penetrating damp has been fixed but obviously the rising damp cannot be stopped as solid stone wall built on no doc and expected that any damp rising under the floor DPM is making its way to the edge of floor and 'up' walls (see my earlier explanation).
 
A combination of two? Let's think about that for one second, you have water coming through a wall which by the laws of gravity will find its way down to the ground, you agree? Then you have another mysterious thing they call rising damp that defeats the laws of gravity and rises up through a wall and keeps rising as if like magic, you agree? Now In this partial case we have both of these problems happening so how do we determine which water is going down and which water is going up? You took basic readings with a non specialised metre which is no different from any other metre apart from price but does the same thing which is not what it was designed for. The other fella took measurement could you explain a bit more please? Why do you think all of a sudden after how many years of this house being built it suddenly caught that horrible illness they call rising damp? which incidentally they have been trying to find a cure for and used no ends of medication which up to now has not cured it? I will tell you why it's because the actual desease does not exist :)
 
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