tanking

Smudger1

Well-Known Member
#1
Hacked off a meter and higher well above damp areas of an internal room using perma gard gear. I dpc`d the brick internals and cavity areas sprayed walls with the anti sulphate and flat tight rendered with thier anti salt & waterproofer addative in the mix. let all dry then tanked 3 good coats on all walls especially the thick stone walls down and about 8" onto good floor with dpm etc under it and well coated wall joint to floor. its been drying out over a week, aired the room well and using dehumidifier.

The worst few original damp walls are still dark/drying low down and small moisture beeds showing on surface of a couple where wall n floor meet . How long does it normally take for tanking coats to dry out all over so i can get them rendered and finished ?
 

carlos

Private Member
#2
Years back I was told that if the substrate is still damp behind the tanking will never change to the lighter colour your looking for the those areas.

Not sure if I really belive it but it's what we have always done.

The beads of water are probably condensation.
 

Smudger1

Well-Known Member
#3
thanks carlos i will give it till next week to see if the last bits dry out, what about a bitumane type black tanking or some other better product just over those bits before render just incase ? which after the 3 good coats of the cementatious ive applied will be dissapointing if needed .
 

Smudger1

Well-Known Member
#4
cant see an edit icon on this forum? also wanted to ask if forced heat on it would help ?
 

adapt

Active Member
#5
Don't bother with a bitumane tanking that stuff is not as good as a cement based tanking system, and also its prone to degrading due to the salts attacking it.

Carlos is bang on the walls don't dry out.

your applying a barrier to stop it coming through after all.

We just get on it the next day, no waiting for it to cure as it needs to dry out together.

The trouble is leaving it to dry out means the wall will need to be primed again to kill the suction.
 

Smudger1

Well-Known Member
#6
I gave the tanking a blast with torpedo paraffin blow heater and dehumidifier on, it took a lot of the moisture off without cracking or any probs.
i usually give tanked surface an sbr slurry before rendering with the anti salts n waterproofed add mix stuff, is pva slurry mix or blue grit just as good or better to prime wall before rendering ?
 

adapt

Active Member
#7
Don't go near PVA that is no good for what you want SBR is the way just prime it with a 50/50 of sbr and water.

There are times when you have to put cement in the primer but usually if your going onto an old substrate and you need a good key.
 

Smudger1

Well-Known Member
#8
After it rained heavy over night the dark patches behind the tanking low down got bigger and the surface is wet to the touch. I rang perm gard and he said that after the way I've done the job and the 3 good tanking coats there is no way damp is getting through it, and the wet surface is condensation even though it ain't on any surface other than the dark patches.

It's had plenty of fresh air and dehumidifier etc drying for nearly 2 weeks I gave it a blast of heat and it did dry off without coming strait back wet so maybe it is just on the surface ?
He recons get a 10mm coat on using sharp sand and their additive and crack on it be fine ?

although I gave all hacked off surfaces a good anti salts spray and the additive in the backing coat before tanking there are a few salts showing through on the tanking surfaces too. I will give em another spray before render coat.

ive done everything by the book even a bit over kill to make sure it's done once and properly but not as confident with the product as I thought I'd be !
 

carlos

Private Member
#9
The permaseal tankin is not sulfate resistant. So when salts are present your meant to scratch coat with sulfate resistant cement.

Or use sulfatex tanking sold by permagard as it is a sulfate resistant tanking.

Hope this helps.
 

carlos

Private Member
#10
They don't tell you that though. We only found out after having problems.

Also condensation is a real problem on tanking and I would bet it's what your getting on the surface.
 

Smudger1

Well-Known Member
#11
Thanks Carlos I gave walls a good soaking of anti sulphites and used the additive with the anti sulphites in render to flatten of before tanking. you'd think that would be enough to kill the salts !
I'm going to believe the perma gard guy that said the tanking is working and its just condensation on the surface he should know his product and what he's talking about aye ?
ive given the tanking a spray of anti sulphites today to kill the salts more and got all the rules up ready to start rendering tomorrow again with the additive they supplied in it then its a question of how long it take to dry enough to get it skimmed n finished !
 
#18
Been using that ka tanking slury on to brick,stone before you render
great stuff never had any bother with it bit pricey but dose a great job
 

gps

Private Member
#19
Been using that ka tanking slury on to brick,stone before you render
great stuff never had any bother with it bit pricey but dose a great job
I use that myself but it's one of the cheapest around 30 a tub with vat
 

Smudger1

Well-Known Member
#24
What was the end result then all ok ?
Seems fine, but i let s&c render over dry out for a couple of weeks and gave couple of patches that were drying slowest a quick spray of anti sulphates which seemed to speed up the render completely drying out ? I had plenty of other jobs to get on with here so started final multi coat skim yesterday over bone dry render with blue grit over and its drying well so far. In fact im sure after following the process and more its done the job .
 

adapt

Active Member
#25
Well I just get on with it and don't worry about drying out, rather it all dried out once complete, remember every time you add a coat of anything your applying a lot of water as its in the mix.

I did a re-skim for someone who had penetrating damp from a leaking roof of a bay window, he got the roof fixed but I told him there was a lot of moisture still in the wall and it might take months for it to dry out.
I just got on with it and told him to get a dehumidifier to help it dry.

If you were going to wait for walls to dry out you would lose out on work.
 

Smudger1

Well-Known Member
#26
The walls were done by others twice before and failed so i wanted to be 100% i did it right and final which i have its all decorated now and looks the bizz. There was no time restraints on job so came back to it as i pleased while doing other work there and elsewhere otherwise i would have hit it quicker while still being thorough getting it water tight.
 

adapt

Active Member
#27
Its always the way, the better man always has to repair cock ups from other so called experts. sounds like you have done a good job there mate.
I am always seeing cock ups from other builders and I always feel sorry for the customer having to pay twice.
 

Smudger1

Well-Known Member
#28
There are 4No. 4" vents in that room of which 2 are showing a bit of condensation around them now, i am thinking due to cold spots around the vents it might be better if i block them up with some 4" jablite ive got left over from a floor i did to seal them air tight and make warmer in the area affected ?
Also i saw some electric air exchange type machines somewhere mounted in ceiling to attic that pressurize the air forcing any condensation out ! any good ? If so i may try them in couple of properties that have some condensation problems.
 

adapt

Active Member
#30
I see condensation all the time, its only mainly due to peoples lifestyles, yeah the piv works but so does opening a window two when you have been cooking or used the bathroom. people feel hard of opening a window so they are trapping in the humid moist air and all it does is condensates on the coldest surface.

How did you get on with that job all sorted ?
 
#33
After it rained heavy over night the dark patches behind the tanking low down got bigger and the surface is wet to the touch. I rang perm gard and he said that after the way I've done the job and the 3 good tanking coats there is no way damp is getting through it, and the wet surface is condensation even though it ain't on any surface other than the dark patches.

It's had plenty of fresh air and dehumidifier etc drying for nearly 2 weeks I gave it a blast of heat and it did dry off without coming strait back wet so maybe it is just on the surface ?
He recons get a 10mm coat on using sharp sand and their additive and crack on it be fine ?

although I gave all hacked off surfaces a good anti salts spray and the additive in the backing coat before tanking there are a few salts showing through on the tanking surfaces too. I will give em another spray before render coat.

ive done everything by the book even a bit over kill to make sure it's done once and properly but not as confident with the product as I thought I'd be !
Never use a dehumidifier its probably had all the moisture dragged out of it too soon and f***ed it