Nice video however the vapour is not coming through the wall. The water droplets are condensation from inside of the building. Vapour from within the room is finding a cold spot (the tanked wall in this case) and causing the water beads. Way to stop this is reduce moisture content in room (dehumidifier) or make the wall warm (external or internal insulation). Tanking stops water coming in however also stops the wall from breathing hence the vapour issue. Having recently tanked a basement it is sweating as there is no where for the moisture to go. I intend to build a metal stud wall, 50mm wool insulation against the wall and between the studs, 37.5mm insulated plasterboard on top and then skimmed.
Also when we used to concrete a basement floor we stopped using dpm because When you put a membrane down and the steel and start pushing Wheel barrows about the membrane would always get pierced, so after concreting, when dry we would apply damp proofing slurry before any screeding, and the building inspector loved our idea and recommended it to all other builders 👍🏻👍🏻👍🏻
I used to use this in Brighton all the time, vandex we used £50 a bag 10 years ago, we would have to go back to brick then put a rendering coat on a meter up from the floor to seal all voids , also put a mortar fillet around the bottom of walls and floor and then apply damp proofing slurry in 2/3 coats a meter up on walls and a meter out on concrete floor from the wall, SBR Was a no no because it would affect the guarantee, and once this was done you could bond of hard wall walls before you apply multi finish plaster, 👍🏻👍🏻
Update.... The vapour theory came from the manufacturer tech department. However , due to high humidity, the beading is more likely to be condensation !.
I don't agree....simply put the condensation is from the atmosphere....IT DOES NOT MAKE ITS WAY THROUGH THE SLURRY EVEN AS VAPOUR. IF IT DID IT WOULD BE DAMP THOUGH OUT!!! it is external condensation due to the dew point on the cooler wall surface and the moisture loading in the warmer air next to it.
Thanks so much! I used a bitumen dpm on my wall and was getting water and salts on the surface, with some blistering. I was thinking to switch to the tanking slurry but I suppose I’ll just have the same issue. It’s a very informative video with no fuss. Really appreciate you uploading this.
I thought the information was interesting although I believe the moisture ‘beading’ as said is actually condensation from moist air within the room condensing on the cold cellar surface. If after scratching through the dark areas where water beads have collected the substrate is light grey and ‘dry’ as stated then it is not coming through the slurry but forming on the surface as explained. A good humidistat extractor fan with fresh air supply to the cellar normally does the trick. ! I didn’t think the language was necessary or added any value to the video.
Yep this is my understanding about the condensation. I spoke on the phone to a bloke from KA slurry who told me that it's water proof AND vapourproof. He told me it even stops radon gas coming through! He said that, assuming you've done it properly, any water droplets will be vapour that's already in the cellar condensing on the cold parts of the wall - which, incidentally, is likely to be the parts of the wall that has more moisture on the other side of it.
Agreed. The vapour theory was explained to me by 2 different sovereign technical advisers. I do believe with all the water used to double render the cellar there would be high amounts of moisture evaporating into the cellar and settling on the tanking. Check out latest video 1 yr post job. Thanks
Great video and simple honest explanation of how to do it properly thanks. We have what we think is rising damp in our concrete bedroom floor every thing that touches the floor goes moldy we have no mold on any walls etc the smell comes from the carpet we thought we could seal/tank the floor to stop it can you offer any advice please
Hey I’m from the US. I’m guessing tanking slurry is a crystalline waterproofing slurry. I was going to do my basement. I’m not sure if you ever heard of drylock latex paint. I always thought drylock was BS but the waterproofing ingredient is waterproof. Just wanted to hear your thoughts
I used KA Tanking Slurry about a year or so ago on my damp sub floor in my hallway of my 1930's semi. I got the water droplets soon after as mentioned by other people. After a few weeks/months the tanking, which was done exactly as instructions, started to blow & blister & in parts is now akin to a paste. I have the rest of the hallway, under the stairs & kitchen sub floor to do also as they have the same damp problem. I have no idea where the damp is coming from & the walls seem ok. The damp is about 1 metre in alongside an exterior wall & the house is on a hill. Any advice please? Many thanks.
Great advice, but hoping somebody could help me with a follow-up question please. I had a small amount of damp in my office.I have removed the plaster to reveal the breeze blocks, bonded with a pva/water solution, and applied 2 coats of tanking slurry. The water droplets you mentioned have formed over the previously damp area. I now need to re-plaster the wall but I’m concerned about doing so, because it means applying plaster to an area of the wall that is covered in condensation. The office does get very cold because it is not insulated and is effectively a standalone alone room bolted to the end of the garage (I simply heat it with a fan heater when I’m going to use it ). What, if anything, do I need to do before applying the plaster? Thank you.
As mentioned in video. You must apply the damp proof renovating render after the slurry. Once that is set, then put whatever you want over that. You cannot plaster straight over tanking slurry, it will fail due to the wall being too cold. The renovating render warms the wall so as not to attract condensation.
Great explanation. Ive got a brick out building with hinged steel doors (20mm gap under them) and slate roof. One of the walls is up against land behind it so ive tanked the wall as you mentioned but its getting the condensation droplets now. Whats the best method to prevent this in an unheated building. I dont think a high up roof or wall vent would fix it, maybe something to adhere to the tanked wall like ply wood or dabbed board so the cold air doesnt hit the tanking? The earth behind has been dug out and filled with pea gravel too.
@Dan no shouldn't because it stops the cold barrier so the moisture in the air won't condense. If a bit of moisture does get behind it, it can't travel through the back of the insulation on the board anyway
@@craigofyorkshire3397 no its neither as its always dry now, just them odd days when the dew point condenses, i dont remember seeing it for a long time now but im not in it daily
What is the best way to dry out the wall if there is beading water vapour on it? Do you need to dry it our before the render is applied? Good to see that beads of water is normal. Was worried :)
Can anyone reply please. Can I do this and laminate over it . ? Obviously I am going to put underlay. But is it ok to apply this and laminate over . Thank you
We have applied correctly but the condensation is massive amounts where the wall is up against the earth behind it. Half the wall is soaking and its pooling on the floor. If this is just condensation are the items we store in the garage still going to gather mould? We done this as our garage was useless for storage. Everything would be damp and eventually mouldy 🙈
Scrape the tanking, if its dry where you scrape then it's condensation. If it's condensation then cardboard boxes love to go soggy and mouldy in that environment. Think ventilation next.
@@cdracos1 thank you, yes it's condensation but it only seems to be effecting half the wall where we had the damp before. The part that has the earth against it. We have a dehumidifier and I'm now thinking of maybe a vent somewhere. I hope it will be enough as I am not sure what out next step can be. We can't dig the land up as it's our neighbours that's against the garage. Thank you for your reply
Question... I recently ( 6 weeks ago ) Tanked one wall inside my garage with two ' Thick / Generous ' coats due to water ingress due to a neighbours ground level / property being against his one wall of my garage. My worry is. every time we have a down fall of rain, the following day wet patches appears in random places all over on the tanked wall in question ??
1st you scrape , with a knife one of the damp patches. If you expose a lighter dry surface then it's condensation build up due to higher moisture in the air due to the rain . The solution to this is to apply a 12mm + layer of ready render warming coat . Also a functional air flow via extractor fans is good practice. If after scraping the damp patch you find you tanking slurry is damp beyond the surface then it's your tanking that is at fault. Either poor product, mix measurements ,application technique ,thickness or wall preparation before tanking application. Even missing anti sulfate can fail slurry due to salts penetrating the slurry.
Hi cdracos1 thanks very much for this video. I have applied 2 quite thick coats of cementone tanking slurry in my garage. The parts of the wall that were damp prior are still damp now over 2 weeks later, and I'm not sure whether the tanking has worked properly. I noticed the vapour condensating on the walls during the first couple of days while the majority of it was curing, but the "damp patches" just don't seem to want to dry out. Would you recommend I wait longer or just stick another coat of tanking over the bits that haven't dried? Thanks very much for your advice! Joe
Jonathan Regis yes , however its impossible to achieve even thickness if your initial render coat is not perfectly flat. Also it would be very difficult unless you mixed it thicker , not advised.it would go off super quick and may leave open pores. I have seen it done on floors tho.
I have tanked meter from floor 2 coats all prim and proper and dried out 100% but noticed when it rained then after it was fully dry dark areas appeared on the slurry wtf does that mean cheers mate
Hi I’m having this problem now On my chimney breast so we removed the breast and now it’s still on wall ? Tanked one coat and it’s not drying one week later, suspect condensation but previously tore moving the chimney breast this wet the plaster boards ? How do you prevent this and where does the condensation go if you cover it over with membrane ?? Tia
Thank you for this video. I have applied 2 coats slurry, someone suggested I should have sprayed with anti-sulphate. Would you recommend this or should that have been done prior to slurry? Also can you recommend what insulation to then use after plaster is applied? Many thanks, Heather
Anti sulphate needs applying to the Bare brick first then it needs applying to the rendacoat. If you have already completed the slurry work then it is too late . it will not absorb.
You now have the worry that effervescent salts may blow your render coat and tanking slurry off the wall. Regarding insulation coat, we use sovereign Light ready render coat at minimum 12mm thick. The same as in the video, nightmare to apply.
Generally no drilling is the rule. However I've heard you can drill a big hole I.e 15mm, then fill the hole with a specialist tanking product , let it set then drill and plug 8 mm . Sovereign chemicals do product I think. They have ytube videos.
It should be mixed with SBR and water. Meter reading may be picking up beading or condensation. Only way to tell it scratch tanking at look for whiteness as shown in video.
One more question ? I have applied a 18mm render with Sika 1 to all the walls, the basement is 2.8 m deep but not the whole area is underground only about 1.2m is below ground level, should I tank the entire wall or just the part thats below ground level ?
Hi there . I'm almost ready to tank my cellar out but on 2 walls I've got cement render and it's solid so my question is can I tank over the render or do I need to treat it with something first ?
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