Put it wherever you like :-) Best on the outside of course, but all forms of tanking are a compromise. You're basically allowing water into the wall but trying to stop it coming all the way through to the inside. Bitumen is one way but I'd guess pliolite would do the same with a much thinner coat.
Used to be....
If it breathes, it surely doesn't matter whether it's in or out. And bitumen breathes too you said?
You'll have gathered I don't have much time for this breathing lark. For something to *not* be breathable it would have to be airtight, which is quite beyond the capabilities of anything you can tosh on with a brush.
I would add that IME dehumidifiers will always pull in gallons of water and, unless the area is totally sealed, most of it will be sucked in from outdoors.
20% seems pretty high to me, surely you would be aiming for much less moisture (10%?) to avoid shrinkage ... assuming the end products are to be used indoors?
Alex
For goodness sake, it still is - have a quick look at the URLs I included earlier. It's widely used.
If it "breathes", and it is inside, then water (vapour) will get in - the point of "breathable" paint is that drops of water landing on it don't go in, but dampness can come out. If you apply a breathable paint *inside*, then any damp getting on the wall outside can still get through in the form of vapour, perhaps condensing nicely on the inside of the building.
Bitumen is *not* "breathable". It forms an impermeable and very durable membrane, which can deform with the substrate, and is used for tanking applications, being especially suitable for this sort of thing.
You won't get much coming through a properly-applied coat of bitumen emulsion (described earlier) - that's what it's *for*.
I agree completely. Did our forebears have de-humidifiers running all the time? No. Mind you, they did not have bitumen emulsion until.. oh, say a hundred years ago, or so, or Pliolite paint either. They must have been really soggy people.
I'll try it on some chipboard, leave it in the garden, and see if it gets wet. Reminds me of some tests I did a few years ago to see if surface coatings could prevent the shrinkage in 4" x 1" softwood (it was important at the time). IIRC *several* coats of acid catalysed lacquer delayed the process *slightly*. It still went from 17% moisture content down to 8% and shrunk in width accordingly. Although the wood looked like a solid lump of plastic, it was obviously breathing nicely. Yeah, I know, the coating wasn't flexible enough. Okay I'll try it with bitumen emulsion maybe.... As for the OP's garage, why not use plastic sheet? Now that really doesn't breathe
Yes, from that point of view you're right Alex. But I think it would be a difficult job trying to keep it down to 10% in an unheated garage, even with waterproof walls ;), as the moisture content in the timber will always try to equate with the surrounding air. On average, new timber at the merchants has around 18% and hardwood flooring is usually kilned down to around 7%. The 20% maximum I quoted is simply to ensure there's no risk of rot attack.
Just to close off this thread - this is what I ended up doing... Thanks to all who posted originally and set me looking a various new options.
I spoke to Antel
- not that far from where I live, and a chap very kindly came out and took at look at what I was trying to do.
He recommended two coats of Tanking Slurry painted on the walls followed by two coats of Water Based Epoxy.
On the floor he suggested just two coats of Water Based Epoxy. If I wanted a smoother floor (which I did) then a coat of a cement based Self Leveling Compound mixed with SBR addative under the Water Based Epoxy.
First off I added a small fillet at the wall/floor join of mortar/SBR mix.
And that is what I have done... Not cheap but now looks just great. This is supposed to be industrial strength stuff so it should easily do the job required... We shall see...
Three new photos added 10, 11 and the finished article 12!
Looks good... thanks for posting the final result!
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