Sealing a garage base to reduce compensation

[Bert Coules]

Harry,

Ah right, thanks.

That might be tricky at the moment, unless we can find some way of drying out the floor. The condensation that this whole enterprise is meant to cure, drips like mad...

I'll investigate the possibilities. Many thanks, again.

Bert

[The Medway Handyman]

Hire a drying fan or a de hum.

[Bert Coules]

Good idea, thanks.

Bert

[Grimly Curmudgeon]

Five pound notes from FIT payments. A kind of papier-maché effect.

[Bert Coules]

Just back from a long look at the garage in question. The inside of the roof was dripping copiously as usual, except for a small area alongside the one part of the corrugated roof which isn't fitted with the 6"x6" metal angle on the outside - in other words, the gaps caused by the corrugations are completely open to the air. So the "increase the ventilation" suggestions are clearly on the money, even if it won't be easy to do.

The floor was certainly wet, but not all over: the front half of the garage (by the double doors) was uniformly damp, the rest only damp in scattered patches. Does that knock on the head the theory that water is penetrating up from beneath the base? Wouldn't that happen all over?

We dried things off as best as we could and left the doors wide open to help the rest evaporate. As soon as it's practical we'll lay a waterproof membrane over the whole floor area and see what difference that makes, if any.

Thanks again for all the help and advice.

Bert

[Bert Coules]

A quick update: laying a waterproof membrane over the floor area has reduced the condensation problem a good deal. Which suggests that painting or sealing the concrete floor would be a sensible course.

Bert

[polygonum]

Good - now want some dry weather to allow it to dry out as much as possible. Do I remember you mentioning ventilation? Open anything possible as much of the time as you can.

[Bert Coules]

I'm going over there soon to check the state of the floor underneath the membrane. Presumably, if the rising dampness hasn't been able to evaporate, the concrete is likely to be very wet.

I've also wondered about replacing the one fixed window with one that opens, or perhaps fitting one of those non-powered ventilator fans.

Bert

[Paul D Smith]

A quick update: laying a waterproof membrane over the floor area has reduced the condensation problem a good deal. Which suggests that painting or sealing the concrete floor would be a sensible course.

Bert

-----

Haven't seen the preceding discussions but there is some stuff you can effectively "soak into" the concrete which both solidifies it and presumably makes it water proof. I used this on an internal concrete floor which was very powdery and it worked a treat.

Cementone SBR is the name - someone else on the NG will be along in a moment to explain why it is/isn't a good idea for your problem (apart form the cost!).

Paul DS

[Bert Coules]

Thanks for that. The problem with the floor is - so it seems - that it soaks up a lot of moisture from the ground which then evaporates only to condense on the inside of the corrugated metal roof.

There appears to be quite a variety of products to seal concrete against water from above, but do they work in reverse, so to speak? A layer of paint or sealant will presumably prevent any water coming through from beneath but wouldn't it be damaging to the concrete to have all that moisture trapped in it with nowhere to go?

Bert

[Paul D Smith]

Thanks for that. The problem with the floor is - so it seems - that it soaks up a lot of moisture from the ground which then evaporates only to condense on the inside of the corrugated metal roof.

There appears to be quite a variety of products to seal concrete against water from above, but do they work in reverse, so to speak? A layer of paint or sealant will presumably prevent any water coming through from beneath but wouldn't it be damaging to the concrete to have all that moisture trapped in it with nowhere to go?

Bert

----- It was recommended to me to essentially dilute the SBR with water and then "water" the concrete using a watering can, the intention being that the SBR solution soaks as deep as possible into the concrete. It seemed to absorb a great deal, but then my concrete was already poorly laid and very powdery. However I could not tell you how deep that might be, and I certainly wouldn't do it in your garage at the moment because the concrete is bound to be wet and thus won't absorb.

I'd wait until the middle of summer to even try this, and if you've got power might even put in a dehumidifier for a week or so to really try and suck any moisture out of the concrete before starting.

Paul DS