Concrete paint for sealing

[R]

Why not strip off the existing stuff and tile it then seal them ?

[Rod]

I don't know about 'best', but is this any good?

And they have plenty of things to put on top of it:

(Interest to declare: I work for a company in the group, but didn't know that until today. And I don't have anything to do with paint. :-) )

[Gib Bogle]

The 30-year old house we are renovating has a big concrete balcony, part of which is actually the roof of part of the garage. The concrete has never been coated, and the surface has a crazed appearance. In the last heavy downpour I noticed water dripping from the ceiling in the garage. The water was coming through a crack visible on the underside but not on the top.

I want to seal the concrete, not so much because of the leak, but because I'm concerned about the effect of the water getting into it. Apparently the first step is to etch the surface. My question: what is the best coating for this purpose?

[Clot]

Does the concrete slab get support at its furthest edge from the house? Are the sides of the balcony supported or is it just cantilevered from the house wall? If the latter, is the ceiling in the garage or the floor seriously stained from rust?

I ask because if this is the case then the reinforcement of the slab has been weakend.

Unlikely, but I don't know the set up.

[Rod]

So it is. :-(

Maybe their Road Marking Paint would work outside? :-)

[Clot]

Thanks for the reply. I just didn't wish you to go to the effort of coating the balcony when the serious damage might already have been done.

Good luck and may the weather be with you!

[Gib Bogle]

Something like this:

promising, but this is for interior use. I like the idea of a

2-pot epoxy.

[Gib Bogle]

This part is very well supported. It's about 1.5m x 6m. The outer edge and the two sides are supported on concrete block wall, the inner edge on a concrete beam with a pillar in the middle. There is also a 1.5m x

3m cantilered area, with support only on the inner edge and one side, but no leaking there. There is no rust staining, or spalling, therefore I think that the reinforcing is probably still OK.

[Stuart Noble]

I'd try a coat of SBR. Unlike paint, it's fine enough to get down into the smallest crack

[Tim S]

Stuart Noble coughed up some electrons that declared:

Whilst on my search for a liquid DPM for concrete[1], I kept seeing various Thompson water sealing products for concrete, block paving and brickwork. Seem to be in most builders merchants and some sheds.

When I read the labels, it seemed none were pitched at being a DPM, but were intended for water/dust sealing garage floors, external blockwork and driveways.

Might be something there?

Cheers

Tim

[1] I'm not going to bother - overlaying Marmox board to get a combined DPM and insulation. Seems all the British DPM's are bitumen based - I was after something more like polyurethane which seems to be in use in America.

[Stuart Noble]

I think they're mostly siloxane type products that supposedly don't form a continuous film and move about within the structure. Micro pellets of silicone AIUI. SBR works well on crazed surfaces because, although it's form-filming, it's so penetrative that you wouldn't notice.