Painting Block Built Garage And Weather Protection.

[Ratty2E]

During the very wet weather my garage walls let in water and I am keen to try to stop this happening again. The previous owners built it with single wall breeze block, but it was never rendered and now due to it's proximity to fences/greenhouse/large bitey shrubs it would be impossible. My only option is to paint and even that will be character building in places. Now would any of you paint on a coat of water seal stuff too, either before the paint, after or not all.

[RATTER15]

I would seal it with a waterproofer and then use a good quality exterior paint like Weathersheild.

[The Builder]

Unless you use waterproof render, Ratty, it'll do nothing to keep out rain. I've seen 9" (225mm) rendered blockwork where rain has easily penetrated if facing West.

Even modern masonry paints won't keep it out. Paint only for decoration if you'd like to, but a couple of coats of silicone based sealer is the easiest solution for a garage............

http://www.screwfix.com/p/thompson-s-water-seal/52043

[RATTER15]

Waterproofer/sealer not the same thing then?

I thought they were.

[The Builder]

In this case they certainly are, Ratter.
I wasn't disagreeing... just didn't explain it clearly :o(

[Ratty2E]

Hi Builder and Ratter thanks for your advice. So you recon sealer first then paint? I was concerned that the sealer might stop the paint 'sticking' properly.

[The Builder]

Good question, Ratty.

"Water Seal" should only be applied to "weathered" surfaces. If you paint first, then it could be ages before you can treat it.

If you treat first, then I guess there could be a problem with adhesion. Their data sheets have no mention of this. Ring their Technical people for their advice. I wouldn't have thought that this was a problem. The treatment soaks completely into the blockwork. It shouldn't act as a barrier, but I'm not sure.

If you're not too worried over appearances, then I would suggest simply treating the blockwork, and leaving it at that. It's very effective.

[Ratty2E]

Ok thanks Builder, I would like to paint it to match the house and it's a bit ugly as it is. How long does it take to be 'weathered'? I would rather do it all at the same time so will see if I can find out if I can paint over the water seal.

[The Builder]

Another good question :o)

A top quality masonry paint might take years. I guess you could use limewash or something else that's porous, but you wouldn't match the house.

One way around it ............. slap on a couple of coats of sealer first. If access is difficult, use a long handles roller.

then ... roll on a coat of diluted PVA mixed with some builders' sand. Dilute 5:1 PVA:water. This will give the paint a "key" to hold on to.

I'm making this up as I go along, Ratts, but I'm confident it'll do the job :o)

[Ratty2E]

I'm full of 'em today Builder ;-) well I've been on the Thompson website and apparently I can paint over the sealer with water based paint after 30 days. If I paint first I have to wait a year before I can put the sealer on. I think I'll take the first option. Thanks for your input.

[carrust]

Have you got space to clad it in wood?

[Ratty2E]

Not really Carrust, I've only got a foot or so gap in places to get to it. Painting it is going to take imagination and a telescopic pole.

[heathfield]

Sandtex advertise their masonry paints as being 'waterproof' and 'breathable'. Thompsons say their Water Seal can be overpainted after 3 to 4 days, but add that an oil-based paint should be used, which masonry paints aren't. Thompsons advice about waiting 30 days means you could use a masonry paint as a finish after that time. Personally, from having Santexted the front of my house many years ago, with excellent results, I'd go straight for that. If the breeze block surface is rough, take extra care not to leave evn teensy bits of bare surface. This might mean a couple of applications.

[Ratty2E]

Thank you Heathfield, I have got Sandtex paint.