Sea-facing gable-end wall to paint

[Jason]

I am having my chimney rebuilt in a few weeks time, and to do that, the gable-end wall needs scaffolding. Taking advantage of that, I would like to paint the wall, since I cannot get to it without the scaffolding.

It is a big North East-facing wall, very close to the sea, and so gets a lot of wind and driving rain. The wall also already has two layers of rendering - an underlying layer that has probably been there thirty years, and a new layer that is more like twenty years old. The outer layer is a very tough layer of some kind of concrete, and is very hard almost to the point of feeling brittle.

We don't have any damp problems on that wall, at present.

Now the question is, what should I paint it with? I am looking for something that will last a long time (10+ years), and will not cause any dampness. I have no idea if some paints will seal in water and cause damp, or cause the rendering to detach. Not knowing what the rendering is treated with (something that makes it waterproof, no doubt) I also have to worry about what will "take" and not peal off.

Any advice on what I should be looking for, while the clock is ticking (doing this in three weeks from today!)

Here is the end wall, courtesy Google Street View:

green is mostly gone now, and the chimney is leaving rather a lot more than this!

Thanks,

-- Jason

[Jason]

On 10/05/2011 20:55, Jason wrote: ...

I was being lazy. Here's a proper photo I just took:

pictures of the rendering up close:

idea what it is though, but does feel kind of brittle, but is *very* hard and is about half an inch think.

Ideally this wall will be insulated, but I'll be saving up for that (or keeping my eye open for a grant to help).

-- Jason

[Tabby]

Fwiw lime is durable, doesnt cause damp leading to damage, and handles salts in a way that does not damage the wall underneath. Its also exceptionally easy to apply and extremely cheap. It lasts a good deal longer than 10 years.

NT

[Jason]

There is a 300 year old house down the road on the sea front, painted with lime, so this may be the job, so long as it sticks:

JJ

[John Williamson]

It looks like a Tyrolean type finish, and if it's anything like what I had chipped off my place a while ago, it can separate from the substrate and lead to some very interesting patterns of damp, while showing absolutely no cracks whatoever. Mine was over a sharp sand/cement render, which took a *lot* of getting off, and was standing up almost independently of the wall it was "attached" to. Whatever you paint it with will probably need to be sprayed on.

I had the whole lot removed down to the brickwork and then the walls were lime rendered. With any luck, the job'll last longer than I will. Or you can use an insulating render, which pays for itself over time.

used to be the norm for masonry paint.

[John Rumm]

Its sounds like two coats of render are pretty much going to waterproof it anyway. So I would expect that if that has not caused dampness so far, painting it is unlikely to make it any worse.

For masonry I usually use:

[Jason]

That sounds like the stuff. Before the side shed was built, there was an enormous bubble in the render, with a 7-8 square metre area not even touching the wall. But it held on firmly, did not move, and was like that for ten years without shifting. And yes, no cracks, which is surprising considering how much the house moves around from one year to the next.

-- JJ

[John]

I don't know if they do anything suitable for your situation but Liquid Plastics is always worth a look. I've used their K501 on brickwork with great success so you may find something here:

[Jason]

Ta - I'll have a good read (lots of data sheets and case studies there).

-- JJ

[stuart noble]

>

I'll second that. My gable end wall is very similar, but faces SW, the worst aspect for paintwork IME. The pliolite paint shows no signs of degrading after 10+ years, whereas ordinary masonry paint (including Sandtex) applied before that hadn't lasted at all well. Pricey, but well worth it, especially if you need scaffolding to get to it.

[Tabby]

I've heard people say it wont stick to concrete, but I've yet to encounter any such problem. If there is a sticking issue, adding 1% boiled linseed oil may solve it.

NT

[stuart noble]

And pray it doesn't rain....

[Tabby]

just check the weather forecast. Lime paint takes a day or so to become rainproof.

NT

[Martin Bonner]

Very much agree.

That is not my experience. When I applied it myself (made up from lime putty + water+milk) it lasted about three years. Getting a professional in to apply it, and buying it ready made, it lasted about five.

Silicate paints are getting good writeups. They are more expensive than limewash, but it may be worth it for the OP given the longer life. I haven't ever used them. For example:

[Tabby]

I didnt add milk.

NT

[stuart noble]

is not listed in the ingredients. Perhaps they should rename it Greenwash paint

[MuddyMike]

Why do you want to paint it? Whatever you use it will need doing again, and again, and again. I vowed never to have another house that needs painting after owning a painted, rendered house for 23 years. The longest lasting paint I used was Micatex by Permoglaze ( I think they call it Permotex now) that weathered far better than Sandtex, but if you must paint that wall use the smooth version it goes much further.

Mike

[Martin Bonner]

Interesting. Maybe lime sticks better to concrete than to clay lump. (Which wouldn't be totally amazing.)

[Jason Judge]

Why? Strict instructions, for which I have been arguing against for years.

This particular wall faces onto a primary school playground next door, where my better half works. It is got grey and patchy over the years, and just looks untidy. I guess in the end it is the thing to do for the neighbourhood.

-- JJ

[Jason]

On 12/05/2011 00:14, Tabby wrote: ...

Hehe - the weather forecast. If it were April, I would to avoid painting due to the showers. May should be okay though.

In reality, a new water-butt I put up at the start of April, remained empty until a week ago, and then filled up in one hour flat.