Applying limewash to cement render

[Zebra]

Apologies if this has been covered elsewhere. I have various surfaces externally on my house, which are to be rendered.

The woodfibre external wall insulation will have a proprietary NHL-based lime render.
The soft porous old brickwork has a putty-based lime render.
The new extension is in blockwork, not yet rendered.
The front is modern brickwork, not yet rendered.

I was going to buy enough of the proprietary NHL-based lime render to do the whole house and have it through-coloured so I don't have to paint it, but this solution is working out quite expensive.

So I'm thinking of having a sand and cement render on the modern parts of the house where it doesn't have to breathe, and painting the lot with limewash or a breathable paint.

The proprietary NHL-based lime render which comes with the woodfibre insulation is apparently compatible only with Beecks Renosil or limewash.

Has anyone tried Beecks Renosil? Has anyone tried painting a cement render with limewash, and what did it look like, any tips?

Thanks!

 

[Moo]

I'd be interested in the answer, too. There's a patch of cement on one of the cellar walls in our new house.

 

[Pford75]

We used Corical Lime from Telling Lime Products. We applied it to soft red brick, flint work and some cement render. The flint work and cement render had a coat of their Unilit product first (which is a lime slurry) before the limewash. The end result is very impressive and the Unilit coat helps adhesion and smooths out the texture.

 

[88v8]

Some of our house is cement-rendered, so I have this problem to come.
From what I have read, limewash will be less durable over the cement render as it will not sink in. Where well-applied multi-coat limewash might last 3-5 years over lime, you may find yourself re-applyig it to the cement after 2 years, depending on weather and exposure.

Ivor

 

[Zebra]

That's really useful to know Ivor, thanks.

 

[Alex]

Hello Zebra,

We tried limewash on cement render about 3 years ago as a test, luckily it was around the back of the house as it didn't make it through the winter, it just flaked off. There is no sign of it at all now. Hope this helps.

Alex

 

[Zebra]

Thank you, yes, that helps very much. Reckon I won't have cement render then, I'll just find a cheaper way of making my own lime render for the new build bits.

 

[Pford75]

Just to provide some balance, we finished our limewashing in August last year. We had a pretty harsh winter and lots of rain etc. since....but the limewash on the cement render is still very much ok. Corical lime includes crsuhed marble dust to make it more durable

 

[88v8]

Mmmm, interesting. I have noticed that the addition of stonedust or silver sand produces a very hard and quick set when pointing. Hadn't thought of it for render.

Ivor

 

[AMc]

Thank you, yes, that helps very much. Reckon I won't have cement render then, I'll just find a cheaper way of making my own lime render for the new build bits.

I know that sounds like a good idea now but I would strongly recommend that if you can go for the same self coloured finish everywhere you'll be saving yourself decoration costs for the lifetime of the render and the potential for a mismatch in finish.

In my renovation I made a few decisions that saved me a few quid at the time, when money was running short and have since come back and bitten me in the wallet and the heart. There is nothing more soul destroying that doing a job twice or three times or four because you thought you were saving a little money.

 

[Zebra]

Hmmmmm, hmmmmmmm, yes, s'pose, that's a very sensible point of view....