Rendering victorian House

[parksy]

Hi All,
We have an Early Victorian House in North London and have been renovating it. The lower half is rendered but the property has been council owned and as such the original integrity - lime render and lime mortar has been replaced with concrete render and cement based pointing.

The top half is old yellow brick - which is supposed to be pretty porous - and I have been told that the lower render need to be breathable because the water absorbed in the top half needs to be able to be expelled in the bottom half.

The rendering now needs replacing. The local conservation officer has said that they recommend 1:1:6 cement: non hydraulic lime: aggregate.

I have been getting conflicting advice. I am aware of the issues of breathability, flexibility etc with Lime but wanted to draw on some of the experience on here.

Will a 1:1:6 mix have any breathability at all?

Is there any advantage to going with a lime putty if using a 1:1:6 mix?

Will we be able to get a smooth finish - as opposed to a sandy finish? I know we can coat it but presumably that will reduce any breathability that it might have - assuming that a 1:1:6 mix will retain some breathability!

I am reluctant to go for a waterproof coating type of solution - or is this silly if I already have cement pointing and am planning a 1:1:6 mix?

Would be interested to hear thoughts and advice from those with direct experience - advice so far seems to split into ardent cement fans vs ardent lime advocates....

Many thanks in advance.
Chris

 

[tommyl18]

i would use a preblended render which allows the walls to breathe such as k rend base coat or weber rend they are a one coat render but have additives already added to allow for movement and for pourous walls etc.
it will be good to use either way wether you have lime or cement mortar underneath

 

[parksy]

Are you thinking of something like K Lime? http://www.k-rend.co.uk/product-range.aspx?title=K Lime

I am wary about putting something synthetic onto an old building - it just doesn't seem right - but the blurb sounds good - the perfect combination of old specifications (breathability, flexibility) with ease of application. Is it that good? Have you used it?

Do you need to use breathable paint?

Chris

 

[tommyl18]

yea id use that over mixing seperate sand lime mix anyday its brilliant stuff i use it all the time the only down fall is its a bit more expensive people have a misconception that because its in a bag and you just add water that its not sand and cement or lime based but it is the same as knocking it up by hand but it is just premixed before it reachs you which is better because its consistant, its more reliable because you know there is always enough lime and cement in every guage. the hydraulic lime based which you have put on the link will breath anyway because of its hydraulic makeup it will naturally absorb carbon dioxide as it cures over time

 

[tommyl18]

regards the breathable paint you can get the one coat renders pre coloured which will save cost of paitning save maintenance and will still let the wall breath i should be a sales rep for them haha

 

[parksy]

Hi Tommy

Thanks for all your comments - sounds interesting.

Does the K Lime take as long to cure as a normal Lime render - ie does it need to be allowed to cure slowly? Do you find it as easy to apply as a cement render?

Also - is the finish smooth or does it have a grainy sandy finish?

By the way - were you suggesting that their other renders are still breathable? Or is it only the K Lime that is?

Chris

 

[tommyl18]

yea the other renders are all breathable because they have polymers in the render which allow it to breath and the lime render will cure like normal lime based render

 

[harleythedog]

K Rend is good, they also do K-Lime for pointing etc: There is Decopierre too, that is coloured on site to your requirements. Pre bagged too. The finish is slightly grity, but made up of limestone, marble and hydraulic lime . Can be sprayed on too.