Lime Plaster

[gbbuggydriver]

Hi

I've got an old house with solid walls (no cavities) which has been badly rendered with cement and aggregate. Had someone round who said knock it all off and put lime render back on because it helps the building breathe. But this will take longer and cost more. I have'nt heard of buildings having to breath before - what's he on about? Should I shell out more for the lime render or go for an ordinary render?

Cheers

 

[Mick Leek]

Well i have just done mine. Not used a FULL lime render as its a skill on its own to do but i have added lime to the cement agregate mix..

I think he may mean this way. The lime does help with preventing cracks in the finish and also allows to breath, very important..

Whats wrong with the other finish ? just a bit crappy looking or is it falling off ?

Mick

 

[gbbuggydriver]

Thanks for your reply Mick

It's a bit rubbishy looking but there are also cracks in places and a few chunks coming off. It smells a bit damp inside the house although not obvious where it's coming from. Not sure whether it's best just to seal the cracks up to stop the damp getting in if that is where it's getting in or go for the full lime render 'breathing' route. How much difference is there between Lime and ordinary render? Any more opinions/advice gratefully received!

 

[PatrickD]

The difference between lime render and cement based render is like chalk and cheese and it's difficult to know where to begin.

If your walls are solid then putting any render with cement in it is likely to cause you problems in the future. These problems arise because cement will not allow evaporation of moisture from the inside and also, as the cement cracks (as it surely will do), water will get behind the render and can't get out again. You can imagine the effect this will have on your walls. Lime mortar is permeable and, to a degree, self repairing should it crack.

Now is the time of year to render the buidling if you're using lime and ideally you should use a non hydraulic mix or, at worst, a feebly hydraulic mix (others will probably have differing opinions).

You need someone who knows what he's doing and if you visit lime.org.uk, or Mike Wye's site, you'll probably be able to find someone who can help you.

Yes, it will cost more, but in the long run it'll be worth it. Just think of the lovely finishes you can get on it with a limewash afterwards!

HTH

Patrick

 

[MerMer]

Ideally you shouldn't add Concrete to the Lime render because there is a danger of the two segregating and then the render will eventually fail. Most companies would recommend a type of Pozzolan instead, in order to give the lime render slightly more strength.

There is now alot of information on the web on this. A good starting point is www.mikewye.co.uk

 

[Nige F]

you beat me to www.mikewye Haven`t heard of pozzolan

 

[JohnD]

you beat me to www.mikewye Haven`t heard of pozzolan

roman cement? (volcanic)

 

[fitz1]

dont forget the horse hair to bond the lime mortar.