lime plaster idea!

[plasticpigeon]

After having yet another unsatisfactory experience of a tradesman, this time a plasterer, who was a thoroughly nice guy but not a careful worker, I have decided to do everything myself, as I always end up redoing most stuff carelessly done by my ill chosen tradesmen anyway. The next big job is lime plastering the kitchen. I have given this quite some thought and for convenience I am going to use hydraulic lime. I think the general consensus is to use a 2:1 mix with sharp sand for the backing coats and then 1:1 with plastering sand for the skim. I was wondering if anyone had used vermiculite in the backing coats instead of sand. It would be lighter and easier to apply (I'd have thought) and would also have more insulating properties than sand. Also Telling lime make a plastering product that is very expensive that is just a vermiculite NHL mix so it must be a possibility. Unless it is very silly for some reason, I think I will experiment and try it.

In fact could it also be used for screeding under a quarry tile floor??? I understand that it might be a bit weak for a floor but what do people think???

Many thanks.

 

[Gervase]

After having yet another unsatisfactory experience of a tradesman, this time a plasterer, who was a thoroughly nice guy but not a careful worker, I have decided to do everything myself, as I always end up redoing most stuff carelessly done by my ill chosen tradesmen anyway. The next big job is lime plastering the kitchen. I have given this quite some thought and for convenience I am going to use hydraulic lime. I think the general consensus is to use a 2:1 mix with sharp sand for the backing coats and then 1:1 with plastering sand for the skim. I was wondering if anyone had used vermiculite in the backing coats instead of sand. It would be lighter and easier to apply (I'd have thought) and would also have more insulating properties than sand. Also Telling lime make a plastering product that is very expensive that is just a vermiculite NHL mix so it must be a possibility. Unless it is very silly for some reason, I think I will experiment and try it.

In fact could it also be used for screeding under a quarry tile floor??? I understand that it might be a bit weak for a floor but what do people think???

Many thanks.

Hmm (sucks teeth and thinks about heading up the M6...)
2:1 is a bit rich; aim for 2.5:1 max, or you may get cracking. As for vermiculite, what about hemp shiv; far more insulating, I've never worked with vermiculite but, more to the point, nor have any of the other lime plasterers I've worked with (and there are quite a few). My thinking is, if it's good, some loon must have done it before, and I know of no such loon! But, if you've the time, the money and the square footage, experiment.

 

[plasticpigeon]

Hello Gervase, thanks for the tip. The strength of the mix was just what I had gleaned from data sheets from manufacturers like st Astier and Roundtower. What mix would you use in the top coat, would you use 2.5 to 1 there as well? Here is a link to a commercial company selling lime perlite plaster which is what gave me the idea. It is called Unilit 20.

http://telling.co.uk/telling-lime/hydraulic-lime/technical-data/

I know vermiculite can be got quite cheaply from people who parge chimneys so thought it might be a cheap alternative. I'm guessing the hemp can be got from eco building suppliers. I shall look into it.

many thanks

 

[TheForge]

The best option for hemp is to buy direct from the farmer, it's about half of the price you'll pay from an Eco Building supplier. (Or you can buy hemp horse bedding - but I'm not sure the quality would be the same!)

You need a licence to grow hemp commercially in the UK so supply is limited but we got ours from the Voase family in Yorkshire, they supply both coarse (for backing coats) and fine for finishing coats. Although you might want to use just lime and silver sand to get the best finish. If you search the web for Voase hemp you should find their number.

Although hemp shiv is good insulator you need to put it on pretty thick to achieve any serious u-value! (I've heard around 10cm!). Theres also a debate about whether it will rot out in permenantly damp conditions but it seems ok where we've used it.

 

[garnett]

Hello

Myself and a group of other conservation officers were shown a new product that may be what you are after. With the demise of cork in favour of screw tops the Portuguese have been looking at new uses for cork. They have produce a cork and lime mixture which has fabulous insulating properties, breathes and is very light to work with. Even we could plaster with it which is saying something!

It is being imported by a lime specialist in North Devon, but others may be offering it as well.

Good luck.

Garnett

 

[stuart45]

I've seen vermiculite mixed with cement render in Germany, but I don't think the insulating qualitiess are that good. It's more usefull in places like window reveals where it just tips the balance enough to keep the surface above dew point and avoid condensation.

 

[andrew gayton]

H Y D R A U L I C lime for plaster/render?? :shock: