Insulated render - anyone used?

K

Kaymo

New Member
Hi all,
First post, not a plasterer (couldn't plaster a flat surface of more than an inch to save my life) but hopeful that this is the place to get some info and maybe even some local contacts!

I have recently bought an old Sandstone house, that has had cement based render/harling applied to the back and sides presumably in the eighties. Its boss and cracked in places and I want to replace it with a lime based, breathable render. I would ideally like this to be an insulated render but haven't been able to find anyone who has actually used it.

There appear to be a number of brands out there, Bauwer, Baumit, and my current front runner Diathonite evolution. Seems ideal for my situation, where I probably wouldn't get planning for EWI, but would probably get away with around 30mm of render, which I have calculated would lower the U value from about 2.3, to about 1.

Has anyone out there used it, or heard any feedback from others who have used it?

Also, anyone in the central Scotland area that would be interested in applying it?

Thanks
 
You might get away with ewi, it's worth a punt, you improving on the u values, you need planning anyways if it's over 25% to be covered
 
I was told that a bag of Diathonite was around £35. I worked out the price compared to Bauwer and a few others per square meter based on an equivalent thermal resistance and its was slightly more expensive. The advantage it has is I can get a higher thermal resistance, and thus better U value, for the same thickness, and as I am restricted on thickness then that is an advantage.

I should be clear that I am referring to an insulated render product that is wet applied as opposed to EWI with render on top. EWI is not ideal on the sides because the only overhang is coping stones on the roof, it couldn't be put on thick enough to be worthwhile. The front needs to remain uncovered Ashlar block sandstone as its in a conservation area so anything more than a thin layer of insulated render would look out of place and fail at the planning stage. If I keep the render thin and similar in appearance to the current render I might be able to avoid planning completely, or at least make it easier to pass.

I asked Bauwer before and they didn't have anyone using it in Scotland.

I think its worth doing, possibly only £500 or so above what I would be paying anyway to get it done in lime based render, and dropping the U value from 2.3 to 1. I would obviously want to lower it further with internal insulation, but this would reduce the thickness I need on the inside and probably help with reducing thermal bridges and interstitial condensation.
 
Kaymo said:
I was told that a bag of Diathonite was around £35. I worked out the price compared to Bauwer and a few others per square meter based on an equivalent thermal resistance and its was slightly more expensive. The advantage it has is I can get a higher thermal resistance, and thus better U value, for the same thickness, and as I am restricted on thickness then that is an advantage.

I should be clear that I am referring to an insulated render product that is wet applied as opposed to EWI with render on top. EWI is not ideal on the sides because the only overhang is coping stones on the roof, it couldn't be put on thick enough to be worthwhile. The front needs to remain uncovered Ashlar block sandstone as its in a conservation area so anything more than a thin layer of insulated render would look out of place and fail at the planning stage. If I keep the render thin and similar in appearance to the current render I might be able to avoid planning completely, or at least make it easier to pass.

I asked Bauwer before and they didn't have anyone using it in Scotland.

I think its worth doing, possibly only £500 or so above what I would be paying anyway to get it done in lime based render, and dropping the U value from 2.3 to 1. I would obviously want to lower it further with internal insulation, but this would reduce the thickness I need on the inside and probably help with reducing thermal bridges and interstitial condensation.
Click to expand...
 
Have you though of using a lime/hemp exterior render?
Not sure what the u-value would be, but we have applied to old houses effectively as a ewi equivalent.
 
JVplastering said:
Have you though of using a lime/hemp exterior render?
Not sure what the u-value would be, but we have applied to old houses effectively as a ewi equivalent.
Click to expand...

Thanks JV, I did a search for lime hemp plaster but the makers were not publishing the thermal conductivity or resistance, only saying that it had "some thermal properties". I found one supplier stating that hemp lime plaster had a thermal conductivity of 0.07-0.09 W/mK.

The Diathonite Evolution is 0.045 so its still the best insulator for the thickness I can find. It appears to be cork and diatomaceous earth that are the insulators in this.
 
We were supposed to use Diathonite on a job last year but the client/architect ended up changing their mind at the last minute for whatever reason. Had trouble finding out about it from anyone who used it but finally managed to get in touch with a company down south who used it and they said it was a pig to use and aesthetically really wasn't up to much so we were quite happy to have missed out on the chance to use it in the end.
 
Thanks GrantyBoy. I'll admit I am a bit nervous about this product. On paper it looks great, but if it isn't applied right, or looks crap in the finish, then it could be a lot of money spent for...
 
Spot on Kaymo, try and find a job it's been used on because it's a lot of dough for what could look like a dogs dinner on your nice gaff.
 
Every render is slightly different than the other, but similar to another.My point is f you have experience there shouldn't be a problem. Lime is difficult and hard work to get right in a first place. Timing is everything, just like when I used Bauwer light for first time when is wet you can rule it and flatten it, 5 mins later you can't touch it, 30-40 mins later you can even scrape it. Said it before Bauwer light is very good product. You should put it on your list tbh.And I'll be reluctant to use hemp lime for external render.
 
Thanks vfr12 - Bauwer was the first product I looked at, but the diathonite had a better thermal conductivity which is why I was focussing on that. I'm not a plasterer, and its not something I would be any good at even if I took my time, so I would need to get someone to do it. The Mason I have working on the house wasn't keen on it and I couldn't find anyone else locally so for the moment I have just decided to get it back to the original stone and pointed. Might consider it again in the future but there were lots of other complications, not least the fact that I am in a conservation area and would need a planning application to do it.

Thanks Dmitrijs, they don't have insulated render but thanks for the link anyway.
 
Yes, plan to do that at some point. But internal insulation is tricky, especially on an old house. Can risk interstitial condensation so I need to think it through, and there are difficulties with old features such as cornices etc, that would restrict the thickness etc.

There is a product called aerogel that has a very low conductivity but is flexible and breathable, and can go straight on to the wall then plastered over, so ideal for old houses, but still ridiculously expensive. No easy answers here, so I am concentrating on the modern extension at the back, as this is a bit easier, while I think through the old house.
 
Kaymo said:
Thanks vfr12 - Bauwer was the first product I looked at, but the diathonite had a better thermal conductivity which is why I was focussing on that. I'm not a plasterer, and its not something I would be any good at even if I took my time, so I would need to get someone to do it. The Mason I have working on the house wasn't keen on it and I couldn't find anyone else locally so for the moment I have just decided to get it back to the original stone and pointed. Might consider it again in the future but there were lots of other complications, not least the fact that I am in a conservation area and would need a planning application to do it.

Thanks Dmitrijs, they don't have insulated render but thanks for the link anyway.
Click to expand...

Yes they do have insulated render , i deal with them on daily basis :)
 
I took a look at the website yesterday and couldn't see any, either under insulation, or render. What brands to they have?
 
I think you might have misunderstood what I meant by insulated render. I think you are talking about EWI that is rendered over. This thread was about render with a low thermal conductivity so that the render itself does the insulating. Diathonite evolution, Bauwer lite etc.

EPS and Rockwool are not recommended on old solid stone wall houses such as mine as the walls. The benefit of the renders I have mentioned is that they have low thermal conductivity, approaching that of EPS, and a high vapour permeability.
 
Kaymo
Check K Rends new range of Heritage lime renders and this Hemp lime binder
Could be the answer
 

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Just read through this post, dont know if of any use now.
I have used Diathonite evolution, one bag only. It is made of cork and clay.

One house i have seen it applied externally and one flat applied it both internally and externally.

It is interesting product, just equivalent to any other insulation product on the market.
It is labor intensive to install it. Has very large grain size of cork. All materials, this product is based on, are natural, which i see as plus only when used internally. Also moisture absorbing feature, may make it suitable for some applications where it is desired.
 
Kaymo said:
Hi all,
First post, not a plasterer (couldn't plaster a flat surface of more than an inch to save my life) but hopeful that this is the place to get some info and maybe even some local contacts!

I have recently bought an old Sandstone house, that has had cement based render/harling applied to the back and sides presumably in the eighties. Its boss and cracked in places and I want to replace it with a lime based, breathable render. I would ideally like this to be an insulated render but haven't been able to find anyone who has actually used it.

There appear to be a number of brands out there, Bauwer, Baumit, and my current front runner Diathonite evolution. Seems ideal for my situation, where I probably wouldn't get planning for EWI, but would probably get away with around 30mm of render, which I have calculated would lower the U value from about 2.3, to about 1.

Has anyone out there used it, or heard any feedback from others who have used it?

Also, anyone in the central Scotland area that would be interested in applying it?

Thanks
Click to expand...
ProofTherm Insulating Render
 
The above sounds on par with Bauwer and Diathonite. I have used Bauwer internally and it has worked. Well. If it is for outside you will need someone who knows how to apply. It can be labour intensive but an experienced gang with a machine will be better. Let it fully cure before you apply top finishing coats.
 
Check out the Green Building Forum, plenty of people have used both products. Generally they have a good reputation for being nicely workable.
 
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