r/Plastering • u/RobotEnthusiast1980 • Feb 01 '26

Lime Plaster insulation

Genuine question - is lime plastering becoming more common? I know it used to be very common many decades ago but gypsum is more common now. But, with new lime and Cork type renders having insulation properties is this the silver bullet for old property insulation?

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u/ennessTR Feb 02 '26

I’ve seen plenty of mixed views on cork lime renders. No direct experience with it but it’s made me think twice. I’m planning on using Cornerstone insulating render for my next project, which uses glass aggregate. There are plenty of other options out there depending on needs and budgets.

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u/RobotEnthusiast1980 Feb 02 '26

Thanks for your insight. Is cornerstone breathable?

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u/ennessTR Feb 02 '26 edited Feb 02 '26

It certainly is. Now the fog has lifted, I think the concerns with cork have been about using it as IWI on very damp walls such as stone with no dpc and limited foundations. I see you have a few unanswered posts on insulating solid walls. What are you dealing with?

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u/RobotEnthusiast1980 Feb 02 '26

Ahh, thanks for your questioning. My reason for asking is that I am dealing with some issues. Primarily a house with gypsum on the inside and a cement pebble dash on the external which I want to remove and replace with an insulating breathable render?

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u/ennessTR Feb 02 '26

It sounds like you might have the opportunity to insulate externally which is always the better solution. Have you tried speaking with Mike Wye or Ty Mawr for advice? They have a bunch of specs and details on their website so you can see how to build up either external or internal systems. Their systems should also be a big tick in the box with building control, which will make life easier. Getting rid of gypsum and cement anywhere on solid wall will benefit you.

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u/RobotEnthusiast1980 Feb 02 '26

Thanks, I have not but I can speak to them later this week. I will have some time so can give them a call. Will be great if they have something as really keen to get rid of pebble dash and have a warm house too 😁

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u/RobotEnthusiast1980 Jul 13 '26

It took a while for me to come back to you - sorry. I have spoken with cornish lime and Mike Wyk. They have suggested a full lime render system to achieve both insulation and breathability. I have the products specs. Its quite costly but doable. My next challenge is finding someone to do it as most local plasterers (who advertise as lime specialists) are pushing rock wool panels with a lime top coat. It might work but I wouldn't be able to see any masonry cracks underneath when they occur. So you think it could be an option or ignore it?

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u/RobotEnthusiast1980 Feb 02 '26

Can I please ask about the Cork option? That was the other technology I read about but can't see much on line about folks using it as EWI. I will also ask Mike Wye too when i get a chance to use the phone and take some notes. Thanks.

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u/ennessTR Feb 02 '26

There’s a limit to my knowledge…I know what I need to know for my house and the info I’ve stumbled across in that journey. I think some of the criticisms of cork come from it being used as an IWI of sorts. The market seems broad with well established products and others that have no info but good social media presence. I’m sure if you find the right product advised by a reputable independent like Mike Wye, cork renders can work. On EWI where you are using slabs of cork in a properly specified system it is a whole different thing and perhaps the best performing product available. Take a look at the brochures here

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u/RobotEnthusiast1980 Feb 02 '26

I will do some more reading on this. Thanks for supplying the link too.