Limelite vs wood fibre boards

[Sauce]

Hi everyone,

Like many here, I live in an old cottage with solid limestone, rubble filled walls. We moved in 5 years ago and are slowly in the process of undoing a fair amount of poor decisions made by previous owners (gypsum plaster and non breathable insulating materials)

So far we've plastered a couple of rooms using lime green products + inset mesh but it has become clear over the past couple of winters that we need to consider installing interior insulation on our external facing walls. I've done a lot of reading over the past few years and have always imagined that we'd use ~40mm cork or wood fibre boards, then skimmed with something like Lime Green solo.

It's been a struggle to reach our old plasterers but finally found someone local who only works with lime and has an impressive portfolio. Upon visiting, he suggested that instead of wood fibre boards, we take the walls back to stone and build up using lime lite renovating plasters to a depth of 40mm which comes in at approx £150 per square metre (labour + materials). I wanted to run a couple of questions by those on this forum who might be able to help give an impartial opinion on this suggestion.

- 1: As I understand it there are mixed opinions on lime lite renovating plasters due to the fact they are not as breathable as other lime based products. So I wonder, does anyone here have experience using lime lite and if so, did you encounter any issues?
- 2: The plasterer suggested that building up lime lite to a depth of approx 40mm would have similar insulating properties to using 40mm wood fibre board, although my research suggests the wood fibre boards would definitely outperform the lime lite plaster in terms of insulation values. I'm always open to listening to people's expertise but worry that the suggestion to build up using lime lite might be based on a preference of materials and ease of use. The plasterer has used wood fibre boards before and said he can go in that direction but lime lite is most definitely he's advised option. Any opinions on this advice he's given?
- 3: Are there any opinions on here as to whether cork or wood fibre are a better option? The wall we'll be doing first is the gable end on the ground floor. Our house is at the bottom of a hill on the end of a row of houses which means we do get the brunt on the water coming down so the wall in question probably is the worst hit part in terms of moisture.

Thanks very much for any advice / suggestions.

 

[Sauce]

Bump. Anyone able to offer advice on this?

 

[a twig]

I suspect the slow response is due to there being a lot of very similar questions regularly asked on here.

Using the search function at the top will give you hundreds of posts in the topic.

Summary is:
Use wood fibre over insulating plasters as the plasters offer very little in the way of performance other than being slightly better than “regular” plasters.

Limelite is better than gypsum, not better than a traditional “fat lime” plaster.

Usually cheaper to mix up your own NHL2 (faster set) or fat lime based (slightly more breathable but more time/care required) insulating plasters (see threads from people like @aockenden ) but most trades just want a simple solution.

Cork vs woodfibre is often a personal preference thing, many here have had excellent results with both systems

 

[Sauce]

I suspect the slow response is due to there being a lot of very similar questions regularly asked on here.

Using the search function at the top will give you hundreds of posts in the topic.

Summary is:
Use wood fibre over insulating plasters as the plasters offer very little in the way of performance other than being slightly better than “regular” plasters.

Limelite is better than gypsum, not better than a traditional “fat lime” plaster.

Usually cheaper to mix up your own NHL2 (faster set) or fat lime based (slightly more breathable but more time/care required) insulating plasters (see threads from people like @aockenden ) but most trades just want a simple solution.

Cork vs woodfibre is often a personal preference thing, many here have had excellent results with both systems

Twig, thanks very much for taking the time to reply despite the questions being commonly asked - This website has been a great resource for me and I suspected these answers would be the general consensus though I think it's one of those things where a bit of confirmation in relation to my specific questions goes a long way to providing the reassurance I need to move forward. Insulation boards it is - part of the attraction for me is not just the improved thermal performance but also the fact I'd likely be able to fit these myself in order to reduce the overall cost. Though when I suggested this to the plasterer he was keen to remind me that the wall may need to be levelled with a base coat before the wood fibre boards go on. In that case might still manage it myself - possibly using the 'screeds' method. Thanks again!

 

[a twig]

Lists of useful information in this thread covering both wood wool and wood fibre insulation options and installation methods with photos etc

 

[jamest]

I wouldn't use Limelite renovating plaster. It's hard to find the details, but it would seem that it is a lime-cement plaster, not a true lime plaster. Limelite quote a water vapour diffusion coeffiecient of 12.22 for their renovation plaster, which is within the range expected for a lime-cement plaster, but not nearly as good as a lime-only plaster (which is typically between 6 and 8).

I've used the seciltek system that A Twig used and it's easy to do - you could DIY a parge coat to flatten the wall, stick cork or wood fibre board over the top (internally no fixings are needed, you can just stick it on with lime plaster). Then get your plasterer to skim over it if you're not happy with the kind of final finish you can get yourself. Personally, I kind of like the rustic finish I end up with, but you need the right kind of house, I guess.

 

[Sauce]

I wouldn't use Limelite renovating plaster. It's hard to find the details, but it would seem that it is a lime-cement plaster, not a true lime plaster. Limelite quote a water vapour diffusion coeffiecient of 12.22 for their renovation plaster, which is within the range expected for a lime-cement plaster, but not nearly as good as a lime-only plaster (which is typically between 6 and 8).

I've used the seciltek system that A Twig used and it's easy to do - you could DIY a parge coat to flatten the wall, stick cork or wood fibre board over the top (internally no fixings are needed, you can just stick it on with lime plaster). Then get your plasterer to skim over it if you're not happy with the kind of final finish you can get yourself. Personally, I kind of like the rustic finish I end up with, but you need the right kind of house, I guess.

Thanks James. I've taken yours and Twig's advice and now have a quote for materials. Spoke yesterday with our plasterer who has also been really helpful with advice for the install of the boards and flexible with which plastering materials he's able to work with. Likely going to move forward with all materials ordered from Mike Wye. Thanks again for taking the time to reply

 

[Kearn]

Thanks James. I've taken yours and Twig's advice and now have a quote for materials. Spoke yesterday with our plasterer who has also been really helpful with advice for the install of the boards and flexible with which plastering materials he's able to work with. Likely going to move forward with all materials ordered from Mike Wye. Thanks again for taking the time to reply

Shop around, not all prices are equal. I’ve found MW more expensive than Ty Mwar, but over the past year I’ve exclusively used Eden - initially on cost, but over time the relationship has helped. Others talk highly of Cornish also.