Granite House Insulation

Lycian

I have recently purchased a granite house and I am looking for the best way of insulation the walls internally. I come across with a few ideas, I am just wondering which one is the "best". I it can be quite relative, but I am sure there are technics that should not used and there are ones that are better.
Current ways I come across:

• Filling cavity with expanding foam - full No No
• Cavity, L2L, Cavity, Rock wool (or any other wool insulation) - seems like a good idea up for a depate
• Lime plaster mixed with hemp directly to the granite wall - this used on historical building in Scotland - Sounds OK for me, maybe extra plaster boards for nicer finish?
• Build a stud wall leaving an air gap between the external wall & any insulation. Use rigid rockwool batts, and finish off with a wood wool board - Plaster with lime to retain breathability of the walls. Don't bother with wool - It may well attract wool moths and has a limited life - From FreeBear

I will try to expand this list when we get more comments so new readers do not need to read the full thread. Any idea is welcomed!

Furts

I am assuming you have cavity walls, since you mention cavity insulation. But do you? Cavity walls, and hemp insulation do not normally go in the same sentence, nor does historical buildings.


Which means clarity from you here. But if you are considering cavity insulation then a competent, professional survey is an absolute must.


You mention Scotland and here you need to be very careful. It can be wet and exposed there.

FreeBear

A work colleague refurbished her cottage and used hemp plaster - From what she was saying, I don't think she was impressed with it in terms of insulation.


As per post above, are you sure it is a cavity wall ?
I would look at building a stud wall leaving an air gap between the external wall & any insulation. Use rigid rockwool batts, and finish off with a wood wool board - Plaster with lime to retain breathability of the walls. Don't bother with wool - It may well attract wool moths and has a limited life.


If it really is a cavity wall, then have a look at "warm battens" with Celotex/Kingspan insulation boards. But you need to consider any potential areas where damp may form and take measures to prevent it from happening.

J_B

What's a 'granite house'?

Lycian

Furts wrote: »

I am assuming you have cavity walls, since you mention cavity insulation. But do you? Cavity walls, and hemp insulation do not normally go in the same sentence, nor does historical buildings.


Which means clarity from you here. But if you are considering cavity insulation then a competent, professional survey is an absolute must.


You mention Scotland and here you need to be very careful. It can be wet and exposed there.

Sorry if I was not clear. In this post I want to list option for granite house internal insulation, I did not say that I have any of them.
I would like to collect the best practice options.
My move in date is next week, so I can clarify 100% what it is there right now, but I assume it is cavity wall.

Lycian

FreeBear wrote: »

A work colleague refurbished her cottage and used hemp plaster - From what she was saying, I don't think she was impressed with it in terms of insulation.


As per post above, are you sure it is a cavity wall ?
I would look at building a stud wall leaving an air gap between the external wall & any insulation. Use rigid rockwool batts, and finish off with a wood wool board - Plaster with lime to retain breathability of the walls. Don't bother with wool - It may well attract wool moths and has a limited life.


If it really is a cavity wall, then have a look at "warm battens" with Celotex/Kingspan insulation boards. But you need to consider any potential areas where damp may form and take measures to prevent it from happening.

I will use insulation boards for the floor, but I have been advised that insulation boards could "sweet" if I use them for the walls. I am not sure, I am still far from drawing proper conclusions.
Thank you for the idea, I will confirm my current structure and add your idea to the original post.

Lycian

J_B wrote: »

What's a 'granite house'?

A house built with granite external walls.

Lycian

Regarding a professional surveyor; I was going to get in a few different professionals to provide me quotes and possibilities, but in the meantime I would like to educate myself as much as possible - as many surveyors/builders as many possibilities there are.

Furts

Lycian wrote: »

Regarding a professional surveyor; I was going to get in a few different professionals to provide me quotes and possibilities, but in the meantime I would like to educate myself as much as possible - as many surveyors/builders as many possibilities there are.

Not much anybody can add until they know your wall construction. Cavity or solid? Depending on this there are three routes - internal, external and cavity wall insulation. All are completely different and all have pros and cons. Until more is known such as altitude, frost, rainfall, exposure, aesthetics, Conservation Area, Planning .. the list goes on it is impossible to say.

Lycian

Apologise, I had some misconceptions about cavity walls. I'm still guessing here, but I think my external walls are 500-600mm granite, then wood studs and plater boards, probably some insulation. So my questions aims for insulating pure granite external walls

System

This gives a good overview of your options https://www.historicenvironment.scot/archives-and-research/publications/publication/?publicationId=179c1909-3679-4486-9583-a59100fa98c1