Stone built house: Internal dry-line / Lime Hemp plaster / Hemp internal insulation?

Plek Trum

Hoping for experienced advice on this one folks...

Nearing purchase of a structurally sound farmhouse. Walls are approx 2ft deep. Externally, house has been plastered and painted, normal. Internally all stone work is exposed.

3 localised patches of damp that seem to correlate with failed guttering for past few years and large gaps in external path. Our engineer is returning to investigate and confirm.

We will need to insulate the inside of the external walls. People have offered conflicting advice how to do this best.
1) Dry lining / modern internal insulation. Effective and simple, grant available. Others have said this is TOTALLY wrong for stone builds as the stone needs to 'breathe'.

2) Use of hemp products. Far more expensive - huge range of products and conflicting advice on methods of installation and 'layer' required (air membrane, hemp insulation, hemp board, breathable skim, breathable paint finish) Others saying this is not needed as external wall is plastered and water tight?

3) Do old school lime and hemp plaster direct onto the stone work. Will help with insulation, direct approach. Any issues with dampness will be visible , easy to spot. Again, others say not required as external walls of house are plastered.

Does anyone have any experienced advice please??
We want to get this right, do the job once ONLY!

House is in Kerry - any recommendations on specialists you can PM please if thats ok with mods or post here.

Very confused

b.harte

our house is similar.
We ended up going down a sort of hybrid route.
We used 50mm insulated slabs mounted onto a frame work of pressure treated 2x1 over a breathable membrane.
The frame work was secured onto the existing stone using mushroom fasteners.
It wasn't ideal but was the most suitable option as previous owners had used concrete based skim to cover the walls which resulted in some scaring and damp.
We left the house breath for a few months before covering the walls and there are breathing vents dotted around the house.
I know purists might gasp at the idea but it worked out well for us.
It also has the added advantage of have a ready made service cavity for electrics etc. between the slabs and the stonework.
If you have any other questions feel free to ask.
house is toasty during winter and cool during summer / or toasty depending on the "summer" :rolleyes:
One thing to be aware of is the walls will most likely be a lot thicker at the base (makes for fun if drilling for pipes / cables) and may be on shallow (non existent) foundations, we had a problem with one corner where there was effectively no footing, made digging , pouring and insulating the floor a pain and as a result our floor has a crap heat performance. it's the only part we would do differently if we were to do it again.
But, a good engineer will spot all of this.

Plek Trum

Thanks B.Harte - interesting approach! The house is actually fine, upu could move in, plumbed, wired, wooden floors throughout so the groundworks are aren't required (thankfully) Its trying to improve the insulation with the best results thats our aim.

Can I ask was it difficult to install breathing vents in a solid old stone house??

Poor Uncle Tom

Plek Trum wrote: »

Can I ask was it difficult to install breathing vents in a solid old stone house??

I think they mean breathing vents through the insulated slab to the room itself.

b.harte

Poor Uncle Tom wrote: »

I think they mean breathing vents through the insulated slab to the room itself.

A little of both actually. The vents I refered to in my post are indeed vents between the room and space between slabs and wall. We also drilled a few additional holes out through one gable into a lower level shed and these act as vents for the floor space as we opted to use a suspended floor (4x2 on edge) due to the problems encountered with pouring slab. I might put a low pressure vac on these to manage radon as the results are a bit above normal. There are also a few vents at the tops of the walls where the roof sits, but they were there already. Sorry for late reply.

MissSteel

Hi Plek Trum, We are in a similiar position at the moment. We were thinking of using hemp/lime pre-mixed and shuttered on the walls to about 100mm thick. Then use a Hemp/Lime plaster over this. Some of our walls are very off-plumb as a result of the front wall bulging and this approach will allow us to straighten them out. I am hoping that this will leave our house easy to heat and breathable. We contemplated studing the walls and using the insulated slabs but i was nervous if it was done wrong there could be all sorts of mould growth/damage to the stones going on behind and we would never know about it. Also i have heard that the insulated boards lead to the room heating up quickly but looses the heat as soon as the heating is switched off.
We are still undecided, The cost of the insulated slabs is roughly 3 times less than the Hemp/Lime...

Plek Trum

Hi MissSteel - thanks for post.

The one thing I am beginning to realise on this journey is that an old house - done correctly - is going to cost money (and usually more than expected). Modern day solutions will not work on an old house and it has to be treated accordingly.

We are currently getting quotes to remove all external cement render (which is causing internal damp problems) and replaster the house using lime and then a 'breathable' external insulation system. Everything is do-able but at a price. Internally for us, previous owners had exposed the stonework but it was pointed with cement. This will all need to come out and be repointed using lime again.

We might wait and see how the house feels with the new external insulation once done before we cover up the newly repointed internal stonework. Should it need improvement we are going to use a lime / hemp mix, possibly with colour to bring a bit of light to some of the rooms. Again, it is all cost depending!

We have no choice really but to do it right fom day one - OH has asthma and we plan on children so posisble dampness or mould in 10 - 15 years is a no no.

There are great places for advice and direction in Ireland. Try www.traditionallime.com (Carlow) or www.stonewarestudios.com (Youghal)
Both offer introductory courses and I'll be booking a place on one!
We really like the organic finish of the internal insulation, natural sheen and would suit some of the house beautifully. Stoneware studios have colour charts on their website, you should have a look.

We are waiting on quotations for all the above work - we know it wont be cheap and quite possibly shocking but looking at is as a necessity moving forward it is money well spent NOW rather than later. Hopefully it will all work out!

MissSteel

You are so right, it will be worth it in the long run. I have been reading various studys on the effectiveness of the Hemp/Lime and it all seems promising.
We removed the external cement render which was on the house, and are going to replace with Lime plaster. We did it all ourselves with a teleporter and a couple of kango's. What sort of external insulation are you planning on going with?

Plek Trum

Fair play for tackling the work yourselves - did you find it hard? Were hire costs expensive?
Ours is a 2 storey extended property so the idea of tackling it ourselves is a little daunting to be honest but every penny saved.... (!)

We haven't finalised the external insulation as yet - have you any recommendations?

MissSteel

It was hard work! My OH has a teleporter and the kango's so it was just labour costs then for 2 lads to help us. It took just over a week to do it all. It was very hard going, so i dread to think what a contractor would charge to do it, You should possibly look at the costs of hiring the equipment after getting a couple of quotes from contractors, but it all depends on having the time to do it as well.

I dont know of any external insulation as this is not something that we plan to do. We are thinking of a Hemp/Lime scratch coat under the lime dash, this will give a certain level of insulation but nothing major.