Dry lining an old farm house

mengele

Is dry lining and insulating an old stone build farm house successfull? Surely if there was a vapour barrier put behind the timbers of the dry lining then it should be successfully?

You need to stop vapour getting behind the plasterboard. If you intend to use insulated plasterboard you need to ensure it is foil backed between the plastboard layer and insulation layer. You then need to seal all seams and all joints to existing walls and ensure all breaches are airtight sealed.

Anything less and you will get black mould behind the dry lining and it will slowly kill you.

Alkers

How old? What is the wall make up and thickness?

mengele

100 to 120 years old i reckon. 2 ft to 3ft thick stone walls. Currently plastered in some lime/cement type mix of plaster.

Alkers

I wouldn't do it

Insulating internally will make the original wall colder than it was previously and also will reduce the wall’s ability to dry out from the inside.

_Brian

we had a specialist out to give advice on our house renovation that’s ongoing. He’s a family friend so lucky to have access to him.

He said nothing on the inside walls that doesn’t breathe. We’re going with 150mm hemp bats, intelligent breathable airtight membrane over that. Boarded and skimmed. He said that was the best compromise between breathability and cost.
he specifically said no foil slabs, no spray foam and no air voids, insulation touching the stone wall all the way.

Another interesting point he mentioned was that the old gypsum skim on the existing walls needs to be removed as of left within the new wall structure it will cause problems.

GrasstoMilk

put a partition around the inside of our house , stepped back off the walls and put 100 mm insulated slab on it. It’s up on 7 years now.

Broke through a door way last year and all looked perfectly dry and no mould that some said would be an issue

148multi

https://www.boards.ie/discussion/2058373046/dry-lining-an-old-farm-house

What's the condition of the walls inside now

mengele

Very Dry at the moment but can get a slight bit dampish on muggy wet winter days but it's more condensation than rising damp. Due to lack of heat in the house as it isn't being lived in.

Wildsurfer

Is external insulation an option or are you exposing stonework? Lime render seems to be the reccomended approach for the internal finish on old stone houses. We dry lined 20 years ago, and it was a great job to kerp house warm but I can't tell you what the condition of the walls are inside the slabs now.

Castlekeeper

There's a great Facebook group called "Cottageology - renovation and appreciation of older Irish homes" with a pile of information links on files as well as links to training courses and workshops on various technical aspects.

The Georgian society and lime builders Forum are also useful networks.

A lot of builders, engineers, and salesmen, talk through their holes on the subject so it can be a minefield initially.

Best of luck with it.

Ours is just lime plastered in and out. Insulation in the floors and roof. Doing very well but if I was doing it now I'd be applying one of the breathable insulated plasters.

Battens and boards can take a lot of space and ruin the character of the house, but if it suits, there are some very good breathable board insulations too.

Most options are very pricey unfortunately but the end result is far better than a new build, imho.

mengele

https://www.boards.ie/discussion/comment/122694898#Comment_122694898

Was the lime plaster very expensive ?

Castlekeeper

Yes, 2 to 4 times the price of standard cement depending on the quotes.

Materials, no. of coats and labour/time.

That's just my experiences.

I don't think breathable insulation is appropriate for old cottages. The original wall surface is going to be the main point of condensation for anything getting into the insulation. You've completely changed the profile of the thermal gradient - created a warm moist air mass internally and only offered it the insulation as a pathway out. Your insulation is going to get saturated and it will run down the surface of the old wall.

A tanking approach to the internal insulation surface seems far more appropriate. Any form of dry lining is suboptimal so you have to work with the limitations of the approach rather than hoping that natural wall drying will somehow be preserved when you have completely changed the behaviour of the structure.

Keep moisture out of the wall as much as possible by addressing any rising damp and then breezes should prevent soaking from the outside accumulating in the old wall.

I am quite open to other approaches, but someone would have to make a compelling case for attempting to preserve breathability in these situations.

Hemp is also hugely expensive in Ireland.

Ak84

https://www.boards.ie/discussion/comment/122695703#Comment_122695703

Would you be in favour of external wall insulation, and lime plaster on the inside. Or even exposed stonework to the inside?

https://www.boards.ie/discussion/comment/122695910#Comment_122695910

External is good but you need access to the wall plate to make it effective otherwise the top of the wall is a huge heat leak - especially in a bungalow.

_Brian

https://www.boards.ie/discussion/comment/122695703#Comment_122695703

I can only pass on what was explained to me..

Your external stone walls will be breathable (in this instance breathable refers to movment of moisture over and back within the wall structure), condensation only happens where there are air gaps. By having the internal insulation snug against the internal wall surface it elimates the air gap, the transition between stone and breathable insulation has noplace for condensation to happen, the breathability of the insulation then allows moisture move into the room as the thouse was originally intended to.

Creating voids, foil boards or plastic components within the new wall structure may cause condensation and hold moisture inside the wall where it cant escape from potentially causing problems..

The house also needs controlled heat recovery ventilation, these old houses partly worked well as the windows and doors didnt seal well and they had large open chimneys, lots of fresh air whether you wanted it or not.. With new materials and closed stoves this creates a need to force ventilation, heat recovery makes sense.. Doesn't have to be a crazy expensive system, perfectly good single room heat recovery ventilation units can be bought from €150 upwards, ours will be €250 a unit as they can work together to provide a better full house ventilation effect..

There are many opinions on this, the chap we had out contributes to government documentatin, consults on historic governmant projects and not that it matters much has been brought onto a number of TV programs both here and in the UK for his expertise on this subject..

bemak

In a similar situation. 2 storey stone farmhouse. a few years ago I gave at trying to remove the existing external sand and cement render but found that it had been rendered 3 times in its lifetime. Removing it was very difficult and efforts would often result in pulling stone out of the wall with lumps of render. In the end i decided that this wasn't a viable option and patched the wall back up.

Following on from that exercise, my current thinking is to install a french drain around the perimeter with surface drains tight to the existing external walls. this should prevent the walls from soaking up water which should eventually resolve the rising damp issues the house is currently experiencing.

I'm also going to reroof the house which will involve taking down the existing chimneys below the roof line and rebuilding them with new flashings. Will install new rainwater goods etc which will tie in with the proposed perimeter drainage.

New windows will happen eventually and then a I'm going to rerender the house with a silicone based render to 'seal' it on the outside and prevent any water ingress via small cracks etc. Given that lime isn't an option for me I think sealing the external side of the wall is the next best thing but I will take the render off the internal face of the external walls at ground floor level to help them dry out to the inside.

Internally I'm going to dig out the existing floor slab and replace it with an insulated slab with UFH. This will give me an opportunity to install a radon sump and bring the DPM up a meter internally on the external walls.

I haven't decided whether I will insulate the walls internally yet or not. I think dry stone walls have better insulating properties than people give them credit for. 'Dry' being the optimum word! So I think I might wait and see what impact the above measures have first before deciding on what to do internally.

There is plenty of information out there and plenty of varying opinions, so I think you have to make the best plan for your own situation. This is mine anyway!

https://www.boards.ie/discussion/comment/122701147#Comment_122701147

I know where you are coming from here, but the flaw in the logic as I see it is that insulation is effectively 80% air with a little bit of fill to maintain the air pockets. There is no part of these breathable insulations that isn't subject to potential condensation because of this. Data is essential to see what is really happening and there is precious little out there.

I fully agree that whatever you do you have to focus on adequate ventilation to keep humidity levels down. We installed whole house MVHR and it's working brilliantly. It has to be factored in at the design stage. Typical whole house DIY install is around €3k.

Also you have to understand your existing walls, our old house had massed concrete walls at 2ft thick and there was no way they were ever going to be breathable so could not be treated with any system that assumed breathability.