Internal Vapour Control Layer for Stone Cottage?

Bluscreendream

Hi all,

Just looking for some advice. I'm working on a stone cottage from the 1750s. At present I'm looking to insulate the main bedroom. As the walls are stone, about 70cm thick, there is no cavity, so my plan is to use steel studding placed about 7cm in from the stone wall, with fixed insulation placed in the frame. My concern is that mould or condensation would build up on the internal face of the stone wall and so I've been looking into Vapour Control Layer or Barrier type products.

There seems to be two systems, moisture-open insulation or moisture closed, there is a tonne of conflicting views on which systems to employ and as I'm not a builder, I'd greatly appreciate any advise on which product on the Irish marker would work in my particular situation. I've attached a sketch of what I'm trying to achieve which might explain my setup better. Any input or ideas would be really

appreciated.

many thanks,

B

MicktheMan

So, you have a cement render to the inside of the stone wall and a concrete render to the outside? On a 1750's cottage??

This is where I would start with any reno. I suggest that those renders are the first issue(s) to address.

TimHorton

https://www.boards.ie/discussion/2058374009/internal-vapour-control-layer-for-stone-cottage

This couple dealing with the same task….https://youtu.be/GH4Fzl1d428?t=865

Lumen

I don't think it's possible to recommend a solution without surveying the property. Lots of factors may be important: climate, aspect, site topology, land drainage, proximity of soil and vegetation, quality of exterior render, guttering and downpipes, number of storeys, whether the property is continuously occupied etc. Plus aesthetics and budget.

There's a decent Cottageology FB group where you can find examples of different approaches in various locations. If nothing else you'll be able to see what each approach looks like when finished. It's quite DIY-focused though, i.e. people doing stuff themselves on a tight budget, and making mistakes.

Calahonda52

Good luck with this project

[there is a tonne of conflicting views ] arises only because you have folk who know < = SFA about the physics, who have access to the internet and …….

Iff the killspan is alu sided and joints are taped the the VCL is a waste of money as the alu is 100% impermeable

a few starter questions

1: is there a DPC in the floor? M assuming none in wall

2: whats the rest of the reno plan: it's key that reno is holistic so as u don't end up with mistakes re building physics

3: what thickness of insulation have you in mind?

3a: what services will be embedded in the wall

4: what impact will it have on internal room sizes?

5: how are you dealing with thermal bridging for internal walls that join the external wall?

6: Have you considered EWI?

7: How exposed in the site to driving rain?

8: Any French drain around the house to reduce water table impact on floor/walls

9: What's the plan for attic insulation?

10 What the ventilation strategy?

As a mark of respect to those who died in the Grenfell inferno, I will never ever use/specify a Kingspan product

27cyrix

I recommend reading the PDF in this link. (wall section)

gov.ie - Improving Energy Efficiency in Traditional Buildings, Guidance for Specifiers and Installers, 2023 (www.gov.ie)

Bluscreendream

https://www.boards.ie/discussion/comment/122712749#Comment_122712749

Hi Mick, thanks for the reply. In a perfect world the renders would be removed and Lime rendering applied but logistically and financially it's not realistic for me, the external concrete render is an inch thick in some parts I've checked and is extremely strong. I'm just seeing if there are any ways I can approach this problem from inside the room with the current factors.

Bluscreendream

https://www.boards.ie/discussion/comment/122713732#Comment_122713732

Thanks Tim, very informative and he also has a trove of other videos which will be of immense help to me, nice find!

Bluscreendream

https://www.boards.ie/discussion/comment/122713935#Comment_122713935

This is true, there are so many factors at play. Thanks for FB recommendation, extremely useful. I'm a DIYer on a budget so it's great to see other people in the same situation finding the best practical solutions can.

Bluscreendream

https://www.boards.ie/discussion/comment/122718122#Comment_122718122

This look interesting 😁Excellent, thank you!

Bluscreendream

https://www.boards.ie/discussion/comment/122713955#Comment_122713955

Hi Calahonda,

Thank you! I've answered your questions the best I can and in doing so will reveal how much I'm winging this project. Interesting point… I never thought of that, 😄Yes the fixed insulation would be alu backed and I normally tape all joints with the foil tape.

1: is there a DPC in the floor? M assuming none in wall

Yes there is.

2: whats the rest of the reno plan: it's key that reno is holisticso as u don't end up with mistakes re building physics

The remaining rooms have the same setup, cement render inside and concrete render outside.

3: what thickness of insulation have you in mind?

I would be happy with 30mm but I was thinking, if I used framing system I could insert 4 to 5cm within the frame.

3a: what services will be embedded in the wall

Electrical sockets, switches and cabling

4: what impact will it have on internal room sizes?

Even with the gap between the framing and stone wall, the remaining internal room size is ample, I have no complaints here.

5: how are you dealing with thermal bridging for internal wallsthat join the external wall?

This is were things get murky, it’s very difficult to put this into writing, a lot of factors at play

6: Have you considered EWI?

For a minute, but roof overhang limitations, soffit and facia restrictions have ruled this option out.

7: How exposed in the site to driving rain?

Very much exposed!

8: Any French drain around the house to reduce water table impacton floor/walls

Early next spring I will be addressing this.

9: What's the plan for attic insulation?

Roofing insulation is completed.

10 What the ventilation strategy?

There are no vents in any of the walls

As a mark of respect to those who died in the Grenfell inferno, Iwill never ever use/specify a Kingspan product I would agree with youthere. The reference to Kingspan was a poor choice of words on mybehalf.

I will never buy their products again. I have this terrible habit of using Kingspan as a general term for ‘fixed insulation’, actually I’ve only used Ballytherm so far on this building.

many thanks,

B