Fine tuning my IWI Solid wall (Warm Batten) design

[Redbeard]

1 hour ago, Iceverge said:

Maybe @Redbeard has more experience than me. 

 

Hello! Not with mineral wool, I am afraid. I have not used mineral wool as an internal insulant. I think I would be a little uncomfortable using it without a VCL, as even the 'rigid' grade of rockwool used for EWI is not as dense as 'basic' (140kg/m3 - 180kg/m3) rigid WF in terms of moisture-buffering ability, although at apparently 110kg/m3 it's not so far away). If you are finishing with plasterboard you could (at a cost) use an intelligent membrane such as Pro Clima's 'Intello'.

 

Yes, for reveals use as much insulation as you can get in without 'losing' the window or door frame.

 

If you were taking the risk of no VCL then you could buy the EWI grade of rockwool and plaster directly to it, with the necessary mesh reinforcement, effectively as per thin-coat EWI.

[torre]

On 15/10/2024 at 13:18, ab12 said:

some sort of ventilation system put into the property... PIV or decentralised MHRV etc

I would avoid relying mostly on PIV in an old property and use MVHR or continuous DMEV instead.

 

If there's a lot of moisture internally, PIV has to push that out somewhere, and that's likely to be into any gaps etc, where it may condense, potentially making any damp problem worse, whereas MVHR or continuous extract will help ensure more of the moist air is pulled out of the property.

[lookseehear]

23 hours ago, Redbeard said:

 

Hello! Not with mineral wool, I am afraid. I have not used mineral wool as an internal insulant. I think I would be a little uncomfortable using it without a VCL, as even the 'rigid' grade of rockwool used for EWI is not as dense as 'basic' (140kg/m3 - 180kg/m3) rigid WF in terms of moisture-buffering ability, although at apparently 110kg/m3 it's not so far away). If you are finishing with plasterboard you could (at a cost) use an intelligent membrane such as Pro Clima's 'Intello'.

 

Yes, for reveals use as much insulation as you can get in without 'losing' the window or door frame.

 

If you were taking the risk of no VCL then you could buy the EWI grade of rockwool and plaster directly to it, with the necessary mesh reinforcement, effectively as per thin-coat EWI.

 

Thanks for this. What attracted me to the method of parge for airtightness and rockwool/service void/plasterboard finish is that it decouples the airtightness from the services (no taping socket backboxes etc). It seems simpler from an execution perspective and I think this would work well with our builder and help me stay on top of the quality of the work. It isn't that I don't think he'll do a good job, but I think that we still have work to do when it comes to selling the importance of airtightness. I'm also wary that the more rigid the insulation board is, the less able it will be to match the uneven shape of the stone walls, and the more likely we are to have voids.

 

If we were to use a parge coat of NHL 3.5, rockwool within a CLS timber 'batten' frame, Intello Membrane then Plasterboard (and I assume a skim of gypsum), does that mean that all sockets/holes need to be taped to the Intello membrane?

 

Our project is a combination of extension, reorganisation and renovation, so anywhere we can create a simple solution will be big positive.

[lookseehear]

On 27/10/2024 at 13:49, torre said:

I would avoid relying mostly on PIV in an old property and use MVHR or continuous DMEV instead.

 

If there's a lot of moisture internally, PIV has to push that out somewhere, and that's likely to be into any gaps etc, where it may condense, potentially making any damp problem worse, whereas MVHR or continuous extract will help ensure more of the moist air is pulled out of the property.

 

Thanks for this - I think we're likely to use a combination of centralised and decentralised MVHR, as we can likely get ducting to 2/3 of the house relatively easily, but the final 1/3 will be more tricky. This definitely makes sense to me.

[Redbeard]

6 hours ago, lookseehear said:

If we were to use a parge coat of NHL 3.5, rockwool within a CLS timber 'batten' frame, Intello Membrane then Plasterboard (and I assume a skim of gypsum), does that mean that all sockets/holes need to be taped to the Intello membrane?

How about the above but with added 25 x 38 (?) counter-battens over the Intello, forming a service void so that the elecs are inside the air-tightness/VC layer?