Internal wall insulation detail

[thias]

I'm about to start insulating our external walls, internally. I plan to use the "warm batten" method. I.e. sticking PIR to the wall and then mechanically fixing battens through it.

The walls I'm tackling first and back to brick, so far from straight/plumb/even, which is complicating matters. Do I just apply enough spray foam to adhere the PIR straight and plumb and let some long screws through the battens take care of the rest?

What alternative methods would you recommend?

 

[jeds]

Have you considered thermal laminate fixed dot and dab. What thickness of insulation are you trying to achieve?

 

[thias]

Have you considered thermal laminate fixed dot and dab. What thickness of insulation are you trying to achieve?

I have and decided against it. I want to make sure all joints between the PIR boards are well taped etc to avoid the risk of condensation. (Which I consider the biggest risk of installing internal wall insulation on older houses) I also have a couple of pipes to re-route so plan to have a service void between the PIR and the plasterboard.

 

[George_engineer]

What are the battens for? Is it to create a service void and attach plasterboard to? Ideally you would keep the foil intact (and tape the boards) to create a continuous internal vapour control layer. But I don't see why the warm batten method wouldn't work.

Adhesive can be used to level the boards - Charlie DIYte had a good youtube video on how to mark up the floors and ceilings so you keep everything plumb.

Celotex handy guide is worth a look - https://insulation-uk.com/assets/celotex-handy-guide.pdf although they don't show the warm batten approach.

Kingspan and Quinntherm seem to have hidden their details.

 

[jeds]

I have and decided against it. I want to make sure all joints between the PIR boards are well taped etc to avoid the risk of condensation. (Which I consider the biggest risk of installing internal wall insulation on older houses) I also have a couple of pipes to re-route so plan to have a service void between the PIR and the plasterboard.

OK, your choice. Just to note though that I have specified and supervised this method on hundreds of refurbishments over a period of 25 years in just about every type of property you can think of and not once ever had an issue with condensation.

 

[thias]

OK, your choice. Just to note though that I have specified and supervised this method on hundreds of refurbishments over a period of 25 years in just about every type of property you can think of and not once ever had an issue with condensation.

I’ve seen quite a few posts where insulated plaster board has been removed to show rusting back boxes etc all because moist air from within the house has had direct access to the (cold) rear of the insulation. How do you detail around those types of problems?

 

[jeds]

Whichever method you use the mechanics of electrical enclosures means the wall lining will have to be cut out and some degree of vapour will inevitably penetrate to the cold side. But low levels like that are not a problem. For your own project - where you are happy to spend the time and take the extra care - you can take measures to reduce this by additional sealing and if you are in a particularly moist environment you could use stainless enclosures.

 

[thias]

Whichever method you use the mechanics of electrical enclosures means the wall lining will have to be cut out and some degree of vapour will inevitably penetrate to the cold side. But low levels like that are not a problem. For your own project - where you are happy to spend the time and take the extra care - you can take measures to reduce this by additional sealing and if you are in a particularly moist environment you could use stainless enclosures.

Not sure I follow. If the insulation is glued direct to the wall and cables are run down the warm side of it between the insulation and the stud, back boxes etc will always remain "warm" so water vapour won't condensate?