Insulating a solid brick wall

[Marvin]

Please can you tell me what the best way is to approach insulating an old 2 up 2 down solid brick wall house external walls.

Slap a coat of PIR on the plaster?

Seal the wall first?

Batten out?

Strip plaster?

Insulated plasterboard?

Help, thoughts appreciated.

 

Thanks 

 

Marvin

 

 

[Redbeard]

I usually seal the wall with a lime parge coat. Although it is often not done this is quite important if using PIR (I wouldn't, usually), as the condensation risk assessments you get from the PIR manuf'rs will usually assume very good breathability *outwards* through the wall, on account of having closed the breathability path off completely with 2 sheets of foil. If the existing plaster is lime-based you may get away with leaving it, and augmenting where it never was (often behind skirtings, for example, and between Ground and 1st floors). Just make sure to strip off any non-breathable coatings.

 

I tended to use wood-fibre a lot more than PIR. Yes, it is expensive, but much better at 'managing' moisture from the room.

 

Even if you decide to use PIR I would strongly recommend using PIR *and plasterboard*, but not bonded. Yes, each sheet of insulated plasterboard has a VCL, and when you join them together, they don't! If you use separate PIR (or other insulation) and VCL you can tape the life out of the PIR before adding the plasterboard.

 

Yes, wood fibre is only about half the insulation value of PIR but is so much better in many ways. And it does not give off cyanide when it burns.

[nod]

Ideally you will need to tank the walls firs None of the Parge or lime will do this 

There are some very good slurry tanking on the market that won’t break the bank Then dot and dab insulated PB (pink) Followed with a gypsum mechanical fixing 

[Marvin]

Thanks for your thoughts @Redbeard and @nod

[Marvin]

10 hours ago, nod said:

Ideally you will need to tank the walls firs None of the Parge or lime will do this 

There are some very good slurry tanking on the market that won’t break the bank Then dot and dab insulated PB (pink) Followed with a gypsum mechanical fixing 

Hi @nod

 

I assume you would remove existing plaster first?

Edited May 3 by Marvin

[nod]

1 hour ago, Marvin said:

Hi @nod

 

I assume you would remove existing plaster first?

Yes 

it’s worth spraying a salt inhibitor on also Really cheap and quick