Levelling/skimming old brick wall before cladding

[andyscotland]

I'm converting my garage and have removed the old pebbledash from the (now internal) wall between house and garage.

The brickwork is ok, but a bit uneven - brick faces protruding/recessed by a few mm in places. It was obviously built like that as there was variation in the thickness of the render when I stripped the pebbledash. Presumably the brickies knew it was being covered and didn't worry too much about it.

I'm going to cover it with 25mm insulation boards (to reduce thermal bridging) and then plasterboard.

I think I should level the surface, to give a flat base for the boards and to avoid any little cavities that could give damp/condensation issues.

I don't think it matters too much if the skim cracks a little over time, it'll be held in place by the boards so it can't really go anywhere and it's not exposed to any weather.

As I also need to touch up the pointing of a few of the mortar joints I was thinking I could just skim all the low points with the same mortar mix to flush them up to the bricks either side.

Does that sound ok, or should I give it a proper coat of render/plaster? I need to keep the thickness as thin as possible for various reasons.

 

[Tigercubrider]

The insulation will be a lot softer than hacking away at bumps on the wall
Not sure if gaps are a particular issue?
Possibly something like expanding foam might stick and fill any gaps but most expanding foam has a life of it's own so you'd need to stop it pushing the insulation out.

 

[andyscotland]

Yeah, I definitely wouldn't be hacking away at the bumps, thinking instead I'd build up the dips with a bit of mortar/render. I agree expanding foam would be hard to do without it expanding everywhere and making things worse.

It's maybe not a huge issue, but I'd always understood it was good to avoid any gaps/voids between insulation and wall.

 

[Alastairreid]

If it is now an inside wall from a converted garage why bother insulating it?

 

[andyscotland]

The wall it sits against continues and is exposed above the garage roof, at front and back, and against the void below the main house suspended floors. So if left totally bare it'd leave a reasonable heat path around the new insulation layers. It's not getting full insulation, just a 25mm layer of PIR to minimise the bridging.