Internal wall insulation

Green_hopeful

My son has a flat in a 1960s block which has a large cupboard which backs onto the stairwell in the block. The stairwell is internal but the windows are louvre so do not stop any airflow. The external walls have cavity wall insulation so the cupboard back is the coldest surface in the flat.

He has noticed some condensation on the back wall so we are looking to insulate it. There is some polystyrene wallpaper in the cupboard so I guess at some stage there might have been an attempt to resolve it previously. He already runs a dehumidifier so I suggested he run that a bit more in the meantime. It has shelves and a hanging space. Roughly measured it is about 2.4 m high and 2.8 m wide so quite big. 

My inclination is to remove the internal shelves etc and glue some 50mm celotex board into the back. It would be good to get some extra insulation to keep them a bit warmer anyway. You don’t see the back so I might then wallpaper the celotex board with some vinyl wallpaper rather than using plaster fronted board. 

What do people think? We will do it ourselves but haven’t done anything similar before. 

grumbler

IMO, any 'insulating wallpaper' is useless. 50mm of Celotex is good, possibly even 25 in this case, but it's better to use insulated plasterboard

 

  Normally you screw it to batons fixed to a wall, but it's possible to screw it directly to the wall.

Leon_W

I've just internally insulated an extention to our kitchen.

Used Knauff boards of this from Wickes  https://www.wickes.co.uk/Knauf-XPS-Laminate-Plus-Insulated-Plasterboard-Tapered-Edge---27mm-x-1-2m-x-2-4m/p/163699

And a few tins of expanding foam ADHESIVE from Screwfix  https://www.screwfix.com/p/no-nonsense-expanding-sticky-foam-gun-grade-750ml/6576h

Just finishing the taping and i'm going to get our friendly plasterer to give them a skim.

I regularly sit in a sofa in this area and previously you could feel a really cold draught rolling down the cold walls. Much better now and should have done it years ago really.

Green_hopeful

Thanks all. Sounds like it will work. 

Expanding foam always reminds me of the cook porridge cook fairytale. I was using it to fill a gap in the ceiling. I underestimated how much it would expand and got covered in very sticky expanding foam.