Insulation boards, whats the best way to do it?

[banjodeano]

Hiya guys, i am thinking of putting some insulation boards on the inside of an external wall, but i have a couple of questions that are puzzling me, firstly i read that the boards are fixed to batons fastened to the wall, leaving a gap behind them, the gap increases the thermal effect, is that the best way to do it and what size gap would you leave? and also, i am thinking about having some bedroom units fixed to this wall, would it cause a problem for someone to fit units onto insulation boards, and also would these boards need to be plastered over, at the end of the day they will not be visible.
thanks for any input

 

[Notch7]

My understanding is that the insulation is pushed flat to the wall, no gaps anywhere. Use standard foil faced celetex of equivalent. Foil tape all joints so there are no gaps to create vapour barrier.

Fix 50 x 25mm battens flat on the insulation.

Then fix plasterboard -probably foil backed as the primary vapour barrier.

You will still have a cavity, but on the warm side Also your timber battens are on the warm side so less likely to get condensation on them.

 

[banjodeano]

Thanks notch7, great advice,