Insulating underneath a staircase.

[MisterG81]

I have a 60's 3 bed semi.
Having just had the CH system overhauled, im conscious of various drafts - especially in the hallway.

The design of the house means the staircase goes up the side of an external wall, the area underneath the staircase - housing the gas meter is currently only accessible from the outside.. looking in the meter cuboard from the outide shows the bare wood of the staircase above..

What do people reccomend to insulate, or at very least reduce drafts from this area?

 

[PrenticeBoyofDerry]

Any standard insulation will do, it would depend on the method you use to box in, mineral wool is as good as anything and maybe finish of using MR plasterboard.