Want to board loft, any advice?

[Dubhghaill]

I've recently run out of space with mine and my girlfriend's hoards taking over the place, so I want to board up the loft for storage. Once it's done, I'd like to be able to use the loft for a trainset as well.

It doesn't have to be entirely habitable; nobody will be living up there. But I do want my belongings to stay clean, dry and at a reasonable temperature.

Currently the loft is very dusty and dirty, and there's nothing behind the tiles, so all the dirt from outdoors makes its way inside with the wind. Also, we recently had insulation fitted. This seems to be in two layers: one is up to the beam height, and then another layer across the top.

I tried taking some pics but they didn't come out too well (click to enlarge):



There was a Sky engineer here and he didn't bother putting any of the insulation back, as you can see from the pics.

My plan is to use thin plasterboard behind the tiles to stop the draught, and then plywood across the beams.

Anything I should know or do differently?

 

[PrenticeBoyofDerry]

For you floorboard/pnels, you will need to install new joist at 170mm deep at right angles to your existing joists.
This will give a good, sound fixing point and allow you your extra insulation layers as you raise the floor above or level to the insulation, so you can board it out, the new joist should be spaced at 400mm centres.
It will also be a good idea to insulate the slooping roof, so best insulation to use is blankets or celoxtex/kingspan like sheets, leave 50mm ventilation between insulation and roof tiles, this can then be boarded over, a vapour check barrier would be advised as extra prevention against condensation.
You could also consider using thermaline boards.
But before you do this are you aware of the type of electrical circuit that are routed through your insulation?
You need to be careful, that the current carrying capacity of these has not been effected by the insulation.
Lighting circuit on 6A MCBs are normally okay but any other power circuits like sockets, showers, ovens etc.. will need to be calculated as the cable will be derated due to the covering of thermal insulation.