Porch insulation

[CalzorSuzay]

We have a porch which has a double glazed door and full height window to the front, single layer wall either side and single pane door and full height glass in sections entry to the house and a flat roof.

Redecorating it which currently consisted of wood chip wallpaper, 18 layers of paint, 2mm of foam and flaky plaster underneath it seems. The ceiling has stuck on polystyrene tiles so they're coming down as well.

What's the best way to board/line it up so I can then paint it, walls and ceiling?

I was looking at this http://www.wickes.co.uk/Celotex-25mm-High-Performance-Insulation-Board-1200x2400mm/p/190545 stuff for wall/ceiling but would I then need to plasterboard over it to be able to then paint it?

Is there a better solution? I'm obviously a newbie DIY'er

 

[freddiemercurystwin]

Unless it has heating then adding some insulation on the walls will do little to make it feel any warmer. And you may actually cause more condensation problems as you are making the whole thing more air tight. But if you really want to insulate it then yes you would need to add plasterboard.

 

[CalzorSuzay]

Yeah there's no heating in it, just trying to take the edge off it. I think part of the problem was the old letterbox letting the wind in and the top of the walls look to be drafty in the corner, probably once I seal this up it'll probably help anyway.

I know when I take the wood chip wall paper and 2mm of polystyrene down half the plaster is going to fall off so what's the best way just plasterboard it?