Should I add extra insulation whilst repairing flat roof?

southerly

I am recovering a flat roof and also had to replace about 1/3 of the chipboard sheets with OSB3. Is is worth buying some extra insulation and adding it in these areas, as I have not nailed the sheets down yet. There is already insulation there about 3" thick, but there would be room for a lot more as the joists are deep. Is there supposed to be any air gap left?

It is a very cold room as it faces north, and has 2 huge windows which would also lose lots of heat, and the walls are only one concrete block thick (no cavity).

I could even pull up the sound sheeting and add insulation to all the areas, even if this damaged the sheeting and I had to buy more OSB3, as from a builders merchant it is only £16 per 8x4 sheet.

phill99

Any increased insulation has got to be a good thing but make sure there Iis an air gap through.

southerly

How much air gap?

Wester

southerly wrote: »

How much air gap?

About 3 inches