Temporary insulation of a flat roof

[jimAuk]

We have a flat roof of approx. 4 x 2.5m, for which we plan next year to convert to a pitched roof with rockwool insulation.

But until then, I have thought about covering the roof externally (like a warm deck system) with 75mm poly boarding, and then covered with normal flatroof stones to hold down the boards.

About £60 to do the roof.

http://www.diy.com/diy/jsp/bq/nav.j...efview=lister&ts=1294157748280&isSearch=false

As a temporary solution until next year, surely it will make the room a bit warmer?

 

[big-all]

assuming you pay 10p per kw that's 600 hours on a 1kw heater
or extra gas used say 1200hrs for your £60
so if the winter last 12 weeks that makes 50 kw on electric or 100kw on gas per week to = the cost
that's just additional heat over what you normally use