Insulating Attic

[porkchop]

Which is best material to insulate attic at a reasonable price. Also are the 3/4 inch boards for attic floor nailed down or are they put down side by side.
Thanks

[BRIGHT SPARK]

Boards are best screwed down..as you may need to lift them to access wiring and will give less of a headache to the plaster below.If you want to insulate beneath the boards you will only have 100mm to 150mm at the most...so using rockwool or similar wont give best results. Celotex ..or equivalent will give better insulation values..but will cost more.

[The Builder]

If you lay 100mm or 150mm timber across the top of the joists first, you can then screw boards to that. It raises the deck way up above the ceiling.

You can then lay an increased thickness of loft insulation under the deck. Itchy fibreglass roll is probably still the cheapest.

Much easier to lay, though more expensive, would be bags of Vermiculite, or any other type of pellet insulation.

[SlackAlice]

This is what I did.

http://www.theanswerbank.co.uk/Home-and-Garden/DIY/Question1185837.html