Loft Insulation

[Bigfellah]

Can anyone tell me why power companies recommend 250 mm (10 inches) for depth of loft insulation when the beams are only about 5 or 6 inches? Also once insulated like this is it OK to place flooring in the loft and cover the insulation?

[scotman]

I wouldn't put flooring down if it is going to compress the insulation.

[The Builder]

There are other types of insulation that can do the job in less than 10 inches (oo-er), but they're far more expensive.
You just need to "plant" 5 or 6 inch joists on top of the existing, then floor that. As Scotters has said, don't compress the insulation.