Loft flooring for storage only

[dylsi]

I plan to floor the loft of my house for storage only. Its a 1990s detached house with two steel I beams front and rear holding the roof (I presume). The joists to take the floor are 5"x2" at 16" centres (roughly).
I have three problems on which I need advice:
1) I am going to add insulation under the new floor. Which shoud I use? Currently there is loose spongy stuff there. I know to derate the cabling to current wiring regs, before anyone reminds me!
2) I need to move the access hatch and make it bigger but don't know where to get a door (Screwfix have two that are rather small).
3) What type of flooring should I use. There will not be much weight there but I don't want to put my foot through the floor when I go up.

Please help as my wife can't stop moaning that this project hasn't started yet!!!

Dylan.[/img]

 

[masona]

What type of flooring should I use. There will not be much weight there but I don't want to put my foot through the floor when I go up.

Can you get 18mm T&G P5 Grade (2400 x 600) through the loft because it will be cheaper then the loft flooring kits.
Put down 3"x1" flat across the joists in opposite direction to the centre width of the edge T&G board. This will clear any cable or pipe on top of joist and give you a cross air vent underneath.