Insulation under loft flooring

[NickyDee]

I live in a fairly new property 4 years old and wish to board out the loft for additional storage space.
I have established i can use loft boards from B & Q to do this, however having been up in the loft to measure up i have noticed that there is massess of insulation up there, it seems that it is between the joists and also running across the joists in a second layer.
can someone advise if i am ok just to squash down the insulation where i wish to board out and sit the boards over the top?

 

[PerryOne]

It is probably not a good idea to attempt to squash the existing insulation.
If the layer is between the joists then OK to squashing that.
If you take a look you will probably find that the insulation has been laid badly, and when you redo it, taking care to fill every hole, most of it will disappear. Insulation works by inhibiting the movement of air, leaving even a small hole can reduce the effectiveness of the insulation, when a strong wind blows over a home causing suction it strips the warmth from the home.
If the loft is high enough to walk round and carry things then 18 or 22mm (where you can walk )boards are required, dependent on joist spacing, if you can only crawl about then 9 or 12mm ply will do.