The advantage of this type of insulation is that no cutting is required, making it easy to lay in a loft where joists are irregular spaced.
Laying the loose insulation: It is supplied as granules which are poured from a sack and spread across the floor area between the joists. To gain the required depth of cover, unless you have particularly deep joists, will result in the joists being covered. You will therefore need to build up the level of joists in some areas to support some form of boarding to provide a means of access to the various areas of maintenance - i.e. water tanks. Without such access, you won't be able to see where it is safe to stand, as the joists won't be visible.
As with the blanket material, you will need to keep the insulation clear of eaves ventilation, cables, light fittings and beneath the water tanks. To do this, use lengths of wood or hardboard to hold it in place.
If you have water pipes running along the floor, you can lay a lengths of wood or hardboard along the sides to prevent the granules flowing underneath. This way, the heat rising through the ceiling will keep the pipes warm and prevent freezing.
Pour the granules from the pack, starting at one end of the loft, and use a batten or broom to sprad them to the required depth.
Nail battens around the edge of the loft access panel to form a recess for the material. Once this has been filled, cover with a piece of old sheet and fasten with drawing pins or staples. If you don't, the granules will tip out easily. You may also fit a draft excluder to prevent heat loss around the door opening.