Flooring Loft Over Insulation. Its been designed to protect the insulation underneath it whilst providing a safe deck for access and storage. You do not have to mess around with insulation or extra timbertoolstation sell something called loft flooring legsthey come in packs of 12 and cost around 17They fix to the top of the joist and raise the floor by 175mm and anyone can do itThey are only suitable for lofts though and are not structural so cannot be used if you intend on using the room as HABITABLE.
Loft insulation is a process of creating a barrier of insulating material within your loft. Screw the loft legs directly into your floor joists. You can still board directly on to the joists if you want but it is worth noting that this would not pass a building control inspection because you wouldnt have the full 270mm depth of insulation.
Insulated loft floor boards.
They should be fixed along every joist the floor will be. Even if you already have loft insulation. They are secured to the top of your joists within your loft via screws. Choose your tools and materials based on which type of loft floor insulation youre laying.