Guide to Installing Insulated Loft Decking

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Providing a storage area in your loft, improving your insulation and cutting your fuel bills


Make sure you know how big a storage area you want.  Each of our Insulated Loft Decking board measures 1 foot x 4 foot  (0.3m x 1.2m) and covers an area of 4 square feet ( 0.36m2). They are delivered in packs of two, so each pack will provide you with a storage area of  2 foot x 4 foot (0.6m x 1.2m).

Our recommendation is that you will need at least four boards, which will provide you with a handy storage platform of 4 foot x 4 foot. Of course, it is easy to increase this with additional Insulated Loft Decking boards.

The installation of Insulated Loft Decking will add additional weight to the roof structure – each board weighs just under 5 kg.  And of course the items you will store in your loft will increase the load on the ceiling joists, so it is advisable to make sure that the increased load can be supported by the existing roof structure.

What you will need

Make sure that the loft is well lit, so that you can see what you are doing. It is sensible to wear a simple dust mask since old lofts are normally dusty places; wearing protective gloves is also recommended.

If you need to cut the Insulated Loft Decking boards, you will need a standard fine-tooth saw. In this case, in addition to gloves and dust mask, safety goggles are recommended.


The boards should be fixed to the joists using wood screws, so you will need an appropriate drill, together with 150mm long wood screws and, of course, a screwdriver.



In the loft, make sure that the designated area where you will be laying the Insulated Loft Decking is clear from any obstructions and trip-hazards.

It is sensible to make sure you have enough space around the designated area to allow you to use temporary support boards which you may need to stand on whilst installing the Insulated Loft Decking boards.

To get the maximum thermal insulation performance, Insulated Loft Decking works best when it is installed in contact with normal insulation (fibreglass rolls) fitted in between the joists.  Make sure that there is some fibreglass insulation in the area where you will be fitting the Insulated Loft Decking.

8298If there is no existing loft insulation, you will need to lay some before you proceed. It should be of a thickness just level with the top of the joists – usually 4 inches (100mm). SuperLoft Blanket, fully encapsulated and itch-free, is ideal for this purpose.

It is essential that the top of the loft insulation is just in contact with the bottom of the Insulated Loft Decking boards – any continuous air gaps would mean the insulation is not as effective as it should be.

General precautions when fitting loft insulation

  • Insulation should not cover light fittings – there should be at least a 3 inch (75mm) space between loft insulation and light fittings
  • Electrical cables should never be left underneath loft insulation in case they overheat. They should be re-positioned above the insulation
  • PVC-sheathed cables should never come into contact with the insulation component of Insulated Loft Decking boards
  • Insulation should never be fitted beneath water tanks.


Fitting instructions for insulated loft decking


    1. Insulated Loft Decking boards should be offered through the loft hatch one at a time – the size and dimensions of the boards are designed to make lifting and handling an easy task. Once in the loft, the boards should be laid at right angles to the ceiling joists, and with the chipboard surface uppermost.
    2. Each board should be supported by at least three wooden joists. Where it is not possible to fully support the edge of a board on a joist, the use of timber fillets attached to the sides of the joist, or other safe and effective method of support, should be considered. It is essential that the edges of boards and any overhangs are fully supported.


  • Once the first board is loose-laid in the correct position, it should be fixed to each joist below with a wood screw. A subsequent board should be laid, and butt-jointed to the first board, long edge to long edge. This second board can now be screw fixed.
  • This process can be repeated with subsequent boards.
  • When drilling and screwing through the boards, ensure that there are no pipes or cables in the vicinity, and that you are fully aware of the location and position of nearby pipes and cables.