How to Fit Loft Boarding over Insulation

How to create a safe storage space in your loft without compromising the insulation.


For anyone with a loft, it seems an obvious decision to use the empty space upstairs to store all of the empty boxes and other homewarwe which isn’t needed most of the time, but fitting loft boarding over insulation can pose a problem.

Lofts should always be insulated to at least the recommended level of 270 mm, and up to 300mm is preferable where possible. However, studies have shown that the effectiveness of insulation in a loft can be badly affected by the loft space being used for storage purposes. When you fit loft boarding over insulation for storage purposes, the insulation is ordinarily compacted to the height of the joists between which it is fitted. This is usually a rather low height of either 75mm or 100mm. Otherwise, insulation is often compressed by items placed directly on top of it. This reduces the thermal performance of the insulation and undermines the effectiveness of the material.

Fitting Loft Boarding over Insulation: the Solution

The only solution to the problems associated with fitting loft boarding over insulation is to place above the joists a free-standing platform which does not compress the insulation. You will be able to achieve this in one of a variety of ways:

- When working with a truss roof it is possible to fit bearers on the timber work

- The platform can be hung from the purlins

- Erecting a vertical set of stilts protruding from the ceiling joists will provide a base to place the loft boarding over insulation

Of course, when fitting loft boarding over insulation the main consideration should be the stability of the structure. This is especially important if you intend to store large or very heavy items in the loft. It could be extremely dangerous to have items falling through the ceiling into the rooms below.

If you are in doubt over structural stability then seek out the professional advice of a structural engineer.

Lastly, make sure to take into account the loft hatch, which should be well insulated and draught-proofed.

Image: Christine und Hagen Graf

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