How to Board a Loft: A Step-by-Step Guide

Loft boards
(Image credit: getty images)

By learning how to board a loft, you can not only drastically increase the storage potential of your loft, but also make it safer and more stable to move around in. This is especially useful if you are short of storage space in your home – the loft is often completely underused, so if you’re not planning on turning it into habitable space with a loft conversion, then adding loft boards and using it for effective storage can be a great solution.

Loft boards are fixed together relatively easily, but working withing the confines of the loft’s available space can make boarding a loft a tricky endeavour. Do heed the safety advice detailed below and only attempt the task if you are capable. If not, hire a professional.

If you want to board your loft, follow this step-by-step guide.

How to Board a Loft: Step-by-Step

You will need:

Materials needed:

  • Loft boards
  • 38mm, number 8 screws/ 4x40mm screws
  • Insulation material (optional)

Before you start:

  • Don overalls, gloves and a dust mask for protection, and finish off with a pair of trainers to aid agility in the loft
  • Set up a temporary work platform on a piece of board set across the ceiling joists — it is safer, and more comfortable, than trusting your balance
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Measure the area you plan to board out (multiply the width of the loft by its length). Take measurements in metres, this makes it easier when you are buying boards.

Standard boards are commonly available in two sizes: 2,400 x 600mm and 1,220 x 320mm; and either 18 or 22mm thick. The larger boards are available from your local timber merchant and are the cheapest and easiest way to board a loft. The smaller boards are sold in DIY stores.

The 1,220 x 320mm boards come in packs of three and cover 1.17m² per pack. The 2,400 x 600mm boards are sold separately and cover 1.44m² each. Always add a 20% contingency on top of your final square metre figure to allow for awkward cuts.

Before you buy the boards, check the edges for damage. The tongues-and-grooves are vulnerable to clumsy handling, so be very picky when choosing.

Before you start laying boards, check the depth of your insulation. Building Regulations guidelines recommend a minimum 270mm thickness of insulation blanket. But joists are usually no more than 100mm deep, so this would be impossible to achieve and still put a floor on top. Furthermore, squashing insulation down to fit joist height is a bad idea as this halves it’s effectiveness — doubling your heat loss.

The best solution is to build a raised loft floor above the insulation (details of which are shown below). 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 wouldn’t have the full 270mm depth of insulation required by regulations. Whatever you do, make sure you put as much insulation beneath the boards as possible.

(Do note that if you board directly on to the joists, you run the risk of causing interstitial condensation. This is where moisture condenses on the underside of the boards and drips down, causing damp. To avoid this you need to raise the boards up and permit a flow of air between the insulation and the boards. Only board directly on to the joists if you know there is no risk of condensation forming in your loft).

If you intend to board directly on to the joists instead of having a raise floor, then start by placing the first board across the joists.

If the board overhangs mark it at the centre of the last joist it crosses and make a straight cut at this point with a jigsaw. This allows the board that will butt up to its end to be supported by the joist.

For maximum strength the boards must be laid in a staggered pattern, in such a way that neighbouring joins do not line up. Lay a full board next to the first one and then mark or measure if it needs to be cut (see step three).

Cut the second board (if necessary) and slide it into position with the first board, making sure the tongue-and-groove is fully connected to form an almost invisible join. Fix with two or three screws along the join.

Measure, cut and fit infill pieces as you go to complete the run of boards. Slide them into position with gloved hands (the cut edges can be sharp).

Lay a block of wood along the outer edge of the board and tap it with a hammer if the tongue-and-groove connection creates too much resistance. This method prevents damage to the vulnerable board edges.

Things to note

Rather than having a run of uniform ceiling joists to attach to, older houses may have a mixture of old roof joists and joists put up to support a more modern ceiling. This can create a riot of different levels and cause problems with fixing boards. If this is the case, it may save time and make sense to go down the raised floor route instead.

Wiring in the loft often takes the most direct route from source to outlet. This means there could be wires strewn directly where you plan to lay a board. If there is enough slack in the wire, the joist can be notched and the wire run beneath the board. 

If you decide to do this, mark the position of the wire clearly on top of the board and make absolutely sure that you are not trapping the wire before you fix it down. A better alternative is to fix the wire with clips where it can be seen. 

If there is no slack at all in the cable then you may find that you have to disconnect the wire at its source before lengthening it using a junction box and some extra wire.

You are likely to come across the tops of light fittings while you are installing your loft boards. You can cut the panel to make access to the light easy and make a removable infill panel if the light falls mid-board. 

Be aware that recessed spotlights generate a lot of heat, so make sure that any additional insulation material you have fitted is pulled well away from these fittings to prevent a fire hazard. However, doing this will reduce the insulating properties and counteract any efforts to limit heat loss. 

It is now common practice to fit heat diffusers, or completely seal the area around the light fitting.