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How to Board Your Loft

The loft offers the ideal solution to anyone who is searching for extra storage space in their home, but how many of us use the space to its best advantage? Few people seem to realise that you can install a professional storage solution in the average loft for around £150 all in. Loft boards have a tongue-and-groove construction so they link together to form a solid, safe floor that you can walk on without watching your step.

Standard boards are commonly available in two sizes: 2,400mm x 600mm and 1,220mm x 320mm; and either 18mm or 22mm thick. The larger boards are available from your local timber merchant and are the cheapest and easiest way to create a loft floor. The main problem with these particular boards is actually getting them into the loft in the first place. Even when they have been cut down to suit the joists, these boards are often much too large to get through the average loft hatch. The smaller boards are sold in DIY stores. Prices vary a great deal for a pack of three boards, so it is certainly well worth visiting a few different outlets in order to get the best deal.

Loft boarding can be fiddly and you'll be working in a cramped and dusty environment; there will be frequent trips up and down the ladder, too. This is not designed to put you off the job, but these are the very things that will be running through the mind of a tradesman while he is adding to your quote. DIY has rarely made more sense!

Tool List

  • Tape measure
  • Pencil
  • Drill
  • Jigsaw and workbench (if you need to cut the boards to size)
  • Hammer
  • Hooded Disposable Overalls
  • Gloves
  • Dust mask
  • Screwdriver (ideally electric)

Step-by-step

1. 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. The 1,220mm x 320mm boards come in packs of three and cover 1.17 square metres per pack. The 2,400mm x 600mm boards are sold separately and cover 1.44 square metres each. Add a 20 per cent 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.

2. 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. Before you start laying boards, check the depth of your insulation. Government 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 here). 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).

3. 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.

4. 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 3).

5. 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.

6. Measure, cut and fit infill pieces as you go to complete the run of boards. Slide them into position with gloved hands, because 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.

Materials needed

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

Fitting a raised loft floor

A raised floor is the quickest and easiest solution for uneven joists. Installing a raised floor also means you can fit the required depth of insulation, whilst minimising the risk of condensation. Moreover, it is the best option if you have light fittings and wiring in the loft, and it also eliminates the time spent cutting loft boards to size.

You can use a product such as the LoftZone StoreFloor, which involves fitting plastic supports and metal beams to create a structure which you can screw normal loft boards on to. 

Not only is this very strong, but it also allows you to span over awkward joists, and it leaves an air gap above the insulation — thus preventing condensation. It's fitted in a few easy steps as shown below:

fitting a LoftZone StoreFloor raised floor

4 Comments

Is it allright to fit the loft bords and compress the insulation under it, my loft has two layers of insulation fitted. Will this be ok if I am not completly boarding the loft floor
Surely the joist sizes and span come into the equation, my joists are 3inch x 1.5inch at 16inch centres and span 12foot 6inch from wall to wall i wouldn't be happy boarding my loft knowing it could all collapse with the storage and timber floor weight on it.
Don't compress 2 layers take the top layer off put down boards and use your spare layer to fill the roof joists. Will need to hold it in with some twine and nails. Works well though.

You must use a sub frame first running opposite to your ceiling joists this adds height and strength use either 3x2or4x2 or 175mm stilts space nicely for your loft boards.
You then have room for you loft insulation to sit comfortably without squashing it and loosing efficiency.

See more by searching loft boarding nw on google.