Sign in / Register

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; both are 18mm 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. If you have a large loft to board then it may be worth extending the loft hatch to take the bigger boards it will save you a lot of work in the long run. 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.

To get the best possible insulation you can, use a special loft board such as Knauf's Supadeck. This is 123mm thick by 1,200mm long and 600mm wide. When used in conjunction with a 100mm layer of standard insulation underneath, Supadeck gives the equivalent of 270mm of insulation (SEE STEP 2).

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 another nought to your quote. DIY has rarely made more sense!

Tool List

  • Tape measure
  • Pencil
  • Drill
  • Jigsaw
  • Hammer
  • Hooded Disposable Overalls
  • Gloves
  • Dust mask
  • Screwdrivers
  • Workbench


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 270mm thickness of insulation blanket. Even with the deepest joists this would be impossible to achieve and still put a floor on top. Knauf's insulated Supadeck is one solution, another is boarding out only part of the loft and fully insulating the rest. You could also consider putting as much insulation beneath standard boards as possible and then fix a foil-type insulator to the inside of the roof trusses later on.

3. Place the first board across the joists. If the board overhangs (as in the picture) 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. Drill two or three pilot holes along the join and then fix with screws.

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 tongueand- groove connection creates too much resistance. This method prevents damage to the vulnerable board edges.

7. 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. In this loft we were faced with a 3m x 2m section of modern ceiling joists hemmed in at both ends by original oak joists. The oak joists sat 30mm higher than the ceiling joists, but by using a spirit level to line up and fix additional pieces of timber to the oak at both ends, we were able to floor the whole area without any drama.

8.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, as with this aerial co-ax cable. 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.

9. You are likely to come across the tops of light fittings while you are installing your loft boards. 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.

10. If your garage has a pitched roof, you can probably make use of the storage space above your head by adding some loft boards. Garage roof trusses will have some form of strengthening section that connects the pitched part of the truss with the horizontal joists. In this case it is a vertical piece of timber, but designs do tend to differ. The boards will have to be cut round this section if the tongues-andgrooves are to meet up. Start by laying a board either side of the section. Now measure the depth of the section.

11. Mark off half the depth of the section on each of the boards. Next, mark the width of the section on the boards, being sure to allow a couple of millimetres extra on either side.

12. Cut out around the marks you made in step 11 and slide the boards into place. They should meet in the middle of the section with an even join along their length.

Materials needed

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


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.