Chipboard flooring with tongue and groove joints is commonly available for flooring applications. They are relatively cheap and quick to lay. Standard size sheets are 2400mm x 600mm and available in two thicknesses – 18mm and 22mm. The tongue and groove edges make for a strong bond between the boards. Water resistant flooring grade chipboard should be used. Ordinary chipboard is easily damaged by moisture which causes it to swell and break up.
The chipboard flooring sheets should be stored flat in the room for a couple of days before laying them to allow them to acclimatise to differences in temperature and humidity. Whilst chipboard flooring can be nailed, it is notorious for working loose and squeaking so screwing them down is the preferred method of fixing and really doesn’t take long using a decent cordless driver.
Expansion gaps should be left around the perimeter of the flooring to allow for temperature and humidity changes. With suspended timber ground floors, expanding foam can be used around the edges to stop any draughts. The surface of chipboard is very smooth and this can make them slippery when handling. A useful tip is to wear decent work gloves which give better grip.
1. Mark the position of the joists along the bottom edge of the walls. This will make it easier to mark the boards and align the screws with the joists.
2. Boards are laid lengthways across the joists and ‘printed side’ up. Loose lay the first board so that its grooved side is towards the wall. Align it so that it is square with the joists and leave a 10mm gap along the wall edge to allow for expansion. In some situations, the boards against the wall will need to be cut in afterwards – see additional info below.
3. Use plastic shims or suitably sized timber wedges to maintain the expansion gap. This gap will be hidden when the skirting boards are fixed. Push the board tight against these shims whilst still maintaining alignment.
4. Use a steel straight edge to mark out the centre line of the joists. Align one end with the marks made earlier at the base of the wall, and the other with the centre of the exposed joist. Mark out the screw positions along these lines. These should be at 150mm centres along the joists and, the edge fixings should be no closer than 10mm to the board edge.
5. Using sharp pointed board screws will mean that you do not need to drill pilot holes first. Some of the best quality board screws are lubricated which allows them to drive quickly and easily through the chipboard.
6. Double check the alignment of the board before fixing. Starting at one end of the board, drive in the screws with a cordless driver. Set the torque so that the screws countersink themselves into the surface – but only just. Work your way along the board fixing across each joist as you go.
7. With the first board in place continue lengthways. Loose lay the next board butting the end of the previous one. Carefully align so that it continues to be square with the joists and insert shims along the wall edge to maintain the 10mm expansion gap.
8. It is preferable to have the end tongue and groove joint sitting over the centre of a joist. However, this is not always practical especially if the joist centres vary. Many people say that a ‘flying joint’ with tongue and groove boards is perfectly OK. If it is not practical to have end joints over joists, noggins can be screwed in position between the joists to give extra support.
9. Slide the loose laid board away from the previously fixed board and apply a bead of wood glue along the tongue of the first board. Push the board back into position so that the joint is good and tight. You can use a wooden chock and hammer to tighten if needs be. Wipe away any excess glue and mark and fix the board as before.
10. The final board of the first row will need to be cut to length. Measure from the end of the last board to the wall and deduct 10mm. Make sure the measurement is taken from the top edge not the edge of the tongue. Measure this gap on both sides of the board as the end wall may not be square.
11. Lay a new sheet of chipboard on a suitable bench or support and use the measurements to mark the face of the board on either edge. Use a straight edge and pencil to mark the cut line.
12. Use a hand saw to cut along the outer edge of this line. Keep the saw straight and square as you go and use long clean strokes. Cutting from the upper side of the board will leave a clean cut on this face.
13. Run a bead of glue along the tongue of the end of the previous board. Hold the newly cut board at an angle and line up the tongue and groove joint. Ease the board down to close the joint. Put packing shims along the edge to maintain the expansion joint. To tighten this board before fixing, tap wedges in at the end of the board. Screw down the board.
14. You can now start the second row. Assuming the off cut from the last board is greater than 500mm, you can use this piece. Square it off first if needs be. Check that the end will align with a joist. If not, either trim the cut end to suit or fit support noggins between the joists to align with the end.
15. The end joints should be staggered in a brick fashion. Using the off cut from the previous row will help with this and minimise waste.
16. Run a bead of wood glue along the corresponding section of the long edge tongue of the previous row and slide the board into position. Use a hammer and wood chock to tighten up the joint. Mark the fixings and screw the board to the joists.
17. Continue this process until you reach the last row to be fitted. Measure the gap between the top edge of the last row and the wall at 600mm centres. Deduct 10mm from these and mark them on the board to be cut. Measuring at 600mm centres will allow for any discrepancy in the line of the wall.
18. Join these marks with a pencil and cut along the outer edge of the line. Long cuts like these are a lot easier to do with a circular saw. To set this up, take a note of the distance between the edge of the saw base and the blade. Clamp a timber batten as a saw guide to the board to suit this offset.
19. The board should also be clamped firmly to the workbench so that it will not move as you cut. Check the underside of the cut line is clear and have an assistant support the off cut as you reach the end of the cut. Wearing ear defenders and safety goggles, cut along the board keeping the power cord well out of the way. Safety gear should also be worn by anyone else working with you.
20. Check that the cut board fits correctly. Run a bead of glue along the corresponding section of tongue on the previous row. Align the new board, holding it up at an angle. Gradually lower it into position and tighten the joint using the wedges or plastic shims.
21. You may have sections of board which need to be cut with a recess or step in the wall. To do this, carefully measure the profile required, and transfer this to the board. If angles are out of square, you can make a simple cardboard template first.
- Measure the width of the room and divide by 600mm to establish the width of the last row of boards. If this will be less than 150mm, you should shift your rows of boards so that you end up with a more substantial width for the last row. This will mean that you have a cut row along both sides of the room but each will be greater than 150mm. Both these cut rows should be fitted after the main section of flooring has been fixed.
- If the side walls are significantly out of square you will need to scribe in the first row and last row. In this case, you should also do this after the main area has been laid.
- To scribe in the boards, lay the board to be cut directly over the next row. Using a 590mm (600mm less 10mm expansion gap) batten with a pencil held against the end, run this along the wall carefully maintaining it at right angles. This will produce a pencil line along with the board accurately replicating the profile of the wall. Unless the line is straight, you will need to use a jigsaw to cut the board along this profile.
- Before starting to lay the chipboard flooring on old joists, clean up the top surfaces by removing old screws and nails. It’s important to make sure the boards can sit flat on the top of the joists
- As you lay boards, make a note of the position of any pipes and cable running under the floor. This will help to make sure you don’t accidentally fix into them and will also let future owners know their location.
- Choice of thickness for the boards will depend on the spacing of your floor joists. If they are spaced at 450mm or less, you can use 18mm boards. If the spacing is greater than 450mm, use 22mm thick boards.
- Provided you don’t anticipate having to lift the flooring again, glue the joints to make them even stronger. Some manufacturers even recommend applying glue to the top of the joists as well in an effort to reduce movement and squeaking often associated with chipboard floors.
- The screws used should ideally penetrate the joists by 1.5 x the thickness of the board. So, with 18mm chipboard, you want board screws at least 45mm long.
- Stagger the joints by a minimum of 500mm. The tongue and groove connection between boards means that the ends needn’t align with the joists, however, many people prefer to include noggins at this point to provide additional support.