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Laying your 19mm Tongue and Groove floor

You can lay your new floor on a concrete base, on an existing timber floor or directly on bearers and joists. Each has its own method of attachment. This brochure tells you what to do and how to do it. To make accurate end-to-end jointing easier, Boral Timber mills 19mm tongue and groove floorboards either with plain-ends or "endmatched" - with a tongue continuing around the end of each length. Endmatching saves wastage as you can now lay a strong floor without cutting each board to end on a joist.

Local Environment
Being a hygroscopic material, timber will be affected by conditions of excessive moisture or drying. In your home conditions such as heaters, air-conditioning, exposure to sun from large windows and moisture sources mean you must allow the boards time to adapt to their new location. Otherwise, you risk future problems of shrinking (drying) or expansion (moisture) as well as possible damage to the underfloor structure.


Acclimatisation
Wherever you intend to lay your floor, acclimatising the boards will prevent most environmental problems. The conditions in the room or areas where the timber is to be installed should be equal to those that will prevail during the life of the floor. The acclimatisation period should not include any excessive weather conditions either rain, or heat. If you do get such excessive conditions start your acclimatisation when the weather returns to less extreme conditions. You can lay and acclimatise the boards in place or stack the boards in an open or criss-cross fashion so that air is free to circulate in and around each board. The minimum time you should allow for acclimatisation is 14 days for good underfloor ventilation and 21 days minimum if underfloor ventilation is poor. The floor should not be installed until the equilibrium moisture content (EMC) of the timber is equal to the EMC of the room and has stabilised. The only way to verify this is to use a moisture meter (available for hire from Boral Timber) to verify that the EMC has stabilised. Where conditions apply such as air conditioning, underfloor heating, large glass areas in windows or doors, or in high humidity locations (such as poor drainage or ventilation), we recommend you call us for technical assistance on 1800 818 317.


Laying the floor
Sort the timber into two stacks; one of similar-length boards and one of varying lengths and start by laying the varying lengths, longest first, in a triangle or "rack" from one corner Lay the first board with its groove towards the wall and leave a 12mm expansion gap all round the room between the floor and the wall (not the skirting, if any). This gap will be covered by the skirting. You can retain existing skirting if the new board slides comfortably under it. If not, you will have to remove the skirting. Continue each row by laying the similar-length boards in each row, adding and cutting short lengths to finish the row (still leaving a 12mm gap). There must be at least 450mm distance between butt joints in adjacent rows (see illustration below).




Distribute end-joints evenly
Plain end boards must be joined on a joist (not necessary with endmatched boards). Make sure all joints (endmatched or plain) are distributed evenly and do not cluster in any one section of the floor. Push endmatched boards together before using your tapping block to prevent damage to the tongues. You can make a tapping block from an offcut of board.

If the wood is not acclimatised, do not cramp or nail the boards together at this stage.

If you want to walk on the floor during acclimatisation, tack the boards in a few places to hold them on the joists. To protect the face of the boards from damage during acclimatisation we recommend that you lay the boards upside down. Allow the loose-laid floor to acclimatise for 14 to 21 days, depending on the quality of ventilation. When acclimatisation is complete remove the tacks, turn the boards face up, and start to lay the floor, tapping the boards together again if necessary.


Nailing the boards
When the boards have acclimatised correctly, secret-nail them permanently to the joists or battens with a secret-nailing gun, or cramp them and top-nail with a traditional hammer or standard nail-gun. A secret-nailing gun will "kick" the boards together at the same time as it drives the nail in at 45 degrees. If you intend to secret-nail by hand be sure to use a nail-punch to avoid damage. On an old floor or on a ply or particleboard base use an elastomeric glue as well.
If you are top-nailing the floor directly on to joists, attach floor-cramps to a few joists to lever the strips together evenly across the room. You should be able to hire floor-cramps from a good tool-hire firm. Cramp about nine or ten boards at one time - do not cramp two or three strips together as this may set up excessive strains in the floor (over cramping).

To avoid splitting boards you should pre-drill nail holes at the end of plain end boards when top-nailing.

Nails to use

Secret-nailing
For a secret-nailing gun use 45mm-long T-head nails 2.2 to 2.5mm in diameter If gluing and nailing to 12mm ply use a shorter 38mm nail.

Top-nailing
For a top-nailing gun use 2.2 to 2.5mm finish-heads, 45mm long (2.5 times the timber thickness), 2 per joist.


Hand-nailing
Use 2.8mm diameter finish-head nails, two nails per joist for top nailing and one nail per joist for secret nail. Scribe and cut the last board to the profile of the wall and tighten up by hand, or lever with a chisel.