A Floating Floor

A floating floor is a floor that is laid over a existing timber or solid floor without being mechanically fix down, eg nailed or screwed.The floor is fixed together in such a way that it becomes one big sheet and is held down by its own weight.

When using solid Hardwood flooring it is advisable for the boards not to exceed 100mm in width as wider boards are more likely to cup. If wider boards are preferred a fix method of installation is needed. This is obviously not necessary when using Cathedral Flooring.

An expansion gap must be maintained around the perimeter including under door linings etc to allow for expansion. An expansion gap must also be allowed around any radiator pipes etc which pass through the floor.

If the floor is restricted from expanding it will raise and become springy.

This expansion gap is covered when the skirtings or beads are fixed.

Boards can be fixed together by gluing the top of the tounge and the bottom of the groove (Fig 9) or by screwing or nailing to a batten which itself is not fixed down (Fig 10).

Floating Floor (Raft System)

  

If the concrete slab is flat and level, polystyrene can be used as a substitute for the screed to make up the levels (Fig 11). This can save drying time and also provide extra insulation.

Floating Floor

Lay the floor by gluing together all four edges. Apply the glue to the top of the tounge and the bottom of the groove. (Refer to setting out)

Some times you may have difficulty pushing the boards together due to a vacuum being caused in the groove by the glue trapping in air. To stop this from happening apply 200mm lines of glue with 25mm gapes between them.

This will allow air to escape and then the glue will spread along the gaps.

If the glue squeezes out on top of the floor you may be using to much glue, but be sure to use enough.

Lay 3 runs and leave for 30 minutes for the glue to set before continuing.

This forms a solid panel which stops the floor from coming apart when you really get going.

Strap clamps are very useful for pulling the boards tightly together.

Check that the butt joints are tight. A pull bar is useful for tapping up the last board. (Fig 12)

If possible work with the tongues pointing towards you.

When tapping up the boards use an off-cut of flooring between the hammer and the tongue to stop the tongues from being damaged. If the tongues become damaged it will be necessary to remove the damaged part with a sharp chisel.

If you hammer against the groove side of the board and cause damage you will have to discard that board.

Make sure you stagger the header joints of the boards for the best appearance. Try not to get too many header joints in line as you look across the floor. The closest the header joints should be is twice the width of the boards.

For ease of sanding make sure the header joints are at least 200mm away from the walls on the ends of the boards.

Method of cutting scribes / infills to walls

A and B are the last two full width

boards laid (Fig 13)

Place a spare board c on top of b so that it lines up perfectly in width.

Using a piece of flooring cut to length 15mm longer than the width of the boards and held against the wall mark board c to be cut. e is the face width of the piece of flooring that when laid in the remaining gap will leave a 15mm parallel expansion gap.

The scribing block d is always cut - the width of the flooring + the expansion gap required.

Stair scribe

Don't forget to allow expansion to the bottom of stairs by under cutting the bottom step. (Fig 14)

The load on the bottom step will rest on and be transposed through the hardwood floor to the subfloor or packing shims.

Joints between doors

The floor must be separated by an expansion gap between rooms to allow each area to move freely. (F ig 15)

If this is not done the compounding expansion may cause problems.

The expansion can be covered by a surface threshold fixed to one floor only and held down by the door stops.

Door opening between two wood floors with dividing expansion joint from stone to wood or wood to wood.

Intersection of wood flooring to stone

This can be achieved by keeping the wood surface 7mm higher than the stone and rebating it to allow the wood to expand and contract. Door opening onto wood floor away from stone or tile. (Fig 16)

Wide floors and expansion - secret fixed floors.

Sometimes there is the need to allow for expansion within the width of the floor because the perimeter expansion allowance will not be enough. (Fig 17)

This can be achieved by using washers to space the boards as they are laid.

It is advisable to leave the washers in for a few rows and bring the back row forward as you add moor boards.

This stops the gaps closing up as you tap up the new rows.

Expansion around hearths (Fig 18)

Methods of jointing end boards, thresholds etc to the floor.

Usually required in doorways. (Fig 19)