General fitting guidelines
The work area must be completely clear of obstructions.
The floor must be scraped and swept clean. Check the floor for flatness before commencing to establish any high spots. In the cases of badly uneven floors. Latex self leveling screed may be needed to level the floor. If this is not followed you may find that the floor bounces and does not sit flat. Providing this is not too bad it may eventually settle.
Preparation Work
 Expansion; Timber expands and contract due to changes in humidity.
For this reason it is necessary to allow expansion gaps to the perimeter of timber floors and some times within the floor itself. To be on the safe side10mm expansion per 1m run across the boards is required.
This means that a 3m wide room will have 30mm of expansion allowance.
Although timber expands and contracts far greater across the grain than it does along the grain there should still be expansion to the ends of the floor. Expansion gaps should be left clear. Do not fill them with cork.
In theory, (given the average domestic width of room at 3.5m wide) if you could physically sit in the centre of the finished floor and move it, you should be able to move the floor in any direction by 15mm. This means that any obstructions such as radiator pipes which pass through the floor should have expansion around them.
Although Engineered Wood Flooring is so much more stable than natural flooring we still recommend that you follow the fitting guidelines herein.
Expansion can be built into the width of the floor by laying with washer gaps between the boards if the need arises. (Fig 4).
In the case of Engineered Wood Flooring this is for appearances rather than necessity.
It is sometimes required to remove skirting and cut back plaster or dry lining to allow extra expansion. (Fig 5)
It is important to check around the radiator pipes periodically to make sure the floor does not expand onto them.
It may be required to ease the floor in front of them to allow further expansion in time. (Fig 6)
Insulate any hot water pipes that run under the floor.
Mark doors for cutting to length before removing them.
 Place an off cut of the flooring to the base of the door and hold a pencil flat to the face. (Fig 7)
Mark the door all the way across. Repeat this with the door in different opening positions.
This should give you a clearance cut line about 4 - 5mm above the new finished floor level.
Now remove doors and set aside ready for cutting.Undercut door linings to allow free movement for expansion.
Expansion must be allowed under door linings. (Fig 8)
Place an off cut of flooring at the base of the lining flat to the floor.
Holding a sharp saw flat to the face off the off cut cut the lining and architrave and also 45mm of the abutting skirting if it is existing. Professionals might use a fein cutter or electric tenon saw to make this task quicker and easier.
Remove the timber beneath the saw cut with a very sharp chisel.
Sometimes it is necessary to nibble away the corner of the studwork or masonry behind the lining to achieve a full 15mm expansion gap.
Sub-floor condition
The work area must be completely clear of obstructions.
The floor must be scraped and swept clean. Check the floor for flatness before commencing to establish any high spots. In the cases of badly uneven floors latex self leveling screed may be needed to level the floor.
Underlay and D.P.M
If you’re laying an engineered wooden floor then an underlay must be installed between the wood floor and sub-floor and must also wrap up the wall to protect the edge of the floor. This acts as an insulator and buffer.
This must be sealed at all joints with a moisture resistant tape.
On any ground floor a damp proof membrane (DPM) must be used with 200mm overlaps sealed with tape also and turned up the wall.
It is best to lay the insulation first and then the D.P.M. This way any possible condensation will be decreased.
Fixed Floors
You can also fix direct to joists (Fig 39). However a minimum of 6mm ply (another option is to use 18mm chipboard as this may be cheaper, but remember the thickness buildup) as an intermediate layer is required to support the butt joints of the boards which may land between joists. The ply is required to be fixed to the joists.
By putting down ply or chipboard it will enable the other trades (plasters, decorators etc) to complete there work quicker and safely prior to the hardwood floor being installed.
The absence of the need to cut the lengths of flooring back to the joist supports means a greatly reduced waste factor in the use of the floor.
Chipboard etc is cheaper than hardwood flooring!
It is possible to fix your ply sheets direct to the screed. This is not necessary but some builders feel happier doing it this way. It will not have a detrimental effect on the floor.
Floors can also be screwed and plugged direct to the screed. The advantage f this is that it saves the height (20mm wood and 20mm of ply). But it is very time consuming.
Not for the faint hearted. |
