A guide to the installation of Junckers 20.5mm, 22mm and 14mm clip system floors
22mm and 20.5mm - sports, commercial and domestic 14mm - domestic, light-duty commercial
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Please follow these simple instructions
STAGE 1 - BEFORE, DURING AND AFTER INSTALLATION
In the area where the floor is to be stored and laid, conditions Wood is a hygroscopic
material. Changes in humidity will cause natural must be the same as expected when
the area will be in use. The expansion and contraction of the floor. Small gaps
may occur. room must be weathertight, heating system in operation and wet trades
(eg. plaster and cement) must be fully dry. Any damp problems must be remedied first.
The relative humidity of the air should remain between 35% 65% RH. Heating and/or
ventilation may be necessary to maintain Also see information sheets, Ref: C2.1.1,
C5.1.1 and C3.1.1 conditions. This is especially important in newly built or renovated
properties, or those which may remain unoccupied for some time after the floor is
laid.
The floor should be delivered as near as possible to the time when it is to be laid.
The polythene wrapping is left intact during storage and the flooring must not be
allowed to "acclimatise". The polythene wrapping is not waterproof and must not
be considered to be protection against damp. Packs can be opened for inspection
upon delivery, but should be resealed until the time of fixing.
STAGE 2 - SUB-FLOORS - General notes and preparation
Junckers Clip System Floors can be laid upon most types of dry, level sub-floor,
including sand and cement screed, and timber such as floor boards, chipboard etc.
1. Sand and cement screed
No more than 3mm gap under a 3m straight edge
Maximum 5% moisture content
Maximum 75% Relative Humidity
Note: For floors with higher levels of moisture, contact Junckers
Technical Department.
These must be flat and fully dry. This means the moisture content must be maximum
5% or 75% Relative Humidity. On ground and all cementitious floors, a surface moisture
barrier of Junckers SylvaThene polythene, Sisalkraft Moistop 728 or PolyLay must
be laid with the joints well lapped and taped, and turned up at the walls. The screed
must be levelled to a tolerance of no more than a 3mm gap showing under a 3m straight
edge. A self-levelling compound may help to achieve this tolerance if the base is
found to be uneven.
2. Timber sub floors
These may be floor boards, chipboard, ply or similar. Ensure the floor has adequate
protection against damp from below. If the floor is on joists, ensure the void below
is ventilated to building regulation standards. Air-bricks must not be blocked.
The moisture content of the timber base must be 12%–14%. It must be soundly fixed
and flat. The base must be levelled to no more than a 3mm gap showing beneath a
3m straight edge. If the base is unlevel, it is sometimes possible to achieve a
flat surface by sanding or securely nailing down plywood of sufficient thickness.
3. Mixed sub floors
Junckers Clip System floors can be laid onto a base made from more than one material
eg. part screed, part timber.
Clip System Floors may be laid onto polystyrene insulation, with a moisture membrane
underneath. No additional underlay should be necessary.
Polystyrene must be tongue and groove jointed and have a minimum density of 20kg/m3
for 22mm and 20.5mm floors, and 40kg/m3 for 14mm floors.
STAGE 3 - CHOOSING UNDERLAYS
The range of underlays is as follows:
For 22mm, 20.5mm and 14mm floors
PolyLay
An underlay and moisture barrier. 1.5mm thick for use in domestic and commercial
installations. Offers good step sound absorption and cushioning.
2mm SylvaFoam and 2mm SylvaFelt
For commercial or domestic floors laid onto timber sub-floors and where a moderate
amount of shock absorption is required. Additional moisture barrier is necessary
if laid onto cementitious floors.
For 22mm and 20.5mm floors
5mm MultiFoam
Sports or multi-use applications where good shock absorption is needed. Moisture
barrier is necessary when used over cementitious floors.
10mm ProFoam
Sports floors where a floor fully complying with standards BS7044 Part 4 and DIN
18032 Part 2 is required. Moisture barrier is necessary when used over cementitious
floors. Note: With underfloor heating systems, a second layer of Junckers Sylvathene
is also required. See separate Guide E4.1.
SELECTING THE CORRECT SIZE OF CLIP
Three Clip sizes are available, each to suit the humidity level expected when the
building will be in use. Select the Clip size using the table below (see back page
for further details).
Site Conditions Relative Label Clip Clip Humidity Colour Type Size Dry, well heated
One 35%-50% Green 129.1mm constant conditions Hole Mostly well heated, Two 45%-65%
Yellow 129.4mm some fluctuations Holes Intermittently/rarely Three 60%-90% Mauve
129.8mm heated Holes
CLIP CONSUMPTION
Domestic installations: 13 clips per m2
Commercial and Sports installations: 17 clips per m2
Wide Board Range Floors (20.5mm): 17 clips per m2
STAGE 4 - EXPANSION ALLOWANCES
Gaps will be necessary around the floor’s perimeter and ALL fixed points.
Gaps at “A” must be left empty. For 22mm and 20.5mm floors, these gaps must be 2mm
for every metre of floor width at each side, minimum gap 15mm. For 14mm floors,
3mm for every metre of floor width at each side, minimum gap 15mm.
Gaps at board ends, B, are to be filled with Junckers Cork or Rubber Strip, ensure
the strips are a close fit in the gaps. The size of these gaps to be 1mm for every
metre of floor length, minimum 10mm at each end. The gaps and strips are usually
covered with a skirting, quadrant or scotia moulding, available from Junckers.
STAGE 5 - INSTALLING THE FLOOR
When installing a surface moisture barrier, ensure the sub-floor is free from loose
particles.
Unroll the moisture barrier and extend it up the walls just over the finished height
of the skirting. (To be trimmed off after the skirtings are fixed). (Fig. 3). Ensure
the moisture content of the cementitious base is less than 5%. It is not possible
to cover up a damp problem with a moisture barrier. It will protect the Junckers
floor from residual moisture only. For SylvaThene and Sisalkraft, edges must be
lapped by 100mm and taped with Junckers Waterpoof Tape. Sisalkraft is placed black
side downwards. The underlay is then placed over this. There is no need to fix the
underlay or moisture barrier to the base.
PolyLay is laid felt side downwards with the polythene edges lapped. No additional
moisture barrier should be necessary.
LAYING THE FIRST ROW OF BOARDS
Use temporary spacer blocks to form the correct size expansion gap between the wall
and the first board. Note: these must be removed upon completion. If the wall is
not straight, it may be necessary to scribe the first row of boards to suit. Check
the expansion gap can easily be covered.
With a hammer, tap the correct end of the Clip into the groove on the back of the
board. This is the end with the holes. The plain end of the Clip must point towards
the board’s tongue, as shown below.
Note: take care to align the Clip correctly before hammering. One firm tap with
the hammer is usually necessary. Excessive or repeated hammer blows may cause the
Clips to become loose. Note: The Clips and boards must NEVER be fixed directly to
the sub-floor! Lay the board in place, tongue pointing away from the wall. Continue
to the end of the row, cutting the last board to length. The offcut will be used
later. All board header (end) joints must be glued with Junckers SylvaFix Adhesive.
Excess adhesive must be wiped from the surface with a damp cloth (see below). Never
apply glue to the long joints (except last board - see below).
SECOND AND SUBSEQUENT ROWS
The off-cut from one row of boards is then used to begin the next row. Ensure the
board and stave (strip) end joints are staggered to produce a random strip pattern.
They must not fall into line on adjacent boards (see below). Ensure the stave ends
on adjoining boards are no closer than 80mm and header (board end) joints are no
closer than 250mm. When tapping Clips into the new board, take care to ensure they
are no closer than 50mm to the Clips on the last row.
To lay subsequent rows of boards, fit the Clips as before and offer the tongue and
groove together. Using a wooden block, (or installation kit for 14mm floors), gently
tap the joint together, working evenly along the board, taking care not to put weight
upon the new board until the joint is nearly closed. Moderate downward pressure
will then push the Clips home. With some types of Clip it is normal for there to
be small gaps between the boards.
The last row of boards will probably require cutting to width to fit. This row is
glued along the tongue and groove joint only if a Clip cannot be fixed and is the
only board to be glued this way. Do not forget to leave the appropriate clear expansion
gap. Use a joint puller to fully close the joint (see below).
Finishing the job
Remove all temporary wooden spacers at the perimeter.
EDGE DETAILS AND OTHER TIPS
1. The Perimeter Gaps can usually be covered with Junckers skirting, scotia or quadrant.
These are usually nailed, screwed or glued to the wall or existing skirting. Large
installations such as sports halls, due to the relative size of expansion gaps,
may require special section skirtings or cover-strip edge details.
2. Radiator Pipes Drill a hole in the board to accommodate the radiator pipe. The
space around the pipe must be the same as the expansion gap at the wall (see below).
A tapered wedge is then cut from the board as shown and this is glued back into
place after the board is laid. The gap around the pipe is then covered with a Junckers
radiator pipe cover, available in hardwood or plastic.
3. Door Frames and Architraves The boards must be fitted under door frames and architraves,
allowing the appropriate expansion gaps. Use an off-cut of flooring plus underlay
to make the cut at the correct level (see below).
4. Door Thresholds An expansion allowance will usually be necessary. Where levels
do not change, the gap can be covered with a Junckers Threshold Strip in hardwood
or polished brass. Where levels reduce, a Junckers Ramp section may be suitable.
To ensure the expansion of the floor is not restricted, ramps are best fitted to
the edge of the Junckers boards and not the sub-floor. The ramp can be supported
by hardboard or ply instead of underlay if the underlay is 2mm or thicker. This
would also apply to junctions with mat wells. Floors over 12m wide, or those in
irregularly shaped rooms should be laid starting from the centre. A special Double
Clip is available and is used with a loose tongue which is glued to one side (see
below). These methods are also useful for floors which are laid diagonally or where
changing the laying direction.
MATERIAL SELECTION
Junckers Floors are graded in accordance with established criteria. However, it
must be expected that for certain grades of flooring, the laying process will include
some on site filling, selection and making good. Factory filling may not always
provide a perfect result as it may become dislodged during the handling and laying
process. Junckers are able to provide tubes of filler for this purpose. As a general
rule, most floors will require a 3% allowance for cutting and selection.