Junckers Wooden flooring installation guide

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 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.