Scope
Information Sheet AI1 describes installation procedures for Particleboard Flooring in generally domestic applications. This sheet is concerned with flooring installation in wet area rooms: bathrooms, laundries and toilets, and particularly shower recesses. As with AI1, the information applies specifically to Particleboard Flooring applied over a system of joists. It applies to Standard Particleboard Flooring or to fungus and termite resistant Flooring and Fire Retardant Flooring (designated "F", "H2" and "FR" respectively).
Wet Area Rooms
Wet area rooms are those where water spillage is likely on a regular basis (eg daily or weekly). Bathrooms, laundries and toilets are usually considered to fall into this category. Kitchens may also be thought of as wet areas since dishwashing machines may overflow from time to time. This matter was considered by Committee BD/38 (Moisture Barriers in Buildings) of the Standards Association of Australia. The Committee decided that kitchens did not represent a big enough risk to be included in the classification.
PARTICLEBOARD FLOORING
Selection
Particleboard Flooring should only be used in wet area rooms if there is no risk of leaks allowing water to reach the Particleboard. If it is considered that there is a risk of short-term dampness, Particleboard Flooring F should be used. Please note that no Particleboard Flooring will perform satisfactorily if continually wet. Fungus resistance provides protection until the cause of dampness can be found and fixed. Particleboard Flooring H2 is available for areas with high termite activity and FR Flooring is available for areas where improved Indices of Early Fire Hazard are specified.
To avoid the risk of water reaching the Particleboard the following construction features should be present:
1. Bearers and joists should be dried or stabilised. Shrinkage of green bearers and joists can lead to breakdown of flashing and sealing.
2. A precast shower base or shower tray should be used. In-situ construction using rubber-type sheet or strip flashing or sealing membranes do not provide the necessary assurance.
Installation
The selected Particleboard Flooring is fixed as specified in Information Sheet Al1 using mechanical and adhesive fastening. Particleboard is installed as platform or fitted floor.
SEALING & FLASHING
Room Perimeter
The perimeter of wet area rooms should be sealed with a rigid PVC angle flashing 50 x 100 to 150 mm in size. The flashing must be fixed before wall lining (plaster board or fibre cement sheet) is applied, so that the flashing finishes behind lining sheets - see Diagram 1.
The angle flashing is glued to the floor (50mm side to the floor) using Particleboard floor adhesive or a 2-part epoxy. Consult Particleboard manufacturers' literature for approved adhesives. PVC angle flashing should not be fixed to bottom plate or wall studs, so that any subsequent movement of the timber frame will not break it. However to ensure the flashing remains in place, a clout head or adhesive spot should be used at each stud to provide a temporary restraint.
Board Joins
Board joins should be flashed with a strip of rubber-type sealer, 130-150 mm wide. The sealer is glued with 2-part epoxy adhesive with precaution taken to leave a 25 mm section unadhered down the centre. This is achieved by using masking or packaging tape as illustrated in Diagram 2. The purpose of this unadhered section is to take up any slight sheet movement at the join.
If a mortar bed is to be laid over the sheet join, wire reinforcement should be used (see Diagram 1). Reinforcement should be 150mm strips of galvanised birdwire or a manufactured product such as Boral Brickwell. Place reinforcement centrally over the join and hold in place with staples or nails.
Shower Trays and Bases
Precast shower trays and bases provide the best assurance of watertight shower recess construction.
Shower Tray - preformed tray made from copper, stainless steel or fibreglass. These should be used when ceramic tiles are to be fixed to form the finished shower floor.
Shower Base - precast ceramic or polyester (Polymarble) base intended to form the finished shower floor.
Trays and bases should usually be fixed before the wall sheeting which then runs down into the tray or onto the base edge recess, according to manufacturers' instructions.
Shower trays and bases should be bonded to the floor surface with adhesive or mortar according to manufacturers' instructions. Care should be taken to ensure that the tray is properly supported on the base and sides, otherwise the weight of workmen or house occupants will cause distortion, movement and possibly fracture.
A properly installed, precast shower tray or shower base should provide the basis for a leak-free installation and allow Particleboard Flooring to be used in wet area rooms.
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Wall Corner
PVC, fibreglass or flexible strip flashing should be fixed to the shower recess wall corner before wall sheeting is installed. Corner flashing should run down into the shower tray. If a shower base is used, it will run to the recessed edge - see Diagrams 3 and 4.
In-situ Shower Trays
In-situ trays may be made from sheet metal (copper) by a tradesman plumber, from flexible rubber-type membrane or from fibreglass matt plus epoxy resin.
Site-made copper trays should be satisfactory but are at higher risk from building movement than factory-made trays. Factory made trays should use a folding process for corners, which are watertight but allow some movement. Braised joints may fail from forces generated by wall and floor movement.
Particleboard Flooring F should be used for wet area rooms if in-situ tray construction is to be used.
Flexible membrane trays are made by gluing flexible membrane over the shower recess floor and then bonding strip membrane material around the shower recess perimeter. This material should be cut from metre-wide sheets so that a one-piece installation results over the shower recess floor. Details of corner strip and floor sheet bonding are shown in Diagrams 3 and 4.
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Hob Construction
A hob is the site construction (usually of bricks) to complete the fourth side of the shower recess. It provides the entry, and is the base for a sliding screen door if such is being used.
With shower trays, bricks should be set inside the tray edge so as to retain water inside the shower recess. A better system is split brick - bricks are cut in half with each half being laid on either side of the tray edge. However tradesmen do not usually have equipment available for split brick construction.
With in-situ trays, care is needed to provide adequate sealing at the hob ends (ie. where it joins the wall) and along the hob length. Rubber membrane trays should have the rubber turned up and bonded to the outside of the hob. Alternatively a length of rigid PVC angle flashing can be glued in place and the hob laid inside this. Care must be taken to avoid damage to the PVC angle between installation and laying the hob.
Careful attention to detail is needed generally because the shower recess screen or curtain will ensure a steady stream of water down onto the hob and to its corners. The corners are common sources of leaks.
Floor Wastes
When holes are cut in Particleboard Flooring sheets for any service pipes, all edges of the hole should be sealed with epoxy adhesive. A PVC flange should be used for the waste pipe and the flange should be bonded to the Particleboard surface (or shower tray) with epoxy adhesive -see Diagram 5.
Ceramic Tiles
Before laying a mortar bed for the fixing of ceramic tiles, the Particleboard surface must be sealed. An epoxy sealer is recommended which must be tacky when the mortar bed is placed. It is unlikely that proper sealing of the Particleboard, and a tacky surface for mortar bonding, will be achieved with one coat of epoxy. The first coat should be brushed on and allowed to dry. Apply the second coat just before laying the mortar bed.
Prepare and lay the mortar bed (usually 3 parts sand to I part cement). Slope the mortar to floor drain where one is required by local authority; typical slope is 1 in 80. Slope the mortar to shower recess drain, usually 1 in 60. Follow Building Regulations regarding minimum mortar bed thickness, this may be as low as 12 mm in some states but a thicker minimum, say 25 mm, is recommended.
It is common practice in some areas to seal shower recesses with a fibreglass system - liquid resin to seal corners, drain and hob plus fibreglass mat for reinforcement. It can be difficult to obtain good bonding between the set fibreglass and the mortar bed. A roughening or etching of surface is necessary to avoid later "drumminess".
Health & Safety Information
Normal health and safety precautions should be taken when working with wood panel products. Machine tools should be fitted with dust extraction and work areas should be kept clean. If dust levels exceed The National Occupational Health & Safety Commission's standards, the wearing of a dust mask (AS/NZS 1715 and AS/NZS 1716) and safety glasses is recommended.
Storage and work areas should be adequately ventilated. If large quantities of Particleboard are stored in non-ventilated areas, formaldehyde emissions could accumulate to levels that may irritate some people.
For further information, please contact one of the manufacturers listed below for a Material Safety Data Sheet or download from www.woodpanels.org.au .
Whilst the information contained herein is based on data which to the best of our knowledge is reliable and accurate as of the date hereof, no responsibility can be accepted by us for errors or omissions. Since the information contained herein may be applied under conditions beyond our control, no responsibility can be accepted by us for any loss or damage caused by any person acting or refraining from acting as a result of this information.
Published by the Australian Wood Panels Association Incorporated, PO Box 158, Coolangatta Qld 4225, September 2001 |
