Scope
This information sheet covers the installation of Particleboard Flooring in housing applications. The information and procedures also apply to Particleboard used as flooring in other similar applications; that is, where the particleboard is applied over a system of joists and will be subjected to loads not greater than 4 kPa Uniformly Distributed Load or 2.7 kN Concentrated Load.
Particleboard Flooring is also available with fungus resistance, termite resistance or fire retardancy (designated "F", "H2" and "FR" respectively). These products are intended for use in applications where there is a risk of attack from one or other of these wood destroying agents. Installation methods are the same for standard or treated Particleboard Flooring.
Installation of Particleboard Flooring in Wet Area Rooms is covered in Applications & Installations Sheet AI2.
Site Storage
Particleboard Flooring is usually installed using the platform method of construction, and is designed to withstand full weather exposure for up to 3 months. There is a tendency to leave flooring packs unprotected on site since the product will resist moisture. However packs must be protected from the weather until the particleboard is installed. Moisture will cause expansion and this will lead to gaps in the floor later when the particleboard sheets dry out.
A good quality job requires board packs to be protected from the weather until the sheets are installed.
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Good site storage is essential |
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| Correct Method for sheet layout and nailing |
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Subfloor Ventilation
When any timber materials are used in a ground floor system, adequate ventilation must be provided. Poor ventilation will allow moisture build-up in the timber materials which may eventually lead to failure through fungal attack. Particleboard behaves in a similar way to other timber products and requires cross-ventilation in the subfloor space by means of openings in the substructure walling. Ventilation areas required by Local Authorities should be used.
I n cavity masonry walls, the openings required for ventilation must be provided in both leaves of the masonry, with inner-leaf openings directly opposite outer-leaf openings.
One ventilation brick per metre of wall length provides about 7500 mm 2 ventilation which is usually regarded as the minimum requirement. Ventilation should be evenly spaced along the wall length with particular care being taken to ventilate internal corners.
If internal walls are constructed in subfloor spaces, ventilation opening should be three times the figure above ie. about 22,000 mm 2 per metre.
The clearance between ground surface and the underside of the particleboard sheet should also comply with Local Authority requirements; 350 mm is the minimum clearance recommended.
Subfloor Framing
Bearers and joists should be placed and fixed according to good building practice. Top surface of joists must be level to allow particleboard sheets to lie flat and level. Kiln dried or stabilised subfloor timbers will usually result in a better finished job.
Joists should be spaced at 450 mm or 600 mm to suit the Particleboard Flooring thickness. The economic advantages of platform construction are greatly enhanced by the use of roof construction (ie. Roof trusses) that allows non-load bearing internal walls. Non-load bearing internal walls can be placed anywhere on the particleboard platform floor without any additional support. However load bearing internal walls must be supported by a joist or trimmers under the bottom plate.
INSTALLATION
Sheet Layout
Sheets are laid with the long length across floor joists with ends butted over a joist. Sheet end joints are staggered as illustrated in the diagram. Set a string line at the ends of joists, parallel to the perimeter of the building and at right angles to the joists. Position the first sheet with its tongued edge to the string line. Ensure that information printed on the sheet is followed to give the correct top surface.
Each sheet must be supported by at least three joists.
Fixing
Particleboard Flooring should be fixed with construction - grade adhesive and mechanical fasteners.
A bead of adhesive is applied from the cartridge applicator to joists before positioning particleboard sheets. The bead should be 5-6 mm across and must not be laid too far ahead as it may cure quickly. The adhesive bead must not be allowed to dry and become hard on the surface. The open time available will depend on weather conditions which may restrict advance adhesive application to the amount required for one sheet only.
Adhesive fixing provides a stiffer floor, and an extra bead along the tongue before sheets are pressed together will ensure a squeak-free floor system. Any excess glue squeezed out should be cleaned off.
When sheets are cut on site, the cut edge should be sealed with adhesive.
Nailing
Nails should be spaced at 150 mm centres along sheet ends and at 300 mm centres over the rest of the sheet (refer to Diagram). Nails should not be placed closer than 10 mm to the base of the groove along the long edges. This gives a minimum edge nailing distance of 25 mm for the long edges and 10 mm from the short butt joined ends.
Nails may be applied by hand or by nailing gun. With gun nailing care should be taken to adjust air pressure for softwood or hardwood joists, so that nails do not penetrate the surface by more than 1mm. Do not allow nails to pull the board to the top of the joists - the fixer should use his body weight to ensure that the underside of the sheet is in firm contact with the joist before firing the nail.
Use 50 mm x 2.8 mm galvanised nails for hardwood or cypress pine joists and 65 x 2.8 mm galvanised nails for softwood joists. Nails may have Bullet, Jolt, Flat or Countersunk heads, however Bullet or Jolt head nails should be skewed to improve holding power. Nails should be driven flush initially and not punched until immediately prior to sanding.
Power driven nails should be 55 x 2.5 mm Tee Head or Finishing Head for all timber joists. Use only galvanised or rust-resistant nails.
Metal Joists
Construction adhesive and extended point self-tapping screws (e.g. No 10 x 45 mm CSK from W. A. Deutscher or similar) are recommended. Screw spacing is the same as specified for nailing.
CONSTRUCTION
Platform Flooring
Methods described generally apply to Platform Construction. Although an exposure period of 3 months maximum is permitted, efforts should be made to protect Particleboard Flooring from excessive exposure. Any ponded water should be swept off. Drain holes can be provided by drilling in places or skirtings. Roof cover should be provided as soon as possible. Excessive and differential drying can be caused by the hot Australian sun. This may result in cupping which could, in extreme cases, cause nail pull-out or pull-through of nail heads. In very severe cases, shading may be needed, or alternatively, water should be sprayed onto the Particleboard Flooring surface to recondition sheets back to uniform moisture content.
In general, attempts should be made to keep the exposure time to a minimum.
Damage may also be caused by other tradesmen and attention is needed to avoid:
. wet trades using the floor as a mixing table
. excessive spillages of paint, plaster, concrete etc
. stacking of heavy materials such as bricks, cement bags, sand.
Fitted Flooring
Fitted floors are those installed after internal walls are constructed and usually after the roof and wall claddings are fixed.
Fixing is basically as described. An expansion gap of 10 mm should be left around all walls. This gap will later be covered by skirting boards.
Finishing
Particleboard Flooring will usually need to be sanded prior to finishing or laying of floor coverings. However for carpet installation sanding may not be needed if the surface layer is smooth and sound.
Before sanding, the floor should be dry and nail heads should be punched below the surface. Sanding should not remove more than 1 mm of board generally or 2 mm at board edges.
If carpet is to be laid, a light sanding with 40-60 grit paper may be all that is necessary, if building trades have not left paint, plaster or cement on the floor. If a clear finish is to be applied, the 40-60 grit paper sanding should be followed by fine sanding with 80-100 grit paper.
Clear Finishing
Particleboard Flooring can be clear finished with polyurethane to give a cork-like appearance. However some colour variation between sheets is to be expected and construction activities and weather may contribute to colour variation. Particular care is needed to avoid staining, discolouration, surface damage and distortion - see "Construction" section. For these reasons a tint or stain may be an advantage in the clear finish.
After sanding fill all nail holes with appropriately coloured putty and apply the clear finish to manufacturers' instructions. Three coats are recommend.
Resilient Floor Coverings (Vinyl)
There is a very wide range of resilient floor coverings, usually vinyl sheet or tiles. Installation procedures must follow manufacturers' instructions carefully, especially with regard to adhesives and underlayments.
Particleboard Flooring can be used for resilient floor coverings without underlay. However it is not possible to give a general recommendation on this matter. During exposure of platform floors to weather conditions, some movement must occur in both the thickness and the plane of Particleboard sheets due to swelling and shrinkage. This movement may lead to small gaps between sheets. It is thus not possible to guarantee that sheet edges and nail holes will not show through soft, flexible floor coverings.
In general an underlayment is recommended. Special inspection is needed before an individual installation could be approved for vinyl flooring laid directly onto the Particleboard.
Ceramic Tiles
Ceramic tiles should not be laid directly to Particleboard Flooring. An underlay of 6mm fibre-cement sheet should be used, fixed according to manufacturers' instructions. Underlay sheets should be sealed before application of adhesive or mortar.
Manufacturers' instructions should be followed for all details of ceramic tile installation.
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 or MDF 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 |
