Metal Fixings & Fittings
General Advice It is important to follow the recommendations of the manufacturer of any metal products used for specific advice regarding suitability, desired service life expectations and particular exposure conditions. Tanalith E pressure treated timber has a long life expectancy and it is appropriate to use metal fixings and fastenings that will have a comparable length of life.
- Performance of metal fixings is influenced by the environmental conditions including moisture content, temperature, atmospheric pollution, proximity to coastal locations, timber species, as well as the thickness of any galvanising.
- For exterior use, where the timber is likely to become wet and a long service life is required, greater corrosion resistance will be achieved with use of austenitic grade 316 stainless steel, silicone bronze or copper in preference to other types of fittings.
- Galvanising provides a sacrificial zinc barrier. It is important that the specifier/end user is aware that there are many thicknesses of galvanised coating available and the thicker the galvanised coating the longer the expected service life. The level of galvanising should be commensurate with the end use. The use of an automated nail gun may break the galvanised layer in lower grade metal fixings and compromise their performance at the outset.
- Electroplated metals only provide a thin coating and are unsuitable for exterior applications.
- It is good practice to drill pilot holes for fixings, in particular when screwing near the edge or end of a piece of timber.
- Attach connectors, fasteners and fittings after preservative treatment and only after the timber has re-dried to less than 20% moisture content.
- In addition to the above, for internal building timbers, e.g. trussed rafters, it is recommended to re-dry the timber to a moisture content of 22% or less before assembly and to maintain the timber in this condition during storage and delivery to site.
- To prevent bimetallic corrosion between fastener and connector components it is important not to mix metals in the same connection. DO NOT mix galvanised and stainless steel components.
- Refer to local guidelines for slating and tiling. Nails for use with slates should be of copper, phosphor or silicon bronze. Nails for use with tiles should be austenitic stainless steel, copper, phosphor or silicon bronze. The use of aluminium and galvanised steel nails is NOT recommended.
- Eurocode 5 (EN 1995-1-1: 2004) gives minimum specifications for material protection against corrosion for fasteners and fixings used in internal building, low hazard situations (Use Classes 1 and 2) where the moisture content of the treated timber will not exceed 20% throughout its service life.
- Direct contact with aluminium should be avoided where the moisture content will exceed 18% or where condensation is possible.
- Where the use of aluminium is unavoidable in situations where moisture content will exceed 18%, it must be separated from the timber using a bituminous, epoxy or other impervious barrier or electrically insulating coating. The use of nylon/plastic washers is recommended.
- Fixings and fastenings used on safety critical and load bearing components should be inspected regularly and replaced if necessary.
- Specialist advice should be obtained in the selection of connectors for use in swimming pool buildings. Detailed advice is contained in the Nickel Development Institute document Stainless Steel in Swimming Pool Buildings 1995.
It is advisable to consult with Lonza Wood Protection using the contact details given in this document if in doubt about any particular area of application or compliance with other relevant standards or specifications. This list below, which is not totally exhaustive, gives an indication of the range of timbers and timber based products which can be treated with Tanalith E wood preservative. The treatment process parameters are varied to match the end use of the timber and its species. It is therefore extremely important that you make sure that the timber has been treated to the correct specification. The use of Tanalith Extra water repellent treated timber may be advisable for certain end use applications, such as decking, cladding and playground equipment.
Building– Structural elements and general timbers in domestic, commercial and public buildings, such as wall frames, sole plates, beams, joists, subfloors, roof timbers, external joinery, battens, cladding, roof shingles.
Garden & Landscaping- Decking systems, pergolas, gazebos, bridges, summer houses, soil retaining walls, timbers around fish ponds (but not in direct contact with the water), playground equipment, lawn edging, fencing, picnic benches and tables, way signs and litter bins. For certain applications, particularly with thin cladding type timbers, it may be appropriate to use a brush-on water repellent or TANALITH Extra treated timber which has a built-in water repellent.
Agricultural & Horticultural- Earth retaining vegetable beds (use of pressure treated timber does not affect organic status), fruit tree stakes, hop poles, vine stakes
Enclosures/Fencing– Natural round, machine turned and square sawn fence posts, rails, droppers, gates and gate posts, stiles and highway, farm and security fencing
Transport– Floors and other timbers for railway and road vehicles, container floors and linings, packing cases, cable drums and hatch covers. For treatments to meet Australian Quarantine Regulations (AQIS) contact Lonza Wood Protection directly for the latest information.
Engineering- Transmission poles, decking, shells, gantries, bridges and bridge decks, handrails, cable ducting and sound barriers.
End Use Considerations
Tanalith E pressure treated timber can be used in internal and external building applications and outdoors, both in ground contact and above the ground, without any need for further protection. Tanalith E pressure treated timber is treated to meet the requirements of a particular end use. When using timber for exterior situations, either treated or untreated, consideration should be given to the propensity of the material to stain light coloured adjacent faces, such as render, paving flags or coated timber surfaces, with its natural extractives during the weathering process. This staining effect can be highlighted where Tanatone treated timber has been selected, although the potential for this to occur does reduce with time. Where used in this external environment, it is highly recommended that contact between the timber and these surfaces is eliminated by design, in order to prevent surface discolouration. Where close tolerance work is involved it is advisable to pre-machine the timber at the in-service equilibrium moisture content prior to treatment. Consultation with the treatment supplier is advised in these situations. When used in construction applications it is always best practice for preservative treated timbers to be dried down to the in-service moisture content prior to fabrication. Treated timber should not be used where it may come into contact with drinking water or for food preparation surfaces/structures or containers for storage. When considering the use of Tanalith E pressure treated timber around fishponds, please contact Lonza Wood Protection for advice. If supplying timber for treatment it is best practice to prepare the timber as fully as possible prior to treatment to ensure best results. If any cutting, notching or drilling is made to the treated timber following treatment, any exposed surfaces should be liberally swabbed with an appropriate end grain preservative to maintain the integrity of the treatment
You should have received the treated timber in a drip-free condition with no sign of preservative fluid on the surface. If this is not the case, the timber should be stored open stacked under ventilated conditions and protected from rain and snow to dry before use. When working with timber, wear gloves to protect the skin against abrasions and splinters. Any cuts and abrasions should be protected by a waterproof dressing. When power-sawing and machining, wear goggles to protect the eyes from flying particles. Wear a dust mask and, whenever possible, perform these operations outdoors to avoid accumulations of airborne sawdust or use a suitable dust extraction system around any mechanical saw or planing machine. Avoid frequent or prolonged inhalation of sawdust. Consult local regulatory authorities for further information on workplace exposure limits for wood dust. In order to prevent injury, care should be taken when lifting or moving timber. These handling precautions equally apply to untreated and treated timber.
After handling or working with treated timber, all exposed skin should be washed before commencing other activities, especially eating, drinking, smoking or going to the toilet. If sawdust accumulates on clothes, clean them before re-use. Launder heavily soiled clothes separately from other household wash items.
All sawdust and construction debris should be cleaned up and disposed following local regulations.
Tanalith E pressure treated timber is not classified as hazardous waste. Local market regulations should be referred to. Tanalith E treated timber and post treatment processing wastes, such as sawdust and offcuts, must not be used for animal litter or bedding or for fuel in barbecues, cooking stoves or grates. Domestic end users should dispose of any waste treated timber, sawdust or ash through the ordinary waste collection service or at a local authority amenity/disposal site. Any waste timber, sawdust or redundant timber from commercial or industrial use (e.g. construction sites) should preferably be recycled by reuse, or disposed of to an authorised landfill or to a correctly controlled and approved waste incinerator.
For further information with respect to Tanalith E, Tanalith Extra, Tanatone treated timbers, end grain preservatives or Restol Wood Oil please contact Lonza Wood Protection using the contact details below. Use biocides safely. Always read the label and product information before use.