BEFORE SELECTING A SOLID NATURAL WIDE BOARD PRODUCT YOU NEED TO BE PRODUCT AWARE
Timber is a natural product and expands and contracts depending on seasons, humidity, heat, direct sunlight, wind and just the natural movement caused by the timber grain dynamics in each individual timber board. The level of movement can vary between any or just one part of your product and also varies between the species of timber, Australian Hardwoods being the most prone to movement. Whilst in most cases no or little movement occurs this cannot be guaranteed and is the maintenance risk the client is taking selecting a wide board product. With wide board products ‘NO WARRENTY’ is given for movement, splitting, shrinking or buckling as this cannot be controlled with a “SOLID WIDE BOARD PRODUCT” and you must be aware this is part of the Natural product
selection maintenance you may have to address throughout the life of the product.
How to limit movement:
While a solid ‘wide board’ product visually may be desired by our clients and is widely preferred, it is a product that is not covered by warranty for the movement noted above. Alternatively a ‘laminated product’ can limit movement. A laminated product is not to be misunderstood for a “Veneered product”. A laminated product is still a solid timber product although glued up with multiple small sections of the solid timber selected. Laminated products eliminate the natural grain movement within a solid wide board and in most cases if movement did occur it would only be a fine
hairline movement in glue joint. A veneered product is not used by OZStair unless curved sections are required.
If the client prefers/ elects to take the maintenance risk of a solid wide board product then the following will help limit movement:
- The top and bottom of all timbers to be painted or polished to seal both sides to limit this movement – This is not part of OZStair works and must be performed by a painter and it is recommended to seal the timber as soon as it is installed including areas not seen. This WILL not stop natural movement but will aid in reducing environmental impact
- Do not install hot water heaters, exhaust fans, lighting under staircase areas. These WILL in most cases cause problems
- Floor heating and air-conditioning – This WILL impact the movement of a natural product
- Windows in staircase areas – Direct sunlight or heat from a window “WILL” have an effect on your natural timber product
- Staircase exposed to sub floor areas- Staircases should be sealed/covered or fully enclosed
Questions often asked:
- Why has the movement only occurred in one or a few of the product parts – Each individual timber product has its own timber grain dynamics and will react differently in a given environment or situation.
- Why has this only occurred in the landing or winder turns – When timbers are glued up into a large section each board within that wide board glue up reacts differently and the effect can be multiplied. This cannot be controlled with wide board section although in most cases it is successful although is the maintenance risk of selecting a natural wide board timber
- Why has the landing or winders come apart at the glue joints – All board are glued using industry recommended adhesives and joints are also biscuit joined together. This though still remains the ‘weakest’ part of the large board section and if movement occurs it will take effect usually along the weakest point ‘being the glue joint’. This is not a glue joint failure rather as mentioned above the timbers natural movement that cannot be controlled.
- Why does it look like the grain is separating – This is the natural shrinkage of timber that may or may not occur over the lifetime of product
- Why has fine cracks along walls or edges of painted stringers occurred – This can be generally 2 things:
- In most cases with timber framed houses the timber studs in the walls shrink and this will cause fine cracks down corners of walls along timber skirtings and also around the boarders of staircase timbers to wall and floors. This is usually addressed by gap filling but it also can cause the staircase to move/rub on walls. This can be addressed by tightening all the wall fixings under the staircase and pulling the walls tight to staircase again. All are maintenance risk of the natural product selected.
- Also the natural timber staircase product has shrunk or expanded naturally and pulled timbers away from walls or floors – This again can be addressed as a maintenance issue with a natural product
- How come the timber floors haven’t moved but the staircase timbers have- Timber flooring is a narrow and thin timber board product and therefore has less movement. The natural grain dynamics in flooring have been reduced by making it into a small timber sections. There is clear Australian Standards regarding 22mm timber flooring products and the amount of movement generally acceptable. With staircase timbers the solid timber product is a full width timber product across the width of a tree and has a greater width from 32 to 42mm. There is no Australian standard governing movement in staircase wide board products because it cannot be controlled or have a standard as each section of timber reacts differently. This is the purpose of this product care document to make our client aware of the product they are selecting.
OZStair has a strict policy of only sourcing our material from reputable timber suppliers who test for correct moisture content this though cannot control environmental impact. Slight gaps may appear to newel posts, landings, treads etc from time to time and may close again. These are not considered a defect but a stabilization of the material or reaction of the material in an unstable environment.
A common maintenance required by the client when gaps may appear is to put a colour matched expandable caulking material in the gap, so if the material continues to move the caulking material will move with it. By placing hard putty in a gap it will crack and breakout if the material continues to move.
OzStair uses Guide to Standards and Tolerances which was produced in collaboration with the Victorian Building Commission, the Office of Fair Trading NSW, the Tasmanian Government and the ACT Government in 2007. This identifies what is considered acceptable movement in timber. A copy of the Guide to Standards and Tolerances is available on your request.