Properties Of Wood
Jim Coulson on the properties of wood
IN this series in CFJ, I have written about plywoods for overlaying old floors; and about chipboard and hardwoods used as flooring materials. But so far, I have not really gone into much detail about the different wearing properties of wood, when it is used as a flooring material in its own right.
(Of course, the reference should be ‘woods’ since not all timbers are the same, when it comes to their suitability for floors.) And also not all floors are the same; since the amount of wear which any one floor may get, will depend on its use: either for domestic, or for ‘light industrial’ or ‘heavy industrial’; or for a dance floor, or even a stage in a theatre.
What I am saying is that not every timber will be suitable for every use: and therefore not every timber used as flooring will necessarily be suitable for every type of floor. Softwoods such as European whitewood (Spruce) are commonly used for domestic floors (as an aside: almost everyone calls them ‘Pine’ floors, but most domestic suspended timber floors these days are made of Spruce rather than Pine.
So that is simply an appearance issue, rather than a matter of how they will wear in use). Of course, hardwoods are used, albeit less frequently these days, for the more decorative floors. Last month, I explored some of the alternative species of hardwoods available.
Rock Maple (sometimes called ‘Hard Maple’) is used for dance floors and also for some sports, such in as squash courts and tenpin bowling alleys, but apart from the species of timber, what other factors are there which can help to make any floor ‘wear’ better?
One of the most significant factors is the orientation of the growth rings: in other words, how the timber is laid, relative to the plane of the floor’s surface. Let me explain…
We all know that timber has ‘growth rings’, usually relating to the tree’s age. But what many people do not realise is that when timber is cut ‘flatwise’ across the log, the growth rings come to the surface at a very shallow angle and the timber, as a consequence, wears more unevenly and so does not last as long.
But if the log is sawn so that the growth rings strike the surface of the floorboard at a steep angle (known as ‘quarter-sawing’) then the wearing characteristics are much improved: as much as double the life can be achieved.
The downside is that such boards are considerably more expensive to produce; but the upside is that they are more ‘stable’ in service and do not shrink or ‘move’ as much as flat-sawn boards do.
Finally, and much less well-known than either of the above, are so called ‘end grain’ blocks. As the name suggests, the timber is cut in the direction across the log; and the blocks which are used as the floor deck have the growth rings pointing upwards, so that they are visible as ‘semicircles’.
This is both interestingly decorative and very hard-wearing. But the downside of this particular ‘cut’ is that the blocks are much, much more prone to moisture movement, if their installation is not specified or installed correctly (see the picture accompanying this article). Nevertheless, for a good, hard-wearing floor surface, this type of ‘grain orientation’ is well worth thinking about.
This article has been reproduced from the Contract Flooring Journal website. You can find them at www.contractflooringjournal.co.uk.