Further to our telephone conversation today, here are some of my thoughts about current supplies of plywood
We are a firm of plywood agents representing Brasilian, Malaysian and Chinese plywood suppliers.
A few years ago we were in touch with your organisation regarding the different types of plywood being used in flooring applications, mainly as a substrate prior to overlaying with AMTICO or other vinyl type floor covering. We were wanting to establish if there were any recommendations from CFA to your members for the type of plywood to be used in these applications.
Our experience over many years has been that when solvent based adhesives were used there was less moisture ingress into the plywood and therefore less expansion of the plywood. However, we understand that it is now more normal practice to use water based adhesives which impart even more moisture into the plywood which can cause detrimental expansion resulting in "rippling" of the plywood underneath the floor covering.
Many years ago, most plywood supplied to this market was of Philippine and Indonesian origin with some Malaysian plywood as well and was manufactured from the better quality and more dense timbers from mature "tropical rainforest" trees, however the supply picture has changed dramatically in the last 10 years and in particular over the last 5 years there is a lot of Chinese hardwood plywood sold into the UK market
We wonder if your members are aware of the different types of hardwood plywood available and most importantly the differing densities of raw material from which the plywood is manufactured.
The lower density species from China with a poplar core or some of the lower density Malaysia or Brasilian plywoods manufactured sometimes from a combination of both hardwood and softwood veneers can we would suggest lead to problems for your members when laying expensive coverings on top of plywood that is really less suitable for that application.
There are of course other aspects to this, like "conditioning" of the plywood (similar to hardboard) or recommendations for expansion gaps between the boards, screeding of the boards or nailing centres but at the end of the day, if the wrong type of plywood is used, it can and very often does lead to issues of rippling on the surface or worse still, it can make the plywood delaminate because the expansion can tear the fibres of the timber apart, even although the bonding of the plywood and manufacturing quality of the plywood is satisfactory.
I feel it would be a good idea for you to consider updating your guidance notes to your members to alert them to thinking more carefully about the different options of plywood available today. All hardwood plywood is not the same and if your flooring contractors simply ask their suppliers for "hardwood plywood" they could be disappointed with the performance.
For example, the core of Chinese plywood is usually manufactured with 95% "temperate" hardwood content, usually produced with Poplar species which is much faster growing and of much lower density that the tropical species. The face veneers are usually only 0.3mm thick (or even thinner) prior to manufacture and can end up about 0.2mm after sanding. These faces are no better than a thin decorative veneer and do not have any structural strength, nor do they provide any barrier to moisture ingress into the core. The faces are usually bonded to the core with a Type 1 melamine adhesive and you should perhaps check if there could be some chemical reaction from adhesives used today to bond say vinyl floor coverings as the thin veneers offer little barrier to penetration of chemicals.
Then there are the panels from Brasil, many of which are manufactured using only long grain lamination of tropical hardwood and the cross grain laminations can be made from softwood Elliottis pine species. The face veneers tend to be much thicker than Chinese ply and the glues tend to be WBP Phenolic throughout, so this type of panel should give a more stable performance than the Chinese plywood described above.
These type of panels from Brasil and especially China , can therefore be prone to much greater expansion than a plywood manufactured from 100% more dense tropical hardwood species. These boards have to be conditioned on site and perhaps are more suitable where there is little or no moisture present and certainly are less suitable for new build properties where wet trades have been present.
The current picture of supply of hardwood plywood to the UK market is about 50% China, 40% Malaysia and 10% Brasil but these percentages can change depending on market forces. The Chinese board is usually about 25% lower in cost than Malaysia. Brasil used to be 15% lower than Malaysia but today is 5% higher.
So the market is driven by cost and the most competitive supply options prevail.
My experience tells me that the most suitable substrate panel especially for higher value vinyl projects that your members can specify, must really be the Malaysian tropical hardwood throughout WBP bonded plywood.
A good source of technical information for you on plywood could be TRADA. I do not claim to offer firm technical advise but rather I am coming from a common sense point of view with no axe to grind as we also represent many Chinese suppliers as well. Chinese plywood has it’s place in the constructional market without question, but I know which board I would select for more demanding applications.
i know for fact that timber quality has even been dropping over the last 7 years or so,more and more coming from the Baltics etc.
