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Plywood Is Better Substrate To Glue Vinyl

Jim Coulson on adhesives – Part 2

I WROTE about using Diamond Marked plywood and the desirability of making sure that your wood-based substrate is of good quality and is therefore suitable for sticking floorcoverings onto. (CFJ November 2013)
Last month I explored the potential problems which may arise, if your chosen adhesive is not compatible with the wood-based substrate that you may have decided to use (‘cheap’ plywood, for example).
But what if you are not in control of the specification for the substrate, but you are nevertheless being asked to bond a floorcovering onto something which neither the floorcovering manufacturer nor the adhesive manufacturer approves of – and maybe even perhaps will not warranty?
Well, coincidentally, I had just such a case come to me, just after my Diamond Mark article was published.
A flooring installer wrote to say that a client – a manufacturer of modular buildings – was using either chipboard or OSB for floors, and was insisting on the installer gluing a vinyl onto those substrates; whereas the vinyl manufacturer would only approve it if it was glued onto plywood.
And – as I warned you in Part 1 of my adhesives article last month – chipboard and OSB can have very different characteristics from plywood, when it comes to accepting things glued onto them.
Chipboard can be prone to moisture absorption and swelling if a water-based adhesive is used; and OSB has a more uneven surface, caused by its very make-up, than a smooth plywood will have.
But even allowing for the use of a solvent-based adhesive or one which may have a degree of gap-filling properties and which can, to some extent, ‘level out’ any unevenness in the substrate, there is also the issue of ‘moisture resistant’ grades of board being used.
These – especially chipboard – may contain waxes or other ‘waterproofing’ agents that can upset the adhesion properties of your preferred glue; and then either or both the adhesive manufacturer or the floorcovering manufacturer may not give a warranty for the final work.
In such a case, my preferred solution would be to change the substrate to plywood; since it is more stable than chipboard, it is more ‘even’ than OSB, and it normally contains no waxes or other ‘waterproofing’ substances that could upset the glue.
But with my enquirer, their ‘modular building’ client has apparently refused to consider the use of plywood – either as the original flooring material, or as an overlay onto the chipboard or OSB – and yet is insisting on there being a warranty on the finished flooring.
I can understand the reluctance to change to plywood, since that will very likely increase the cost of the finished buildings: but then to insist on a particular floorcovering and a particular adhesive, when apparently neither manufacturer is prepared to warranty their use in those circumstances, strikes me as unfair, to say the least.
So what is the answer? I have offered my help, to try to persuade the building manufacturer to either change the specification, or to conduct some trials in conjunction with the adhesive manufacturer and/or the flooring manufacturer to see if a warranty could be offered after all: but I certainly would not advise the flooring installer simply to ‘carry on regardless’.
Jim Coulson is Director of TFT Woodexperts, based in North Yorkshire
T: 01765 601010
www.woodexperts.com

This article has been reproduced from the Contract Flooring Journal website. You can find them at www.contractflooringjournal.co.uk.