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Water – The ‘Achilles Heel’ Of Wood

Jim Coulson on water – the ‘Archilles heel’ of wood

IN my nearly 40 years of working as a timber consultant, at least 50% of the problems I have dealt with had something to do with moisture in wood. And in about half of those cases, the moisture – usually in the form of leakage or water penetration – has got into the wood after installation, when the moisture content of the wood had originally been OK at the time it was delivered or installed.
And with regard to water, flooring is no different to wood used in general construction: issues can happen when water gets into the timber – that is the one ‘Achilles Heel’ of this excellent and versatile material. And yet, avoiding major problems with water penetration or moisture absorption is not really that difficult – you just need to think a bit!
There are a number of things that you can do to minimise problems when doing a job – even before you begin to lay the wood flooring or the wood-based substrate (such as plywood) for an overlay. But that means applying common sense, before simply ‘getting on with it’.
Let me give you three examples from my past experience, and you’ll see what I mean.
1. Be more aware of the environment. Is it a very hot and dry building – such as a retirement home, or a hospital? Nothing dries out ‘normally dry’ timber more quickly than a very dry, heated environment.
I have come across excessive gaps in flooring blocks, or floorboards – and even laminate floors are not totally immune to some movement (although they do resist temperature and humidity changes better than solid wood flooring can), where severe moisture loss has occurred to the wood after fitting.
2. Check your product. Don’t trust it to be necessarily at the right moisture content for immediate laying (I have written before about the need for a good moisture meter!).
Solid hardwood flooring is particularly prone to being shipped in a very, very over-dry state – especially imported American stock – and so it can (and believe me, it will!) expand and then ‘hump’ the whole floor, as it absorbs atmospheric humidity in its new environment, as soon as it has been removed from its vapour-tight wrappings: I have seen it happen many times.
So remember to ‘condition’ the flooring by unwrapping it and leaving it for a week or so in the room in which it is to be finally fitted. (What is that you’re saying? You have no time to do that? Then you must expect problems! However, having a word with your client and asking if the flooring can be delivered a few days prior to the commencement of the job, can usually be arranged – provided you plan ahead.)
3. Check the condition of building. Old buildings – particularly those with any history of dampness, or even past flooding (remember the last winter) – can hold onto excess moisture for a long time: and that will (I guarantee!) find its way into the ‘new’ wood of your plywood overlay or your nice new timber flooring products.
In one memorable case, I was investigating a building (it was a bar and night club) very near to a riverside, where there had been flooding from a nearby river, about six months before; and a new Maple dance floor had just been fitted.
Half of the floor area was OK, but the other half had ‘humped’ because the Maple strips had expanded quite severely: But the flooring contractor assured me that he had checked the moisture content of the flooring and it was suitable for the environment into which it was being installed.
So then I checked the building. Underneath the ‘good’ half of the floor, there was a concrete screed, which was dry: but beneath the ‘troublesome’ half, there was an old, suspended timber floor. I found this to be at a very high moisture content, as were the undersides of the recently-fitted Maple strips: and so I investigated further, and discovered a trapdoor.
As soon as I opened this trapdoor, I then found an old cellar, directly beneath this ‘troublesome’ half of the old floor – and lo and behold, the cellar had a lake in it! (It was still harbouring umpteen gallons of floodwater: and this was now migrating up into that nice new Maple flooring.)
So my point here is: wood is a wonderful material, which performs lots of jobs well and looks great: but it is – and it always will be – susceptible to losing or gaining excess water. So please use a bit of ‘common sense’ and all should be well (though I’m keeping my fingers crossed!).

This article has been reproduced from the Contract Flooring Journal. You can find them at