Neal arrived onsite to find Freddie’s newly-laid LVT floor was failing dramatically – lifting and buckling like a soggy old trampoline skin. But it wasn’t an adhesive failure this time. So what could possibly have caused it?
THE phone was squawking off its cradle… funny how the panic calls seem to sound different.
‘Ahhhh… Freddie, another problem huh? Oh dear. Ahhh, only halfway through a job and it’s all going wrong.’
‘I see a newbuild, first floor, LVT installation, a chipboard decked floor onto a joist …right… so the first stage is buckling, bouncing, and flopping about?’
Didn’t sound like a moisture issue, but I didn’t want to give Freddie the Flooring Contractor too much hope. Now early versions of chipboard were a homogenous, uniform material coming in 8×4 sheets and square edged to be butt joined.
The starting material is much like a saw-dusty porridge, sort of a version of soggy Weetabix. It’s mixed with an adhesive and extruded out as a much thicker ‘mattress’. The finished product is then formed under heat and pressure and squished to the almost correct thickness, the final treatment being a sanding to get it to the thickness as advertised, producing a nice smooth surface.
Improvements in particleboard manufacture these days puts a layer of very fine material to form the upper and lower faces, laid down to give a dense surface, and bliss: accurately machined T&G edge and ends.
The product offers huge advantages in speed of installing a floor deck, with little need to cramp up as would be needed with traditional T&G floorboards. Accurate machining means correctly set out, the floor deck joints are drum tight.
BUT, and of course there’s always a but, this material is STILL a wood-based product, albeit in a fine structure. In moist conditions the chips/particles will still swell and expand. Just leave an offcut in the garden for a few weeks and watch it return to Weetabix.
So to overcome this the manufacturers coat the faces with a waxy-type treatment to give a temporary shower proofing. I also believe this coat helps as a release agent in the pressing manufacture. You all know how slippery new sheets can feel.
This is why chipboard needs to be overlaid with ply, to achieve a proper adhesive bond for tiles and resilient flooring.
Now dear reader, this is where we get to the reason for my visit. I arrived onsite where Freddie’s newly laid LVT floor was failing dramatically – lifting and buckling like a soggy old trampoline skin, but it wasn’t an adhesive failure this time. So what could possibly have caused this?
Bit of a hint: there’s young Rodney, all bullish, swaggering across site like John Wayne, trailing his airline and menacingly swinging his coil air-nailer. He was festooned with strings of collated nails around his neck, like the wild eyed machine gunner in a particularly graphic Vietnam war movie (hey, we’ve all done it!)
So how many fixings to securely fix a ply sheet? Oddly enough, one or two per sheet just didn’t seem enough, so cleverly the boffins at BRE and the equally clever lads at British Standards worked out you need edge fixings at every 100mm, then every 150x150mm as a grid across the body of the sheet, cos that will PROPERLY fix it.
The absolute ideal is that the screw/nails head are embedded only just below the surface of the ply. This way the full compression characteristics of the fixing head is being applied to the whole surrounding halo on the ply, to ensure the tightest fix possible.
Great so far? You’d have thought so. However Rodney got into his head that the more fiercely those old fixings get powered into the ply, the better. Y’know, like just to ensure the wily enemy stays well and truly dead. So he’s wound up the pressure setting to max!
Regrettably, Freddie didn’t spot this, but the wild enthusiasm of an apprentice to get on with a task so willingly, should’ve been a bit of a giveaway. This combination of pretty rubbish ply and a high-pressured nailer drove the ring-shank nails almost all the way, if not actually right through the sheet. The holding capacity? Well, predictably, practically zero, hence the ply lifting free from the subfloor, undermining the technical bods hard and careful research work.
Gods preserve us if young Rodney ever gets his sticky paws on a Hilti gun – being even more realistic, this fires a PROPER charge propelling the nail like a REAL bullet. Thank goodness you now need to be certificated to use one. This didn’t used to be the case.
‘So where did you source the ply from, Freddie?’
‘Yeah, well, I bought a load of cheap 6mm from my mate, Barry.’
It looked like Barry had cobbled it up over a weekend, at night in his garage. Typical of Freddie to buy this cheap non-spec rubbish, rather than using a proper flooring grade ply such as HSP 101.
I left Freddie mournfully totting up his small savings on the ply, versus the significant rip up and replacement costs.
The next weekend I saw young Rodney, looking ‘well ‘ard’, sauntering out of the latest Rambo movie, cultivating his ‘thousand-yard stare’ like, hey, I’ve been there man!
Bless him…
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