engineered T+G floor: seamless plywood vs many separate strips? + underlay

[TofuSpaceship]

Hi all,

we ordered some numbers of samples from different shops of engineered t+G oak floor.
All of the samples we received (bar one) have the ply substrate made out of thinner strips laid next to each other, as opposed to one unique piece of plywood.
On the other hand, when I look online at pictures of similar flooring, they all appear to be made with one unique plywood piece.

Is one solution better than the other? One of the merchants involved advised that they do do it with many contiguous strips next so that the glue can bond better.

Additional question: we are going to lay the T+G floor on top of OSB T+G.
Should we use the foam underlay or not?
I read some people that say you absolute don't use it on T+G but only clip on systems, others instead say it is better if you lay it.
Most notably, I read this discussion with much interest
https://www.diynot.com/diy/threads/solid-wood-flooring-appropriate-underlay.340038/
but not really one unchallenged take-home answer!

thanks!

 

[foxhole]

The link is for solid wood floor not engineered, Use underlay .
The small strips under the floor have less effect on the top surface, if continuous strip is used and it has any curve on it this will be transferred to the top surface.

 

[TofuSpaceship]

hi @foxhole
Thanks for the reply about the underlay.
About the small strips: surely you mean the other way round, i.e. if small strips are used and subfloor has any curve, they will more likely to follow the curve as opposed to one big sheet of ply?

 

[foxhole]

hi @foxhole
Thanks for the reply about the underlay.
About the small strips: surely you mean the other way round, i.e. if small strips are used and subfloor has any curve, they will more likely to follow the curve as opposed to one big sheet of ply?

Was not referring to subfloor, but if that has a curve then should not be laid, designed for even subfloor (+or- 2mm).

 

[conny]

If it's any help to you, I once floored a large area, (conservatory, lounge and hallway), with engineered board that had small, mixed strips as the base.
I was told this was the best flooring, very hard wearing and the top surface could be sanded up to 1mm and still leave a substantial top layer.
It took about 3 weeks to lay it all, (after work in the evenings and during the day at weekends). The night after finishing I was sitting there with my granddaughter, admiring my work, when she knocked over a glass containing about 1/2 of water. I got up to get a cloth from the kitchen and by the time I came back, less than 2 minutes, the boards had lifted at the joint. They had literally instantly swelled up and split apart.
End result was I had to get an independent assessor in who said the boards were not suitable for purpose due to construction method. I got a full refund from the supplier for the original cost but nothing for my labour. Personally I wouldn't touch this type of board again.