Engineered Oak - Crowned out of the box.

Hi all
I'm based in UK - so our climate tends to be a bit more humid than some..
So I've recently taken delivery of a load of new Engineered Oak.
I've already unpacked a few boxes and most of it is crowned..
There is also some bowing - but I'm not so concerned about this as it will be lost once the floor is laid.
I'm not sure if this has happened subsequently to unpacking - it's been out of the box for a couple of days.
In terms of acclimatisation, it has been kept in the installation location. The room has new hardwood double glazed windows, Solid wall insulation and a chipboard subfloor with uncommissioned underfloor heating pipes. There is a layer of ply screwed to this. So I'm just trying to make the point that there is no inherent damp issue.
The acclimatisation advice was to store in the destination room in anticipated environment. So there is currently no heating in the room as it's summer and a bit of a warm spell, however the relative humidity is 60% - 65%. This is actually the same as outside at the moment.

So I'm not sure if there are acceptable tolerances or if the boards should be bang on flat.
It's a bit annoying as I'll have to increase the adhesive bed depth to achieve a full bond.

The boards are 240mm (9.5") wide.
If lay a straight edge across the width of bottom of the board there is generally around 1mm -1.5mm gap in the middle (so the bottom is concave)

So my questions are:
1. Would this be considered normal and acceptable tolerance?
2. Should I reduce the relative humidity in the rooms in the hope that the boards will flatten - prior to installation - my instinct is that this wouldn't help particularly as the RH will normalise after laying in any case...

Any advice would be great
Many thanks
Sky

 

Where did you get the engineered wood from?

 

luxuryflooringandfurnishings

 

Would take alot to crown engineered oak. I wouldnt be surprised if that was a manufacturing issue. Could have been poorly stored at some point. That’s a very wide board so maybe the veneer is stronger than the plywood base? We never take the planks out of the box until installation as they can move and bow depending on how they are made.

 

Thanks for your comments - Yeah we only had it out of the boxes a few days so we could cut and number the pieces..
I was quite surprised too at the extent of the crowning - I know oak can exert some quite powerful forces, but there is only a 6mm wear layer.. I'm not going to open any more of the boxes until fixing now and we'll just cut as we go along.. I've sent pics to the supplier for now.. See attached

 

Thats no good. I would send it back. 6mm veneer is pretty thick

 

I always tell my customers to leave them in the box till I turn up to fit. Had it before where half the batch was crowned and the supplier replaced the lot but one of the pictures the customer sent to them had a fresh plastered wall in the background and at first they were saying it could be down to the moisture coming out but she sent them the pics of the other lot they stored in another room that hadn't been touched so they said they'll pick up and replace the lot.

 

Them pics you've put up look quite bad, alot worse than I've seen before, definately need replacing.

 

Perhaps as you say leaving them unpacked until laying may have helped. But would you agree - on the basis that one of their installation recommendations is to install as a floating floor, even if I had left them boxed until the last minute, I would still have faced the same problem? Obviously with an adhesive install it is likely to be a different scenario. As a test I have put a small piece of the flooring in a closet with a dehumidifier for a number of days and have been checking with a straight edge and Vernier gauge and there are no signs of normalisation yet...

 

Thanks for your input, Yeah I can understand and agree with that strategy, but this is a normal environment. and as I said above, they recommend floating floor as a possible option. So had I laid it as a floating floor I would have faced the same problem as far as I can see.. The room is currently unheated, but it is far too warm to have heating on in any case and the RH is similar to external RH..

 

That

leaving them in the pack just helps to stop them bowing. Once its all locked together it starts to settle down and holds itself flat.
What you have is a damaged board. Only time ive seen engineered warp like that is when its been stored badly. Did you take a moisture reading of the boards? I mean they could have dried out now anyway but always worth checking. Is there any manufacturing dates on the wood? Could be old stock. Either way it looks damaged to be and i cant see you getting that flat with that size board.

 

Is your project a building site? Did you take delivery after all wet trades?

 

Just to add 65% Rh is too high for room humidity it needs to be between 35-55%


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It sounds like you've done a thorough job preparing for your installation. Here's some advice:

1. Normal Tolerances: Engineered wood flooring can have some natural variations. A 1-1.5mm gap with a straight edge over 240mm wide boards is generally within acceptable tolerances for engineered oak flooring. However, excessive crowning may still warrant a discussion with your supplier to ensure this is within their quality standards.
   
   
2. Relative Humidity: Reducing the relative humidity in the room might help the boards flatten out slightly, but as you've correctly pointed out, the RH will eventually normalize to the room's natural conditions. It's more important to ensure that the subfloor and the environment are stable and within the recommended humidity range for the flooring.

Additionally, since you mentioned needing to increase the adhesive bed depth, make sure you're using a flexible flooring adhesive designed for engineered wood to accommodate minor variations in the boards. If you're still concerned, consider consulting a professional installer for their opinion on the condition of the boards before proceeding.