Hi all,

I am in a bit of a dilemma. I had ordered 0.75 inch thick/5 inch wide engineered flooring, but the manufacturer only has 0.5 inch thick wood available.

My stair nosing is 0.75 inch thick. Other than the increased cost, are there any downsides to using the 0.5 inch wood and building up the subfloor with a 0.25 inch sheet of plywood?

I understand this will cost more to do, but I am more concerned with the durability/integrity of the 0.5 inch wood vs. the 0.75 inch wood. Some installers have told me that 0.75 inch thick wood is better, but no solid justification has ever been provided.

The range of humidity is slightly less for the 0.5 inch wood but still okay at 38-50% and the wear layer is the same on both products at 4mm.

Should I wait for the 0.75 inch wood to become available or just install the 0.5 inch wood with the 0.25 inch plywood underlay?

Best,
Neil

If your plan is to glue the flooring you can expect either thickness to perform well. Glue down is recommended for five inch and wider engineered flooring. Glue and fasteners could be better as the fasteners would hold the flooring until the glue hardens.
I would rip the nosing to half inch thickness and use the half inch thick engineered flooring. A quarter inch difference in the height of all the treads at the start and landing steps will still be up to code for safety.
Adding a layer of quarter inch plywood makes another layer that will not add to structural integrity. It's just another thing that can go wrong. If the sub-floor is not flat the quarter inch could cover shimming to help even out the surface, but that would be the only advantage I would consider.
A good sub-floor will provide the strength for the half inch thick flooring to be fastened.