Solid Hardwood, Engineered and Laminate Flooring - Expansion gap question

:wall:

Hi:

Just finished (Saturday) laying down a new engineered hardwood floor (white oak, 3/8" thick) on the first floor of my home. Stapled it down. I did have to glue down a row at the end as I could not face-nail under the hydronic baseboard heater.

I followed the manufacturer's instructions regarding the expansion gap at the edges, which is 3/8".

I understand the concept of expansion and contraction and leaving room. What I don't quite understand is how the floor will expand and contract and remained stapled down. Is the floor independent of the subfloor? Or is it assumed the subfloor will move at the same rate?

Perhaps one of the experts here will be able to explain it.

Thanks.

:coffee:

Flooring will most of time buckle out in the field, before it takes up the expansion space. If your flooring stays at a constant moisture content like it should be, no expansion space would be needed. A floor that swells enough to take up the required expansion space will render the fasteners useless.