Nailing Down a Floating Floor?

Question

I am installing laminate tongue-and-groove floating floors in my kitchen with the aid of my Grandfather. I was always under the impression that a floating floor was just that - not pinned down by glue, nails, etc. in order to let it expand with humidity (which I live in northwestern PA, so fairly humid in the summer). However, my Grandfather insists that it HAS to be nailed down. He has barely gone into any reason why. He was a carpenter his whole life though, so I decided to do more research, and found that mostly people do not nail them down, but there might be advantages to it.

Related questions like Should I install a floating floor or a staple down for engineered hardwood? are helpful, but there are also resources like USING THE POWERNAIL 2000 TO INSTALL A FLOATING HARDWOOD FLOOR say that there are advantages and you SHOULD do it (but they could also just be trying to sell me the nail gun).

Is my Grandfather correct and the floor should be nailed, or should I push back more?

Answer 1

From the link you provided:

Another issue with floating floors is that once they are installed, they tend to behave like one giant entity. What this means is that the floor will require a gap (generally 1/4″) around the entire perimeter of the room. The whole floor will shift this amount depending on the fluctuations in humidity or moisture in the environment. When you nail down the boards they will still expand and contract. However, they will not move as much.

"However they will not move as much" ? Each board will expand or contract depending on temperature and humidity, and much more than hardwood will. Hardwood attached to a subfloor can expand and contract with each other. The floating flooring expands and contracts much more.

The amount of movement of any plank does not just depend on its contraction or expansion but also on the contraction or expansion of all planks surrounding it. If you pin them all down, they all move a bit with tremendous pressure on the sub-floor. This usually causes the flooring to bulge or the seams to open.

The advertised benefit of nailing is that the flooring can follow the dips and bulges of the subfloor. But the solution is not nailing, it's that you should level (flatten) the sub-floor first. So if it's flat, there's no need to nail, and you'll have no seam gap and bulging planks.

The manufacturer of your flooring can tell you whether it can be nailed. If so, then you don't need a 1/4in perimeter or a T-transition, since the planks don't contract or expand much anyway. And then there will be more tolerance for sub-floor imperfections if you nail, and less tolerance if you float.