Depends on the condition of your substrate. If, it is sound, they can use a cleat nailer for the 1/2". The cleat won't damage the tongue like a stapler will.

If, you have 3/4" flooring elsewhere, I would use 3/4" solid for a nail down to avoid transition pieces. You will save more on solid flooring compared to engineered.

What is the width of the flooring?

We recommend gluing down all t&g engineered floors. Every single time there are squeaks on a nail down, it's deflection of the product on a nail that just did not get set all the way. Save yourself a lot of heartache and buy the adhesive. If you glue it down, there really is no performance difference between the flooring thicknesses.

G&S,

A cleat actually cuts the hole in the tongue as it punches through. A staple wedges the product away and to the sides.

We've had claims over the years with installers using staples on a smooth engineered floor while jacking the PSI way up. The high PSI sets the staple too deep. The bridge of the staple carries wood with it and acts like a wedge which causes the floor to pucker. On several jobs I inspected you could see a pucker every single place the the floor was stapled. I've never seen a cleat nailer do this.

G&S,

Width of the flooring is 5".

A full glue down is your best installation for 1/2"x5" engineered flooring. A nail assist is second with a nailing schedule of 24" to prevent crowning issues like WeShipFloors mentioned.

WeShip, I did recommend using cleats and not stalples.

If I were to use 3/4" version of the same engineered hardwood, would you still recommend that get glued down as well? Am I right in being hesitant to glue (vs nail) the floor down (just in case a board gets damaged and needs to get replaced)? On the main floor we have a total of 1 1/8 subfloor while upstairs we have 5/8. Yes, I agree, transition will be better at bathrooms with 3/4 especially upstairs as we have a 1 1/8th subfloor in bathrooms with tile installed on top.

Obviously there is a price difference between the 1/2 and 3/4 and I have already put a deposit down on the 1/2" eng, but I'm now second guessing if I should have ordered the 3/4 version to prevent squeaks. I'm also thinking that folks install 1/2" engineered floor all the time?

For 3/4" x 5" , You will need to do a nail assist installation, which is a full troweled glue as your main fastener and cleats or staples, spaced 18-24" as secondary fasteners. This is standard installation practice for wide planks.

The alternative is to do a glue assist, which is the opposite of a nail assist and much more tedious. Beads of glue is applied in a continuous "s" pattern on the back of "each" flooring board and nails/staples are at 6"-8".

The nail assist is a better and faster install, but not the cheapest. With the correct type of adhesive, the adhesive acts as a vapor "retarder" , not trapping moisture on or above grade installation. More prep work is involved.

If, the installer does not have familiarity with adhesive types. Have them use the glue assist method to stay on the safe side. Or find someone who is.