Is it true that gluing the ends of 5" and wider solid hardwood flooring is necessary for proper installation?

Glueing the ends?
As in glueing the tounge and groove on the butt ends to eachother?
Or as in glueing the ends of the flooring to the subfloor?

Nothing is actually "nessicary" But anything 4 inches or wider I prefer to glue to the subfloor. Im sure NWFA recomends gluing 5+ inches, But glueing and stapling 4"+ Makes me and my customers sleep better (because there is no squeking/poping/crackling)

Don't glue the T&G butt joints together when using a solid.

I installed a mohawk or Bruce solid product three years ago or so that was a 3 1/2" solid product that required gluing of the butt ends of all boards.

I have since begun gluing the butt ends of all 4" and wider material. Since the wider material will react more to moisture, I figure this will help in avoiding the gaps and checking in the floor after it has been laid.

Sorry, I stand corrected. I have not run into that before on any solid floor I have installed.

Are you sure it meant to glue the T&G, or to actually use glue on the bottom of the planks at each end??

Like I said it was quite a while ago, and don't have the directions readily available. But I am a guy who sticks very closely to the manufacturers procedures. Customers pay for the warrantees and I as the installer wish to see them honored. I read their recommendation very closely. My understanding as I can recall was to apply a wood adhesive to the upper side of the female portion of the butt ends of the flooring planks.

Remember this was only a 3 1/2" wide strip floor! Seemed a bit odd to me at the time, but when the manufacturer asks you to follow a certain procedure. Damn straight, I am going to. Then if there is a problem, my experience is that they will come to the table and make sure the problem is resolved. Believe me that is a welcomed response.

Since this install I have incorporated this procedure in all my floors 4" to 5" (not having installed any larger the a 5" width"). Just to help mitigate the checking and seasonal gapping that might occur.