I am going to be installing around 2000 sf of 5 1/4" wide cherry T&G solid flooring. I am concerned that blind nailing the floor will not be sufficient for fastening the floor to a 3/4" plywood subfloor. I'll be using bostitch 15.5 gage staples and an air nailer.

Is my concern warranted? Would 6-8" staple spacing be sufficient? Would it be better to for go the felt paper and lay the floor in a bed of construction adhesive and staple at 8" intervals as well? If an adhesive is used, what products are suitable for this task?

The installation is above grade, over a heated basement.

Thanks in advance.

For fastend down wide plank I would use Liquid Nails with a bead down each side of the boards length, and also a blind nail on the ends out to the edges(glue tip finish nailer), being real careful not to split ot bust off the tongue.

Gluing and nailing will do a better job but as you probably know, it will take a bit longer. Some guys like to use Bostick's Best and full trowel it on. When I've down wide planks, I've used PL400 in a tube. It's probably slower but definitely neater. BTW, you didn't say which cherrywood you will be installing? Nowadays, there is all kinds of floors called cherry. There is TRUE North American Black Cherry, a beautiful but soft wood; Brazilian Cherry, also known as jatoba, hard and some say not stable ( I've had no problems ), Bolivian Cherry, Chilian Cherry, Peruvian Cherry, etc. Pretty soon, we'll have Puerto Rican Cherry, Honduran Cherry, Argentinian Cherry, Panamanian Cherry, Venezulian Cherry, etc. You get the picture. Anyway, what's yours?

The floor is true NA Cherry, not an import, from a New York state mill. I'm aware it is a little on the soft side, but it's truly beautiful, and if I recall correctly, a fairly stable species in wide widths. While the softness is of concern, few dings are not detract from the look as I have built a timberframe house, so it's more like a highly polished rustic look rather than formal. I needed a wider floor board to complement the bulk size of the timbers. A narrow strip just doesn't look at home next to the 10x10 timber columns.

This is a project for my house, so time is not a factor, longevity and a proper installation is my primary concern.

Floorguy: what nail spacing are you using? If I understand your post correctly, you are using very few nails relying mostly on the glue correct?

Gary: Are you using full coverage with the PL400 or just two beads lengthwise on the bottom of the plank? Is there any concern forgoing the vapor barrier? Also is 8" staple spacing sufficient?

As a side note, I'll be using 4 1/4" Black Walnut in our bedroom. Again a softer but more stable species than oak. Would 8" staple spacing w/out gluing be sufficient?

6" spacing for the fasteners on wide plank.

Thanks, If I understand you correctly, you are using two beads of glue on the bottom of the flooring, correct?

I do, because cupping is at the edges of the length and the wider the plank, the more they tend to cup. Some pro's do a zig-zag all the way down the board.

While gluing and nailing will help reduce some movement the only real way to insure a floor will stay flat is by controling the temp and rh consistantly year round. On wide plank be sure your floor and subfloor are within 2% of each other.

On nailing. Nailing to close together can cause tongue split. The staples used in the Bostitch M111FS can cause more tongue split than cleats. I recommend nailing no closer than the NWFA and NOFMA recommendation of every 8" and within 2" of the end butts. PL400 is not used to full spread. It's in a tube and it's a construction adhesive. It was recommended to me by Carlisle Restoration who is the manufacturer of wide plank historic floors. Their system is to blind nail 8"oc with the Bostitch M111FS and place a 1/4" bead of PL400 8" oc on the back of the boards running from the tongue to the groove. I found that staying away from the edge by about 3/4" was a good idea. Also, if your on the second floor above a heated space, there's no need for the asphalt felt. The glue will be more of an improvement than the felt. The glue and nails will not prevent the flooring from normal expansion and contraction, as Keven pointed out. That is controlled by maintaining temp and RH.

Thanks for the replies and guidance. I'll report back in a month or so after the install.