Hi,
I got some 3/4" x 5 1/4" prefinished Austrialian cypress from you-know-where, and after testing some pieces with a pneumatic flooring nailer using 16-gauge L-cleats, I have found that tongue splitting is a major problem. I have tried adding tape to increase the angle of the nail, I put on the 1/2" flooring pad that came with the nailer, reducing the air pressure as low as 40 psi, but it keeps splitting. Even hand-nailing one of the cleats still caused splitting, so I think the wood is just to brittle to accept the 16 gauge cleat.

We have about 300 sqft to install. I can shoot 16 gauge finish nails through it just fine.

I was planning on putting paper under the flooring, and nailing. What if instead I used some PL400 under the boards, and blind nailed it in with 16 gauge finish nails?

I have heard that maybe an 18 gauge or 20 gauge flooring cleat might reduce splitting, but it seems like those nail guns are somewhat exotic-they don't sell them at local stores, or rent them at the rental shops.

Should I just bite the bullet and drill and hand nail the flooring? (if so what kind of nail would be recommended?)

The substrate is 3/4" plywood, on top of a layer of 3/4" Advantech.

Thanks for any suggestions,
Nat

PS: Should I try staples? They look thinner, but people say the wide striker can lead to tongue splitting. That said I have a nailer/stapler, so I guess it's the same striker in my case.

aussie cypress is horribly brittle. You really do need a 18gauge nailer. Powernail model 50p is what you are looking for. If you go to the powernail site they have a dealer/rental locater that may help you find one.

Kevin,
Thanks a lot! Couldn't find any other way to locate the 18 gauge nailer. Looks like it might be a 2 hour drive, but those things are really expensive to buy. I went with the $120 harbor freight nailer/stapler initially.

So I talked to lumber liquidators, and they basically said 'don't worry' about a little splitting near the ends of boards. Maybe thats OK, but I would be worried about board moving and lifting up over time if you split out the tongue. They also said staples are recommended, which I know is a much debated topic...maybe I will test the staples and see how that goes.

Is the glue down method (PL400, no moisture barrier) something to be avoided then?

are you using 16g pneumatic. I find that pneumatic splits more than manual. If your using pneumatic try manual. Its worked for me on a lot of exotics.

Lumber Liguidators Flooring 101 states 18 guage cleats. Charles Peterson book a complete guide to Layout, Installation & Finishing states that using a 1/2" staple is like using a wood chisels on the tongues. I inspected 2,000 sf of LL Australian Cypress 4 3/4" wide tongues split extensively. Additionally Mohawk, most manufacturers and Charles Peterson now recommend that a Serpentine bead of construction adhesive 3/8" wide be used on the side away from the tongue, and on the ends, to insure enough force to hold down the plank. Even nailing 6" to 8" only provides 400 lb of force whereas 2 1/4" nailed 8" to 10" inches provides 700 lbs of force. Utilizing the construction adhesive provides over 700 lbs of force. Pay particular attention that the moisture content between the subfloor and hardwood is no more than 2% before proceeding.

So what I'm really wondering, is how much does tongue splitting affect the strength of the floor? Wouldn't the wood tend to pop up as it expands, if the tongues are split? Probably it will only split near the ends, so maybe I'll use finish nails near the ends of boards.

Would anyone recommend applying Bostik MVP as a moisture barrier, then gluing and nailing the floor boards down? Seems like more work and materials cost. The floor is over a basement, but there is 3/4" plywood, then 3/4" Advantec, then 7" of netted densepack cellulose between the floor and basement. Not sure if moisture would be a problem, but I was going to use felt paper.

Tonge splitting = squeaks.

The adhesive will just make plank replacement a nightmare.

Just tried staples, and that seemed to do the trick! Thank for the advice.

If I can try one more question...last thing I'm worried about. One floor has 3/4" plywood over 3/4" Advantec. 2" staples will go through the hardwood, plywood, and penetrate a little into the Advantec, which is a much harder then plywood. Could that cause a stapling problem? Would movement between the plywood and Advantec push the staples up over time? The layers are glued+screwed. The reason for the second layer is that it is an old house with 26-29" joist spacing.
Thanks,
Nat

dont see that being an issuse. we have alot of advantec used in this area and its not a problem.