Brazilian Cherry 3/4 x 5 plank - Nail or Glue AND Nail?

[M3Pilot]

I haven't found much info on this question and what I have found isn't consistent so I'd greatly appreciate any thoughts on my specific install.

I have ~1200ft of 5" bc plank to install on my first floor. Particulars are:

• Full basement under entire install area.
• Subfloor is 3/4" plywood in new construction area and 1/2" plywood over existing (1939-era) hardwood.
• Moisture testing currently showing a 0 - 2% difference in moisture content between floor material and subfloor after a week of acclimation.
• Located in the midwest with large variations in climate. House is pretty tightly climate controlled and now has all new windows, doors, HVAC, etc.
• BC flooring is Bellawood from LL.

As the title says I'm not sure if I should nail only or glue and nail and the more people I ask the more confused I get. The salesman at the LL where I purchased the material recommended a trowel-on urethane adhesive and nailing which is what I had planned to do. But then I started to see some comments on the net and elsewhere from folks who didn't think it was such a good idea - either because it was simply unnecessary or that it could introduce other problems (trapping moisture?). Then I happened into a different LL last weekend and their installer told me to glue and nail but don't use the trowel-on stuff. Instead he suggested running a bead of "Liquid Nails" (he didn't specify which flavor but none I know of seems appropriate for hardwood flooring). I've found passing references to using other adhesives like Weldbond as well.

I have to say that I'm not thrilled with the idea of having to trowel the urethane stuff on plus the cost to do 1200ft isn't trivial but it's more important to me that I do it right. So what is the right way for this scenario???

While I'm here - I bought a Bostich stapler on the recommendation of my contractor based on his flooring sub's suggestion. It seems though that the general concensus here is that for harder exotics cleats are a better choice. I haven't used the tool yet so returning/exchanging is no problem. Is that the way to go? Any contrary opinions?

Thank you to all for any insights,
Stuart

[Peter Kodner]

Stuart a slew of questions for you but first, unless LL and the installers you have gotten advice from have written a new standard, and are willing to warranty the method if you have a problems, I certainly would not use any adhesives.

Gluing and nailing would to my mind create expansion and contraction issues. 3/4" solids in your five inch width are not recommended Further, although Jatoba (Brazilian Cherry) has a shrink/swell coefficient about 1% less than red oak, my experience, borne out by others comments here, are that it moves considerably more.

Jatoba is very much on the difficult side for installation. As it is very hard, cleats will be easier (and IMHO, better long term) but you may find you will need to drill holes to prevent splitting. You will not know this until your start installing.

How was the moisture content checked? Jatoba can take months to acclimate, although if it has been sitting in a climate controlled area (LL's warehouse, if it is under HVAC)for considerable time, it may be good to go.

What do you intend to place between the flooring and subfloor for a moisture retarder?

Do you know the nailing schedule for this floor?

Are you prepared to observe the expansion space needed?

What is the joist construction and direction to the plank flooring?

Have you checked for subfloor flatness?

How many areas is the flooring going into? Sizes of them? A diagram would be helpful.

I do commend your asking advice here. You are putting in a floor that should never need replacement, predicated on doing it right the first time...

[M3Pilot]

Peter,

First and foremost, thank you very much for taking the time to thoroughly analyze and respond to my questions! It's extremely important to me that I do this the right way and I really appreciate the input.

Peter Kodner said How was the moisture content checked? Jatoba can take months to acclimate, although if it has been sitting in a climate controlled area (LL's warehouse, if it is under HVAC)for considerable time, it may be good to go.

I purchased a Lignomat Mini Ligno E/C (pin style) meter from a local woodworking supply shop. I had been looking at devices a bit more sophisticated but this one was available locally so I figured I'd give it a try. I'm getting consistent readings of 5% (6% on the meter -1% adjustment for species). It's only been acclimating in my HVAC-controlled house for a little over a week and before that it spent a couple of months stacked in my garage. Given that should I consider the readings suspect? I've tried multiple technics and always get similar readings. Subfloor is registering 6%. I've tested known damp lumber as well and gotten much higher readings so I'm confident the meter doesn't just show 6% on everything.

Peter Kodner said What do you intend to place between the flooring and subfloor for a moisture retarder?

This has been dependent on the answer to my glue and nail/nail only question. What do you suggest if I nail only

Peter Kodner said Do you know the nailing schedule for this floor?

I do not but it is on my list of things to determine before I begin. Up until a couple of days ago I had planned to staple and had purchased a Bostitch stapler. Based on comments here and elsewhere I've decided on cleats so the Bostitch is going back and I've got a Primatech 240 on the way.

Peter Kodner said Are you prepared to observe the expansion space needed??

Are refering to spaces left within the floor field and not just along the perimiter? Actually I wasn't sure on that one as I recall seeing some differences of opinion on that too. Recommendations?

Peter Kodner said What is the joist construction and direction to the plank flooring?

I plan to run all floor perpendicular to the joists (unlike some of the original flooring interestingly enough). Existing house uses 2x10 lumber on 16" centers. New addition uses 2x10 engineered I-joists (OSB verticle "spine" with 2x3 wood top and bottom) on 12" centers. The contractor put 3/4 OSB over the new joists to which I added 3/4" TnG plywood for both added height and what I thought to be better nail holding.

Peter Kodner said Have you checked for subfloor flatness?

I'm focusing on the new addition first and yes, subfloor is flat. My kitchen/office area is next and since they used to be two separate rooms with different floors they are very slightly off from one another. My plan was to use different weights of asphalt felt paper under new 1/2" plywood subfloor to equalize (the difference is very slight).

Peter Kodner said How many areas is the flooring going into? Sizes of them? A diagram would be helpful.

Basically 3 areas but I am still debating if I want to run the floor continuously from the kitchen/office space into the living room area. I haven't decided if it's worth the effort/challenge or not. The new addition (study? not sure what to call it) has joists running the opposite direction and more clearly seperated from the adjoining spaces. It's basically a 16'x20' rectangle so I'm starting there to get some experience. I can knock up a diagram fairly easily and post it later.

Peter Kodner said Gluing and nailing would to my mind create expansion and contraction issues. 3/4" solids in your five inch width are not recommended.

Their rationale seems to be to prevent cupping but I must admit that the suggest left me a bit uneasy for the reasons you state. If natural expansion/contraction caused the glued surface to seperate I fear that the results could look worse. I also has wondered about the glue actually trapping moisture but maybe that's the point. Clearly I'm NO expert!

Peter Kodner said Jatoba is very much on the difficult side for installation. As it is very hard, cleats will be easier (and IMHO, better long term) but you may find you will need to drill holes to prevent splitting. You will not know this until your start installing.

If I have to drill I assume that means hand nailing, correct? If/when I do split a tongue do I remove and discard the board or can I still drill/nail it? Is there any advantage to T-cleats versus L-cleats?

Thank you again for taking the time to help!

Stuart

[Peter Kodner]

You are welcome. I'm sure others will add to the thread shortly. A great group here even if we don't always agree on everything

The Mini, if I'm recalling correctly, uses LEDs as opposed to a gauge or digital read out. I think you should be okay but can the calibration be checked? Bear in mind the accuracy on meters is less when you are near the end limits, in this case 6% and lower. Temperature and relative humidify should be taken, at the floor level, so we can determine if you are at equilibrium with your environment. For 5% MC, at 70 degrees F, your Rh would be about 22.5%! That seems awfully low for the Midwest in the summer, even with AC running. A wordy way of saying I'm not comfortable with your readings... You are correct in wanting the subfloor and flooring within 2% of each other. You fall into 2 areas where 2% is needed: an exotic and a plank.

I'm a fan of Aquabar, which is an asphalt sandwiched with Kraft paper. A good perm rating for your use and the asphalt they use will seal around your fastener perforations.

The NOFMA installation standards used to be available on the net, but as NOFMA is now a part of NWFA. NWFA does not post this info free on the net. Plank floors (anything over 3 1/4 inch wide) calls for Fasteners 1-3" at the ends and every 6-8" along the planks. Face nailing should be every 10-12". With the subfloors you describe, 2" fasteners should be best.

I was referring to the rooms perimeters. You will need a full 3/4 inch so wood base and base/shoe or quarter round is usual.

Construction sounds fine but an unsupported span dimension would be helpful to verify deflection will not be problematic. By all means, install perpendicular to your joist directions.

You want to have the subfloor flat to 1/8" in 6' or 3/16" in 10'. A 10' section of pipe is great for verifying this. I use taper gauges but most folks don't have them (they are a bit pricey if you don't use them regularly). A small steel ruler will work fine for measuring flatness variations. The rulers are less than $3 at any hardware store.

If your largest room is 16 X 20, you should not need to start in the center and install in 2 directions. This makes it easier for you.

If you split more than a quarter of a tongue off, I would pull the piece and use it for fills. To be completely comfortable, you may want to cull them for even less damage. A bit of a catch 22: you won't know you have a tough plank until you fasten it and then it is too late to drill and hand nail... You will want to look at each piece as you rack it and cull any the have insect holes, knots or any other visible imperfection at the plank edge or in the tongue. Bear in mind Jatoba has frequent cross grain which may not be readily visible. Makes it a bear on occasion.

You couldn't have chosen a nice simple 2 1/4 oak strip for your first big one?