Probably going to pick up some 4.5" wide Big Leaf Acacia solid hardwood flooring. I don't think the flooring will come with instructions since it is likely one of those from China. I could be wrong.

As far as annual weather goes, I am in East Tennessee, near Knoxville.

Instructions from another manufacturer, Bruce, state that hardwood floor planks 4" or wider should be installed using urethane construction adhesive. I assume this is to reduce the expansion and contraction that occurs with changes in humidity. I thought the exotic species instructions from Lumber Liquidators also said to glue hardwoods 4" or wider. Certainly interested in comments about using adh site on wider planks.

I would appreciate all the help I can get with evaluating my plan below.
Undercut fireplace brick so I won't need moulding around the fireplace.
Undercut drywall so I won't need anything but a baseboard along the walls.
Bring the rooms and hardwood flooring to midpoint of seasonal EMC by adjusting the humidity and temperature.
Let acclimation occur for however long it takes to get subfloor and hardwood EMC to within 2% and within normal range based on humidity and temperature.
Establish layout lines on the subfloor based on measurements.
Install starting from center of room towards outside walls to cut total expansion / contraction in half.
Installing over a conditioned / finished basement, and since I'm proposing to use adhesive, no vapor barrier.
Use a decent quality, well known urethane adhesive. Probably trowel it on so that it might serve as a partial moisture barrier.
Also use 18 gauge cleats. 18 gauge instead of 16 because Big Leaf Acacia would seem to be a denser hardwood, with Janka of around 1700.
Use a heavy roller to make sure the boards set evenly into the adhesive.

Thank you for any help,
Paul

Correction..."adh site" = adhesive. Sorry.

So have you started your install? I would offer suggestions, but I am just a homeowner as well. I am installing 5" hickory, but I have not seen anything suggesting that I use adhesive. Is this solid Acacia or engineered?

I have not started the installation yet. The Acacia is solid.

About your 5" hickory, I have asked a lot of people in the industry about using adhesive for wider (4" to 5") hardwood floors. This includes installers, retailers and adhesive manufacturers. More have said that adhesive may restrain expansion and contraction but they wouldn't use it and feel that it isn't needed. Consider that most weren't concerned about other factors as well.

I think these next questions may bring you closer to the bottom line with adhesive.
Can you get your subfloor and hardwood to the equilibrium moisture content (EMC) midpoint? If it is a well known species and your climate control can get you to the correct temperature and humidity, the EMC midpoint for the subfloor and hardwood may be reachable. For odd species (Acacia is odd), the moisture meter manufacturer may not have correction factors so the installer will likely lengthen acclimation time (at conditions for EMC midpoint) because moisture content in the hardwood can't be accurately measured. Note that Delmhorst offered to use one of my boards to make a calibration table but this would take several months.
Do you have wide swings in humidity? We do here in East Tennessee.
Can you keep moisture levels below and above your hardwood floor fairly even? In my very limited experimentation, a 10% difference in relative humidity between the basement and main level will noticeably increase subfloor moisture content.
Are you willing to do a center out install?

Feel free to respond. I may not be able to respond right away.

You will be able to use either 16 gauge cleats or 15 and a half gauge staples with your Acacia. I have used both fastening Brazilian cherry and the hardness is around 2200 as I remember.

Hi Pete,
Thank you for taking your time to respond. It is helpful to know that you've tested both of these thicker cleats and staples with Acacia and had success.

Since I made my original post, I have come to suspect that the Acacia I purchased is softer than 1700 Janka. It dents significantly easier than some White Oak that I also have. Lumber Liquidators sells a product called Hazelnut Acacia that is sold under the Virginia Mill Works brand. Janka is 783 on this LL product. I did not buy the product from LL but it seems to be closer to 783 Janka rather than 1700.

The Janka values are determined from an average over many samples.

PML, I completed my install of solid 3/4 x 5-inch hickory last week. I am in Kentucky, so my conditions will be very similar to yours. I had MC measured just prior to install, and both subfloor and flooring were within about 1.5% of each other. Relative humidity in the house has been around 52% the past few weeks. It has been a mild winter, so the heat has not been run very much, which has kept it from getting overly dry. I could tell the difference simply by the fact that I would not get shocked touching a doorknob after walking across the carpet on a cold winter morning.

I did my install from the center out. I have a stairway with ballusters going into stairnose moldings on the front of the room, and a raised brick fireplace on the back of the room. We left about 1/4 inch space by the fireplace and undercut the boards to help with expansion, and filled in with caulk. I was reluctant to undercut the brick out of concerns about chipping. I was assured by 3 different flooring professionals that going right up against the stairnose moldings for the basement stairs would not present a problem. Just to be sure, I am going to install a whole house humidifier this fall to ensure that I keep my humidity in control year-round. Hopefully we will be able to keep the floors looking as nice as they look right now.

Sounds like you thought this through pretty well, TominKY. Good job.

About the flooring that has no expansion gap at the basement stair nose - is your flooring installed perpendicular to the stair nosing? Plain sawn boards expand much less about the length of the board and much more about the width of the board (relative to one another). It may not give you any trouble. Even if it did, I would guess the stair nose could be removed and cut back from the flooring without too much hassle. Then add a bead of floor colored caulk in the newly created gap.

Large leaf acacia is a lot less harder than small leaf acacia, small leaf runs 1750 vs large leaf at 1150. So given that large leaf's density is less and moves more.