Located in upstate NY (5 hrs NW of the big apple) First floor area of a 1930 era house, hot water radiant heat (wall radiators) no A/C in summer, no direct humidifier in winter, moist basement. 10’ x 15’ dining room, floor joists 24” oc, with 2 ½” t&g sub floor, 11 x 21 living room floor joists 12” oc with same 2 ½” t&g subfloor. I will be removing the existing 5/16 x 1 strip floor due to damage and relocation of walls. New floor will be ¾” x 3” solid white oak rift and qtr sawn sourced directly from NYS flooring mill, finished on site (by professionals).
Questions
1. I would like to change the direction the flooring should be installed. Can I install a layer of plywood over the existing subfloor, then install the new flooring parallel to the 2 ½” t&g subfloor? What is the minimum thickness of plywood I can use?
2. Should I install a vapor barrier and felt or rosin on top of the vapor barrier?
3. I have always used cleats but based on the informative nails or staples thread I will rent a stapler and use 15 ga. known name brand staples. What is the recommended staple spacing from ends and down the length?
4. Acclimate schedule. This portion of the house will slowly dry out all winter long we do have conditioned air (furnace) in another part of the house that communicates with this area a little. I have the time to spare, how long should I allow the flooring to acclimate?
5. When using a spline to change directions, is the spline glued in, then staple down flooring so that the splined piece will end up stapled along both lengths?

I would say the following post would throw up a red flag if I was installing this 3/4" hardwood floor.

1: no A/C in summer(between 65 – 75 degrees and a relative humidity of 35%- 55% prior to delivery, during, and after installation of the flooring)
2: no direct humidifier in winter (between 65 – 75 degrees and a relative humidity of 35%- 55% prior to delivery, during, and after installation of the flooring)
3: moist basement (Basements and crawl spaces must be dry)
4: 10’ x 15’ dining room, floor joists 24” oc, with 2 ½” t&g sub floor (On truss/joist spacing of 16” o/c or less the industry standard for single panel sub flooring is nominal 5/8” 19/32”, 15.1 mm) CD Exposure 1 sub floor panels, 4x8 sheets.)
5: 11 x 21 living room floor joists 12” oc with same 2 ½” t&g sub floor.(On truss/joist spacing of 16” o/c or less the industry standard for single panel sub flooring is nominal 5/8” 19/32”, 15.1 mm) CD Exposure 1 sub floor panels, 4x8 sheets.)

Acclimate schedule. This portion of the house will slowly dry out all winter long we do have conditioned air (furnace) in another part of the house that communicates with this area a little. I have the time to spare, how long should I allow the flooring to acclimate?

No set time, material is acclimated once it has reached moisture equilibrium consistent with the temperature and relative humidity of the job site and normal living conditions.

Test wood sub floors and wood flooring for moisture content using a pin-type moisture meter. Take readings of the sub floor – minimum of 20 readings per 1000 sq. ft. and average the results. In most regions, a “dry” sub floor that is ready to work on has a moisture content of 12% or less. For solid strip flooring (less than 3” wide) there should be no more than a 4% difference between the wood and sub floor. For plank flooring (3” or wider) there should be no more than a difference of 2% between properly acclimated wood and sub floor. Failure to test for proper moisture content of the wood flooring and sub floor
can result in cupping and/or other problems related to or associated with moisture and are not covered under most manufacturer’s warranty.

I would like to change the direction the flooring should be installed. Can I install a layer of plywood over the existing sub floor, then install the new flooring parallel to the 2 ½” t&g sub floor? What is the minimum thickness of plywood I can use?

First I would correct the 2 1/2" t&g plank sub floor.

Determine the direction of the floor joists – Run the flooring perpendicular (90°) to the floor joists. Do not run plank flooring parallel to floor joists unless a minimum nominal ½”(15/32) CD Exposure 1 (CDX) plywood underlayment is added.

Should I install a vapor barrier and felt or rosin on top of the vapor barrier?

Prior to installing flooring roll out 15 lb. asphalt saturated felt paper – overlap joints 6” and staple if needed. However, by today’s standards, asphalt saturated Kraft or felt paper may not be an effective vapor retarder in all applications. The 2006 International Residential Code requires a vapor retarder on the warm-in-winter side of exterior floors (a floor over a vented crawl space, for example), with a vapor permeance of 1 perm or less in Zones 5 and higher. This material will help to keep the floor clean and help to retard moisture from below (there is no complete moisture barrier system for staple or nail-down applications).

On truss/joist spacing of more than 16”, up to 19.2” (488mm) o/c, the standard is nominal ¾” (23/32”, 18.3 mm) T&G CD Exposure 1 Plywood sub floor panels, (Exposure 1) or nominal ¾” 23/32”, (18.3mm) OSB Exposure 1 sub floor panels, 4’x8’ sheets, glued and mechanically fastened.

Truss/joist systems spaced over more than 19.2” (488mm) o/c up to a maximum of 24” (610mm) require nominal 7/8” T&G CD Exposure 1 Plywood subfloor panels, (Exposure 1), or nominal 1” OSB Exposure 1 sub floor panels, 4’x8’ sheets glued and mechanically fastened – or two layers of sub flooring or brace between the truss/joist in accordance with the truss/joist manufacturer’s recommendations and with local building codes. Some truss/joist systems cannot be cross-braced and still maintain stability.

Permanent HVAC should be on and operational a minimum of 7 days and maintained between 65 – 75 degrees and a relative humidity of 35%- 55% prior to delivery, during, and after installation of the flooring.

I have always used cleats but based on the informative nails or staples thread I will rent a stapler and use 15 ga. known name brand staples. What is the recommended staple spacing from ends and down the length?

Minor occasional noises within the flooring are inherent to all staple/ nail-down installations and can change as environmental changes occur. This is not a manufacturing defect and is therefore not covered under warranties. You can help reduce squeaking, popping, and crackling by being sure that the sub floor is structurally sound, does not have any loose decking or joists, and is swept clean prior to installation. You should also be sure that your stapler or nailer is setting the fastener properly, not damaging the planks, and that you are using the correct nailing schedule.
When used improperly, staples or cleats can damage wood flooring. If the tool is not adjusted properly the staples/ cleats may not be positioned at the proper angle. Test the tool on a piece of scrap material first - set the stapler/ nailer flush on the tongue side of the plank and install a staple/ cleat. Should the staple/ cleat penetrate too deeply reduce the air pressure; if the staple/ cleat is not deep enough then increase the air pressure using an in-line regulator. The crown of the staple/ cleat should sit flush within the nail pocket to prevent damage to the flooring and to reduce squeaking. The flooring manufacturer is not responsible for damage caused by the mechanical fasteners.

3/4" hardwood needs fasteners 1"-2" from ends/spaced 8"-10" apart.

Stanley Bostitch(multiple models) with M-4 foot 15 ½ Gauge Staples
Pneumatic Powernail 445 1-1/2" - 2" 16 Gauge Cleats
Pneumatic Powernail 50P 1-1/2" 18 Gauge Cleats


The above post are copy and paste from a hardwood installation pdf. You probably should get the installation guide from the wood floor manufacture, as they could and likely do have different installation producers to follow. I can link to this entire installation pdf if You need.

I would go over the existing flooring. Check for flatness and grind high areas and build up low areas with layers of thick tar paper, roll roofing will raise the height approx. one eighth inch per layer. Quarter-inch plywood where walls are being removed. Rosin paper will make it more pleasant to work over with less dust to kick up when the floor is dropped into position.
Staples, 2 inch long,placed within 3 inches of the ends and 10 inch spacing will be good. You may put a staple into the tongue at the end of planks.
You can use a moisture meter to check the existing flooring, then compare to the new flooring. If there is not a match, you will be able to use a table to compare the moisture content of the new flooring with how much expansion (width of each board on average) will occur when it does match with the moisture content of the acclimated flooring as a yearly average depending on the moisture content projected for your area, which should come close to the moisture content of your old floor, now.
Will a spline that fits your flooring, there will not be necessary to use glue to hold the spline in place. Just nail right through it after it is slipped into place. If you have trouble with it popping away from the staple then you will need to glue it then staple after the glue has dried.
It is recommended to cover any dirt in the crawl space with 6 mill plastic sheeting to keep moisture from evaporating into the crawl space, overlap at least a foot or tape the edge joints.

I appreciate both replies. I did pull the NWFA guidelines (I should have started there)

"First I would correct the 2 1/2" t&g plank sub floor."

As much as I would like and prefer, it is not practical to remove the existing 2 1/2" t&g sub floor. There are remaining walls that are built on top of it and do not line up with joists below. There are to many obstructions below to try and add blocking/sleepers joists. I am concerned with poor fastening when the nailing of the new floor lines up on sub floor seams.

Re. "I would go over the existing flooring." I assume this does not include ripping up the strip or adding a layer of plywood. Besides filling in where walls have been removed there isn't any leveling required. The existing strip floor was installed perpendicular to the sub floor which was installed perpendicular to the joists. Which direction relative to the existing strip floor do I install the new plank flooring?

I should clarify, the basement below this area of the house is not a crawlspace or a dirt floor. We use a dehumidifier in this area. When I say moist, if we get an inch of rain there is water infiltration and during high humidity months its a typical northern basement. The dehumidifier is operating. Additionally, the dehumidifier is set towards the drier end of the setting and it does catch up and doesn't run continuously. That said I agree seasonally there will still be wide swings in RH and I will look into better or more frequent air communication between the 'old' and 'new' house with yr round conditioned air.

What is the "a table to compare the moisture content of the new flooring with how much expansion (width of each board on average) will occur " What will I do with this information?

Again, thanks to the contributors the feedback it is very helpful.

The width expansion of quarter sawn and rift sawn will be less than the width expansion of plain sawn boards.

Going over the existing strip flooring without taking it out will provide support for the staples. The staples will penetrate the sub-floor, also. Check to see if there is a moisture barrier under the strip flooring. There would usually be water-proof kraft.
If you check the existing strip flooring with a moisture meter (Harbor Freight sells them, and even though they may not be super accurate) and compare to the new wood you may get a difference if moisture content that may not be able to match, (which is what you would like before you start to lay the new flooring). If the two readings don't match you should be able to project the width that the new flooring will become with a certain difference in readings with a chart that averages the change in width for each difference in moisture content. Quarter-sawn flooring averages half the expansion or contraction of a plain-sawn board with changes of moisture content. A higher posture content between existing and new flooring would mean a change in width and can be predicted to widen with each difference in moisture content percentage and will be found in a table developed for each specie. I use this table, http://owic.oregonstate.edu/wood-shrink ... imator?f=1.