What's the Best Orientation for this Hardwood Floor?

Discussion in 'Hardwood and Laminates Q&A' started by LI Guy, Dec 8, 2017.

Which Way to Run the Solid Hardwood Floor With T&G Subfloor Perpendicular to Joists?

  1. Perpendicular to Subfloor, parallel to joists

    0 vote(s)
  2. Perpendicular to Joists, parallel to subfloor

  1. LI Guy

    LI Guy Member

    Hi guys, new to the forum here! We're in the process of remodeling/restoring this old house we bought last year. It's been fun, but a pain in the neck...Anyway, I'm getting ready to install hardwood flooring and I've run into a situation that's a real head-scratcher....I did some searching but haven't found anybody with this same situation, so I thought I would ask the flooring pros here.

    The house was built in 1916 and has what we thought were beautiful wood floors in the dining room and living room. The floors are 3-1/2" tongue and groove southern yellow pine. Upon further inspection, these boards are face nailed with exactly one common nail (not finish nail) per board per joist and are actually the subfloor.

    So we want to install 2-1/4" x 3/4" pre-finished oak flooring over this subfloor. The wrinkle is that the subfloor is installed perpendicular to the floor joists. Our original plan was to install the new floor perpendicular to the subfloor, making it parallel to the joists, then I read that the finish floor should ALWAYS be perpendicular to the joists, even if it means it's parallel to the subfloor boards.

    Most of what I can find on the net talks about plank subfloors that run 45* to the joists, but nobody seems to have a T&G subfloor. In the upstairs, the joist orientation and subflooring are the same. In two bedrooms, oak flooring has been there for many years and runs perpendicular to the subfloor but parallel to the joists. In the hallway, it runs perpendicular to the joists. We added hard wood to the master bedroom, and the company that installed it ran it perpendicular to the joists, which is parallel to the subfloor boards. Both ways seem fine.

    Some additional info:

    The house has a full basement that's dry as a bone. When we bought the house last summer we added a dehumidifier to the basement so it's even drier now. Floor joists are 2x8, 16" O.C. This was back when they measured a true 2" x 8"....joists are strapped but not blocked.

    In all cases the subfloors are flat, no cupping, and minimal squeaks, so I don't see any need to install plywood, the big question is which way to run the floor, perpendicular to the subfloor or perpendicular to the joists??
  2. Jim McClain

    Jim McClain Owner/Founder Administrator

    Dry as a bone to you, apparently, isn't dry to the bone actually because you felt a need to add a humidifier. It prob'ly means something different to a lot of people, which is why we like numbers/percentages, not what you think it is. You need to know the moisture content of the subfloor and the hardwood too.

    You need plywood underlayment because your subfloor is 3-1/2" tongue and groove southern yellow pine, nailed perpendicular to the joists with a single nail on each end, not on an angle and not subfloor panels.

    I would add at least one nail to each end of the subfloor planks to make it sturdier and to remove any squeaks. Then, depending on the thickness of the subfloor, I would add a 3/8" (minimum thickness) underlayment panel to the subfloor with staples long enough to go almost through the subfloor. New hardwood is next, perpendicular to the joists. If you prefer the direction be parallel, then more steps must be taken to prepare for that.
  3. LI Guy

    LI Guy Member

    Hi Jim thanks for the fast response! The basement was interesting...the previous owners had finished part of it with drywall and carpeting on the floor. Under the carpeting, they Dry-Lok'd the cement and then added plastic sheeting under the carpet. The double barrier trapped moisture and the basement had a dank musty smell. After we gutted everything, we got the dehumidifier to dry everything out, and I installed it with a permanent drain so it can stay on and cycle as needed to maintain 50% RH. (It has a built-in condensate pump and drains to the laundry sink.)

    We've been here 15 months now and no water incursion or seepage at all, and no more musty smell. So dry as a bone now, but wasn't always. Since the subfloor is open to conditioned air on the first floor (we had central a/c installed) and dehumidified air below, even if I had a moisture meter I'm not sure how I could get the floor any drier.

    The hardwood installed upstairs looks like it has rosin paper under it, and that's it...no prep work was done to the subfloor and we have no sags or squeaks....so I'm not sure what I would gain from adding plywood other than floor height.

    It sounds like plywood or not I need to install perpendicular to the joists though.
  4. Jim McClain

    Jim McClain Owner/Founder Administrator

    I'm just a retired floor guy with 35 years of experience, so I may not be right, but I wouldn't touch that job if it couldn't be done with a layer of underlayment over the 100 year old subfloor you have. Even if it was only 10 years old, it's a stripwood floor over joists. It's not a proper subfloor.

    If you want to gamble the cost and longevity of a decent hardwood floor on your reluctance to install some relatively cheap insurance; well, it's your money.
    • Agree Agree x 1
  5. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    from: National Wood Flooring Association, Subfloor Guidelines & Specifications ©2007 l Revised 09.2012

    "Solid board subflooring should be: ¾” x 5½” (1” x 6”), Group 1 dense softwoods (SYP, Doug Fir, Larch, etc.), No. 2 Common, kiln-dried to less than 15% MC."

    "Solid-board subflooring should consist of boards no wider than 6 inches, installed on a 45-degree angle, with all board ends full bearing on the joists and fastened with minimum 8d rosin-coated or ring-shanked nails, or equivalent."

    The reason strip and plank flooring is to be installed perpendicular to the joists is strength. It prevents sagging between the joints, which will ultimately result in squeaks or other undesirable noises.

    The reason for installing perpendicular to a previous strip or plank floor is to prevent gapping at the edges due to changes in moisture content with changes in relative humidity, within the specified guidelines.

    You are left with two options for a successful installation. 1) Install your flooring on a 45% angle. or 2) Add a layer of plywood.
    • Informative Informative x 1
  6. LI Guy

    LI Guy Member

    Thanks for the info guys! I tried to post some pics of the room and subfloor but forum rules wouldn't let me.

    I got some new info as I was tiling the bathroom floor upstairs yesterday....the bathroom is at the end of the hallway upstairs, and the hallway has wood flooring that runs perpendicular to the joists, and parallel to the subfloor. Looking at the ends of the boards, you can see that there is a layer of 3/8" thick by about 10" wide boards between the wood floor and the subfloor. I am guessing that's what they used before plywood was invented.

    I wasn't here when they installed the wood floor in the master bedroom last year, but my wife says they used 3/8" plywood to make the height of the finished floor match the hallway. Whether the flooring installer would have used plywood if there wasn't a height issue is anyone's guess. I will say the floor is rock solid so there is no arguing with the results. He also did a great job finishing it.

    So I stand corrected on all accounts here...

    If I understand correctly, the correct installation here would be 3/8" plywood over the subfloor, then install the finish floor perpendicular to the joists. So the plywood then negates the effects of having the finish floor parallel to the subfloor boards. Makes sense.

    What's should I be using between the finish floor and the plywood? Should I use a rosin paper or a tar felt paper like they use for roofing underlayment?
  7. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    Rosin paper is not an approved vapor retarder.

    Most guys use 15 lb roofing felt or Aquabar B. Aquabar® B - Fortifiber
  8. Jim McClain

    Jim McClain Owner/Founder Administrator

    The only place you can't post photos is the media galleries and the personal messaging system. You can post photos all day long in any post you make on the forum. In the message editor, at the bottom edge, you will see a big red button that says Upload Photos or PDF.
  9. LI Guy

    LI Guy Member

    Sorry I was getting an error to the effect that "It looks like you are posting dangerous code" because the photos are hosted on PB. Anyway it looks like they posted OK.

    li-guy_zpsgvtdnn2v.jpg li-guy_zpshcmf1yj1.jpg li-guy_zpsueytthxr.jpg li-guy_zpswbytpjpw.jpg li-guy_zpsytsihsg9.jpg
  10. LI Guy

    LI Guy Member

    Another new wrinkle, the electrical outlets are installed old style sideways in the baseboard. I don't have the height I need for the outlets to clear the shoe moulding if I add 3/8 plywood.

    Help me understand what the risks are of skipping the plywood. Also, if I did 1/4" ply is that better than nothing or a useless waste of money?
  11. Jim McClain

    Jim McClain Owner/Founder Administrator

    That's because PhotoBucket (and every other "free" photo hosting site) sucks. Either you or they will somehow prevent those images from being seen sometime in the future. You may find help solving your problem, but many visitors to come throughout the years will not have that advantage when your photos are no longer visible. We have our own photo upload system and ask all our members to use it. It's free and easy enough to use.
  12. Jim McClain

    Jim McClain Owner/Founder Administrator

    I believe you have been provided enough information to understand the importance of a plywood underlayment. If you are in search of validation for making a mistake you seem to be finding excuses to make, you would only find that on forums that offer a lot of other DIYers' advice. The advice you have received so far has come from an accumulation of about 75 years of experience - one of the pros (not me) has extensive experience in milling and inspections, as well as installations.

    Is quarter-inch better than nothing? Obviously, but the advice you have received is what we would do. You have pretty tall baseboards that has plenty of room to move your outlets up a half-inch or so. Ask a pro electrician for advice on that.

    After looking at your photos of the existing flooring and the new boards, I'm wondering :hmmm: why you aren't refinishing the existing, historical, beautifully patinaed Southern Yellow Pine flooring? I would be removing all the common nails that were probably added later to quiet squeaks and add a couple 16 gauge finish nails, countersunk and filled. Then sand and finish the floor. Then add an inch or more of spray foam insulation to the flooring between the joist cavities. That will add R-value and quiet any persistent squeaks. You won't have to change the outlets or add quarter-round (I would add base shoe anyway, just because I like the look on tall base).

    You already have a floor that is probably better than the new stuff you bought.
    • Agree Agree x 1
  13. LI Guy

    LI Guy Member

    Jim, that's a fantastic suggestion! What would be the best way to remove those nails without scarring the wood? Between the living and dining rooms there are at least 1000 nails...if I try to get under them with a pry bar it will most certainly take a divot from the wood. The joist bays are open underneath from the basement so I could easily add the spray foam insulation.
  14. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    Crescent nail puller will get them out. Question is: Is that how the planks are fastened to the joists/ subfloor as opposed to typical blind nailing?
  15. LI Guy

    LI Guy Member

    That's an excellent question...I don't know if that's how the floor was originally installed, or if those nails were added later to quiet squeaks. In any event, pulling those nails and repairing the damage as part of a re-surface is just not in the timeline or budget right now.

    After doing some additional research, we decided to install the floor perpendicular to the existing subfloor and parallel to the floor joists with a layer of 15 lb felt paper in between. This was how the original hardwood floor was installed when the house was built.

    One thing that was pointed out here is that the floor makes its strength along its length, not across its width. So running parallel to the joists has added an incredible amount of stiffness to the floor and taken a lot of the bounce out of it, since the strength of the floor is now adding to the strength of the joist span.

    We had no previous squeaks at all in the subfloor and no sag at all between the joists, so it's not likely that adding a hardwood floor will either cause squeaks or suddenly cause the subfloor to sag between the joists. There is absolutely no reason add a layer of plywood in this application.

    Talking about about "professional advice" I'm thinking that the collective experience here is built around eliminating callbacks....when in doubt, add a layer of 1/2" plywood. Heck, our previous house was a 5 bedroom colonial built in 1973 and the entire second floor was 2-1/4" oak over 1/2" plywood subfloor, and zero issues with that floor all the years we lived there.

  16. Jim McClain

    Jim McClain Owner/Founder Administrator

    Well, we can't convince everyone to do the job right. It's your house, your time and your money. But I doubt the source of that research was from a true flooring professional. I'm glad you're satisfied though. Enjoy the new floor.
  17. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    No kidding?!?!? I damn sure would not knowingly give you advice that has been proven to result in failure, or as you call it callbacks.
    • Like Like x 1
  18. LI Guy

    LI Guy Member

    Hi Dan...sorry you misinterpreted my comments, I was NOT inferring that you would give subpar advice. What I was saying is that since it's difficult for you to judge the quality of the subfloor without being on site, the safe advice is to put down plywood, that would guarantee I wouldn't have any problems. Without plywood, I may or may not have problems.

    How long would it take for an incorrect installation to fail? Is there a point where if it hasn't failed it won't? Let me know what timeframe would be appropriate to post back with pics, and I'll do so, good, bad or ugly. Right now it looks great, and as I said, running across the subfloor and parallel to the joists has taken a lot of the bounce out of the floor overall.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.