Hello from the Great White North! I am doing work on my twenty-five year old house and am now at the stage where I want to install hardwood floors in the living and dining areas. The house has what can best be described as an open-floor plan with the back of the house being one step down from the front. I have already installed porcelain tiles in the entry and hall areas with an underlayment of Durock cement board. This tiled area adjoins the living area and my intention is to have the wood floor at exactly the same level and running front to back. The problem is that the joists (2X8s 12 inch on centres) also run in that direction. I am looking at either solid wood S&B maple 2 1/4" wide and the standard 3/4" in thickness or an engineered product of the same type of wood that is 2 1/2" thick, both produced by Mercier here in Québec. I have issues with the subfloor (3/4" plywood that I have now screwed down to the joists) being less than flat, a few joists being higher than the rest, that I am in the process of addressing.

It appears that the manufacturers pretty well frown upon installations not running perpendicular to the joists.

Since the whole set-up would look pretty bad running the boards along the narrow dimension of the room (more so the dining area that is really rectangular, the living area being more or less square), I insist on having the floor lining up with the longer dimension of the room(s).

What are the issues that arise when installing in the same direction as the joists?

What can be done when installing to alleviate these problems?

I find the answers given on this board to be a precious resource, the manufacturers seeming to me to provide answers to limit their liability and the retailer’s answers to get product out the door.

Thanks.

If the joist are 12" OC and the 3/4 plywood has a T&G, I think you would be OK to run it parallel.

Absolutely. I agree. 3/4" plywood over joists 12" OC should be quite stiff enough. Just be sure to flatten the subfloors. One of the problems when running parallel is that if some joists are higher than others, you get a roll in the floor lengthwise that makes the floor very difficult to sand and it can be seen.

Thanks.
In fact I have two joists that are too high as well as a "droop" in the middle of the room, with the portion of the floor from the outside wall to about three feet in being also higher (in fact level with the higher joist(s)). I didn't concentrate too much when I initially checked the floor with an 8 foot straight edge, and was also under the impression that flat and level was a real issue only with ceramic tile... So I screwed and glued 1/4 inch Luan so the wood floor would be at the same level as the adjoining tiled entrance and only started to notice how uneven the subfloor was after. Then doing some research and asking some questions I realized that hardwood needs flat and level too. Since I didn't want to tear out what I had just put down, I decided to leave it there and build up from that level so that instead of 3/4 inch solid I now have to use 1/2 inch engineered.
To level the subfloor I am using a "technique" that I came up with years ago for the kitchen floor (I’m sure others have thought of it too) where I fill in the low spots with screwed and glued plywood patches, varying the thickness used to fit the site and pouring a final layer of Mapei self-levelling cement to even everything out. Now the manufacturer of the wood tells me that if I use cement I have to wait at least 30 days for it to cure and dry enough not to affect the wood. At this stage of the project, a delay of 30 days is a cause for divorce!

I also understand that if the Mapei is used I can forget nails or staples and would have to glue the floor, a prospect I am not too crazy with.

My question then is whether some kind of non cementious filler exists for this kind of situation. I was thinking of what is used in boat repairs or car repairs or something of that nature that is not mixed with water. I realize that “Plastic Wood” is too expensive for that type of job and probably not even usable as it is as noxious as anything in the home.

If not, I understand that I can use felt paper to fill in the transitions in my plywood "relief map" of a floor. My concern is that, even using different weights and adding layers of this paper, how can the whole thing be feathered out the way self-levelling cement does?

Any information would be greatly appreciated.

Thank you all.

PBB

With all that extra work and expense, I'd consider tearing out that 1/4" luan if that's the only thing that's creating a problem. If I came across a subfloor where some /a few of the joists are high, if possible, I'll remove the subfloor, plane down the offending joists and replace the subflooring. I'd still consider that in your situation. I've done the "plywood filing in low spots and then sanding it" routine. It works but it's too much work and the results are less than stellar, IMO. Better to use 3/4" flooring nailed down. And when you need to fill in low places, use asphalt roofing shingles and/or 30 lb. asphalt felt paper. Hey, but you're the one doing the work. Everyone has they're preferences. Perry "Austin Guy" prefers glue downs and I prefer nail down. It's what you get used to I suppose.

That sure saved me alot of typing .... what Gary said is the best method.