My wife and I are going to install 3/4 Bruce Kennedale strip in our family and living rooms. The total size is abou 440 sq ft. (33 ft NS, and 13 ft EW) For the most part the joists are running NS. On the E side, all joists run the full length NS. However, the W side is broken up into 3rds. The middle thrid has joists running EW, (these run out of the house and form the joists for the outside deck. (the joists are 16 inches appart).

The subfloor is 3/4 plywood.

If we don't do anything else to the subfloor, are we limited to running the hardwood at 45 degrees? (or isn't this even recommended?)

What do we need to do to the subfloor to be able to run NS or EW? For the EW case are we safe as is, given that a majority of the joists run NS? What about the case were we run the strips NS, do we need to install another 3/4 of plywood?

additionally, because of the odd joist arrangement the W side slopes away, is it all right to just build this up with builders felt?

Thanks!

Sheet the whole area with 1/2" plywood either well stapled or nailed and glued. Then run the floor any direction you want. Subfloor must be flat 3/16" within 10' radius. If an area is low, use felt or thin plywood to shim up even, then lay 1/2" CDX ply.

If you have access to the joists, you can add bracing every 16 inches between the joists that are the wrong direction. 2 x 4s are good enough, you just need enough strength to keep the ply from bending over time. They must be securly fastened or they can be the source of some nasty squeeking later on. There are a number of ways.

Otherwise another layer of ply or 45 degrees.

I was always taught like Marco, to lay the next layer of plywood, at a 45º to the existing sheets.

Thanks Guys!

Just a couple questions for clarification:

1) so if we just do the strips at 45 degrees, we will still be structurally sound?

2) If I put 1/2" plywood down, I should level first with felt. Do I need to put a layer of felt on top of the new 1/2" ply as well?

3) Any pics on the idea to brace with 2x4s? Are these just 16 inch long 2x4s that are placed between joists (perpindicular). Do you nail/screw to joists and plywood?

Thanks Again!

1. Yes

2. No, if you have covered it completely under the 1/2".

3. No photos. The 2xs would be 14.5 inches assuming a perfect 16 center. The ends should be toe nailed into both joists and screwed from the top. A nail gun or palm nailer(don't know how I ever lived without one) make quick work of it. Wouldn't hurt to use a little Liquid Nails on the top edge. Then a screw or two from the top. Good solid floor.

1. Yes

2. No, if you have covered it completely under the 1/2".

3. No photos. The 2xs would be 14.5 inches assuming a perfect 16 center. The ends should be toe nailed into both joists and screwed from the top. A nail gun or palm nailer(don't know how I ever lived without one) make quick work of it. Wouldn't hurt to use a little Liquid Nails on the top edge. Then a screw or two from the top. Good solid floor.

1. Yes

2. No, if you have covered it completely under the 1/2".

3. No photos. The 2xs would be 14.5 inches assuming a perfect 16 center. The ends should be toe nailed into both joists and screwed from the top. A nail gun or palm nailer(don't know how I ever lived without one) make quick work of it. Wouldn't hurt to use a little Liquid Nails on the top edge. Then a screw or two from the top. Good solid floor.

1.) Yes


2.) I have always been taught that felt between wood. Not for moisture resistence, but for squeaks that can develop when wood is on wood, without being laminated.


3.) Yes, but I like to use wood of the same dimensions as the joists, or use 2, 2x4's one at the top and one at the bottom of the joist. It's not as stout as a board the same dimensions as the joist, but better then just a 2x4 on a 2x12 floor joist.

1. Yes

2. No, if you have covered it completely under the 1/2".

3. No photos. The 2xs would be 14.5 inches assuming a perfect 16 center. The ends should be toe nailed into both joists and screwed from the top. A nail gun or palm nailer(don't know how I ever lived without one) make quick work of it. Wouldn't hurt to use a little Liquid Nails on the top edge. Then a screw or two from the top. Good solid floor.

Once again, thanks.

one issue i just realized with installing the additional 1/2" plywood. If I do this I have a transition into the kitchen which will be about 1 1/4" below the hardwood, (1/2" ply + 3/4" hardwood).

Originally I was just going to use a reducer strip, any thoughts on how to handle the larger drop off?

I would put felt under the wood too just because I think it provides a slightly softer, quieter surface but wasn't the question..... Hadn't heard that about squeeks. I went to Bruce school once and they didn't feel anything was necessary under the wood. Typically I use kraft paper because its easier to slide the wood.

As for 2 x4s or 2 x 10s, I have seen floors laid parallel with the joists on 3/4 ply that have no sign of dipping between the joists. I'm sure it could happen though and always felt confident a 14.5 inch span of 2 x 4 would be enough to support 40 lbs/sq in.(at least as much as a 1/2 layer of plywood). I don't have the numbers here though to support that argument. I do know that when working in 18" crawl space, when cutting and nailing around pipes and wires to warped joists, the 2 x 4 makes things a lot easier.
If our poster is dealing with a small crawlspace heres a big tip, lay plastic under the house as you go. Instant moisture barrier and much much easier and cleaner work environment.

You may have to do some kind of custom double reducer. Table saw required. May need some stain and finish to match an open cut-depending.
A big reason why the other options might be better.
With the 45 deg, don't forget to allow about 5% more for waste on the end cuts.