I’m building my own timberframe/hybrid house. The ceiling/floor purlins are approx 3′-9″ o.c.
For various reasons, I’d like to install 3/4″ maple T&G on top of the purlins for the kitchen ceiling, then apply 3/4″ black walnut T&G on top of the maple for the flooring of the master bedroom above the kitchen.
Questions:
Should I install 1/2″ sub-floor material between the two flooring materials?
Should I run the two flooring materials parrallel to or perpendicular to each other with or without the 1/2″ sub-floor material? (My guess is that I shouldn’t give any of the combination of materials due to different rates of movement. Yes, No?)
I thought the 1/2″ sub-floor material on top of the maple could be used to blind screw to the maple and top layer of walnut in between the 3′-9″ purlin spans to tighten that up. Yes, No?
Should I use 15# felt between layers to reduce friction squeaks? Is there a better material/technique to lesson noise? If I use any material, would using it on each side of the 1/2″ sub-floor cause a condensation problem?
I am installing a dehumidifier, possibly with an air exchanger to stabilize humidity levels.
Replies
When I saw this post, I thought "Finally, someone stepped into my kitchen where I might actually know something." Oh, well. Without my tables handy, I would have to think that 3/4" T&G on app. 3' clear span is not thick enough to hold the load. Even if you put a layer of plywood, then the second layer of 3/4" T&G, the "sandwich" you are creating would have to act as a unit to have a chance. With 2 layers of 3/4" T&G and a layer of plywood cream filling, you are approaching the thickness required for a 3' clear span. I bet my tables would call for 2" T&G, which you are sortof talking about.
Answers:
I would definitely use plywood inbetween layers, and I would use 3/4" for extra stiffness.
Run the T&G layers parallel to each other. Otherwise, one layer provides no support. The plywood will help tie them together.
Definitely blind-screw the T&G into the plywood. If you choose to build it this way, you are in effect creating your own stress-skin panels. You have to bind the two outer layers together. I would glue and screw.
If you glue, of course you can't use felt paper. The felt paper is a bad idea, I think. It would trap any moisture in the wood. If it is preventing noise, it is because your floor is deflecting too much.
I'll check my tables tomorrow, but I think if you keep it as a 3' clear span, you need some thicker wood (2 or 3 inch thick) inbetween the T&G layers that would bear the load by itself, and then treat the T&G as non-load bearing. That way, you build in a safety factor. Alternately, you could add some cross-purlins or floor joists on closer centers to shorten the span. Have fun.
Definitely glue all layers together for the sandwhich with all layers running the same direction.
Keep in mind that the wlanut is a very strong wood. I don't know if they include it in these kind of structural tables tyupically..
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius
So this 3/4" maple is long enough to span the 3'9" or will it stagger joints? Same Q for the wlanut flooring? Whether you land all joints on the purlins makes a diff in the load bearing cpacity.
I would use construction adhesive to apply another layer of structural material, either 3/4" plywood or some #3 Pine boards. Then I would glue down a layer of Homasote. Then I would install the finished walnut flooring. The Homasote will help keep noise transmissions down to a tolerable level while the layer between finishes will help you avoid sagging.
Excellence is its own reward!
"The first rule is to keep an untroubled spirit.
The second is to look things in the face and know them for what they are."
--Marcus Aurelius