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zel 05-14-2007 05:00 PM

3/4" hardwood, same direction as joists?
We will be installing 3/4" Brazillian Redwood in the master bedroom in a few weeks. The joists are 2' apart and there is 3/4" plywood over them. There appears to be slight sagging in between the joists. Not severe, but enough to notice if looking across them. I know it is highly recommended to run the hardwood perpendicular to the joists, but if given a choice, we would really prefer to run them in the same direction as the joists. What are the short/long term issues associated with running them parallel to the joists? What if anything, can be done to safely run them parallel to the joists?

Big Dave 05-14-2007 07:14 PM

If you can see a sag between the joist now it will only be magnified once you put a shiny new floor on it.

I know you want to run it the same was as the joist but your just asking for it. Do it right and only do it once and you'll be happy in the long run.

zel 05-14-2007 07:25 PM

Thanks for the reply. I'm just wondering if there is any repair or modification I can do to the subfloor or joists to make it possible to safely run the hardwood parallel?

Big Dave 05-14-2007 07:38 PM

In my opinion to make the floor good enough to run parallel with the joist would take too much money, time and hard work. I'm shocked to hear that the joist are 2 feet on center. That is most of your problem. In my opinion to fix it you would need to add another joist between the ones you have to give enough support and take out the sag but that is not a guarantee.

zel 05-14-2007 08:30 PM

Ok, thanks for the info. They are 2' oc. The only good thing about them, is the 2x4's are turned so the 3.5" side is facing up, so there is a larger nailing surface.

Big Dave 05-14-2007 08:34 PM

Well now I'm lost. Why are there 2x4's in the floor? A picture might be helpful.

jproffer 05-14-2007 09:52 PM

Lost here too. My very first thought after reading about the 2x4's was that your joists were 2x4's turned on their sides, but........naaaaaa that CAN'T possibly be.

That's not called a floor...that's called a trampoline.:jester:

Full size (the size of the joists) blocking in between the joists every 16" O.C. would be my first choice if I just had to have the hardwood running parallel with the joists.

zel 05-15-2007 05:55 AM

The house was built in the late 80's. It has, what I'm guessing are prebuilt floor joist systems built with 2x4's theres vertical and diagonal 2x4's every couple feet. I will go dwn the basement and snap a pic to show what I mean.

zel 05-15-2007 06:23 AM

Ok, heres a quick picture I took of the floor joist system they used in these houses.

NateHanson 05-15-2007 09:09 AM

My house is the same - trussed 2x4 joists, 24" OC - and I have no sag or spring in the floors. I've been very happy with the strength of our trussed joist system, and it makes fishing wires, etc very easy between floors.

How thick is your decking? I've got 3/4" plywood, and haven't noticed any sag or spring.

zel 05-15-2007 02:49 PM

The plywood is 3/4" as well. I have to be honest here a second. The master bath is where I noticed the sagging, I havent actually checked the master bedroom, I just made the assumption that there would be some, due to the 24" OC joists, and from seeing some sag in the bathroom. I also know that there were squeaking problems with the floor after the houses were built and the previous owner had to have the builder come back and add alot of screws to the floor in various places to try and fix the problem. I still have squeaks that I'll be chasing soon.

When there was sagging in the bathroom, I noticed it was primarily noticeable where 2 sheets of plywood came together, they seemed high at the seem and low on the very next joists.

Zero Punch 05-15-2007 04:54 PM

Zel, I have the same truss joist system with 3/4 T&G in my town home. Ran my 3/4 x 3 1/4 maple parallel to the trusses . Me Bad. :thumbup: Will it last fifty years? I'll be long gone one way or another. It's been down 3yrs no problem.

zel 05-15-2007 04:58 PM

ZP, thanks, can you see any sagging or joint separation?

Zero Punch 05-15-2007 08:50 PM

No shrinkage, it's tight. Stapled about every 8 inches.
I also installed oak in the family room that runs across the joists I can't tell any difference other than the wife likes the maple better. :thumbsup:

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