Upstairs garage floor

[wrhenker]

I was wondering if anyone knew how to stabilize the floor on a 2 story garage with a 26 foot spread. I really do not desire to use post, but the floor is a bit flexible. I am planning on finishing the upstairs as a workout/rec room, but it makes me wonder. I do have some cross braces under the floor now, but it doesnt appear to be doing the trick. If I knew this would happen, I would have doubled up on the spreads! Steel beams are out of the question as well. Got any ideas?

 

[twostory]

The only way to fix the excessive floor deflection is more support.

If possible, can you add more floor joist (between your existing joist)? My garage is 26ft wide. For the 2nd story floor, I used 16 inch wooden I beam, 16" OC (26 ft span)

My floor does deflect, but NOT excessively. I am sure the 600# table saw in the middle of the span does not help.

 

[wrhenker]

I will try to add more support. Heck, just the weight of my mother-in-law makes it bow down 3"! Of course, she is no ballerina!

 

[Ray-CA]

You can do what is called "sistering" (doubling up the rafters.) If you can access the ends of the rafters, you should be able to slip an additional rafter in alongside each one. Then tie them into the floor.

Ray

 

[Justanoldguy]

Why do you say "Steel beams are out of the question as well." ?
A good size beam running under the joists at 90 degrees would solve all your problems.
Us an I beam and it can double as a gantry...

 

[Kevin54]

If you are serious about the floor deflecting 3", what thickmess of flooring do you have and what size of floor joist do you have? 3" is quite a bit of deflection. With a span like that you would need some kind of support underneath. Was the 2nd floor built with finishing off in mind or was the 2nd floor kind of an afterthought? What you may have to do is put an LVL beam underneath at the midpoint to support the upper structure if you don't want any post underneath. It will probably involve a little work to get it to set on each side on to the foundation especially if you have the lower portion finished off. You would have to cut out the wall covering, build up some bracing, jack the beam into place, then support under the other end. Either way...if the MIL bounces the floor 3", I would not want to be putting excercise equipment up there. You could also put a steel "I" beam under there and a trolley hoist...........

 

[wrhenker]

Hey, thanks for the ideas! I had a plan for the upstairs usage. But after the garage was built, I found a lot of problems. You see, I went with a "well known" garage builder and boy did they cut corners. The foundation has no footings, the interior cement edge along the walls near the front stick out past the wall on one side and after not even a year, I have a 2' crack from the front corner going towards the middle of the garage. All that, and I have "bounce" on the second floor, even without the MIL. With the foundation being bare minimum, I am shying away from more weight along the edge (steel beam). I know that planning is everything, but I had to work within a budget. I have 1/2 OSB for the flooring, 12" floor joist and planned on finishing it all off (wood, not drywall - unheated). Since I do not have an adequate cement floor, I guess steel beams wont work. It will crack even more for sure. Maybe support from above?

 

[Justanoldguy]

I would cut a couple of holes in the floor and dig some deep holes and fill them with concrete.
A couple of good posts buried in them while you are at it.
That would support your steel beam ans eliminate all your problems.