question about fixing a springy floor

[Jason]

Hi all, I've got a 16 year old house with a springy floor. We're looking to fix the floor before installing hardwoods and I wanted to get some opininos on which of my possible courses might be best.

______ |----/ | \----| | 15.7 |13.7 | | |----------------| 21.10

The room is 21'10" X 13'7" with a cantelevered bay window mid-way on the long wall. The joists are 2x8s 16"oc. As you might expect, the floor is extremely bouncy. We want to put down hardwoods so we need to remedy this.

This room sits over the garage, so a beam underneath isn't a really an option.

After doing a little reading on the net I learned that sistering might be a good option. maybe sister in 2x10s along side the old 2x8s.

Then after a little more reading, I hear bridging might be a better option?

Given those specs, can anyong give me a good idea of what my best option here is? Either mine or your own. Thanks!

[Brikp]

I just got my copy of fine homebuilding and there was an article about stiffening a floor. I just skimmed it so I'm not sure it would apply. There was reference to I joists but it may apply to conventional framing too. They said no on the bridging I think. Read it, I, obviously, didn't read it closely.

[John]

You'll find it difficult to sister a 2x10 onto a 2x8 when there is only enough room for a 2x8.

[Bob Morrison]

Sister on another 2x8 x 12'-0" centered on the 13'-7" span. Glue and nail w/ 2 rows 8d @ 8" o/c or use 1/4" x 3" SDS screws @ 16" o/c

[default]

Not really, the place the extra stiffness is needed is in the middle of the span, not at the ends, so he could certainly get away with notching the 2x10s and could probably get away with just cutting them short at each end.

That said, I think he gave to quickly on the mid-span supporting beam. Why is the fact that it's over a garage a problem? The beam doesn't need to be centered, nor are you limited to just one. And hell, they don't even need to be square with the foundation, really. There is almost certainly a way to arrange things so that you don't have a post coming down in an inconvenient place.

--Goedjn

[GLT]

Bob, why would you advice the sisters be nailed with 8's..? 2 2X's put together are 3" thick, IF they aren't bowed..A 8d is only 21/4" long, so why not use 16's at 3 1/4" long...? Even 10's would seem to be better than 8's.

[John]

What I ment was if he has a subfloor, a 2x8, and the fire retardant drywall above the garage thats below a living area, he wouldn't have the width needed for a 2x10.

[Jason]

The plan, if I went that route, was to notch the ends down to 8" so they would fit. I have plenty of clearance for them to hang down an additional 2"'s. Thanks for the reply.

[Jason]

Oh, there's no fireboard in place there. It's just joists with the subfloor on top. THanks!

[Jason]

Thanks for the reply!

It's actually a two car garage. All of the garage door/opener hardware is in the way of a potential beam. Plus I think there would likely be clearance issues for the doors themselves. The one place we could put a beam is where the door hardware ends. But that would only cut about

3ft off the span.

I certainly don't have the knowledge to say whether a beam in this location would offer more stiffness than sistering more material in there. IF you think that would offer more stiffness than sistering new joists, I am open to that idea.

Thanks again

[Bob Morrison]

The nails are there to hold the assembly together until the the glue dries. Remember, I said, "glue and nail..."

[Tom Baker]

While I'm going to school on this, what glue type would you recommend? TB

[Bob Morrison]

Tom:

I usually recommend regular old "construction adhesive" like that used for gluing down floor sheathing before nailing. It can be had in large quantities for a relatively cheap cost and it comes in a caulking gun tube for easy installation.

[willshak]

I have a triple 2x12 beam running across my garage ceiling parallel to the garage doors and 5'7" from the doors. My garage door track is doubled at the top so that the top most roller of the door uses the top track and all others use the track below that. This was necessary because of the low ceiling in the garage. The height of the ceiling at the doors is 8'4". The height of the ceiling at the front of the triple 2x12 beam is 8'2". The height from the floor to the bottom of the triple 2x12 (sheet rocked) beam is 7'7".

[willshak]

My mistake. It is a triple 2x8, not a 2x12.

[Jason]

Thanks for the advice!