beefing up the floor

[TimG]

I want to beef up the main floor floor joists. When someone walks around you can feel things shaking a bit.

The basement is unfinished, which makes things a bit easier.

The current joists are 24" on center and engineered I-beams, not 2x8's.

What would be the best way to reinforce the floor?

[autosm]

Jayman house I bet?

I had same problem. Purchased 5/8 plywood and had it cut @ 8 feet x 8.75 inches. Then by gluing and screwing them to the fill in the I beam. Then added another 12" x 8 foot on top of that on both sides (way overkill) So now my floor joists are almost three inches of plywood plus the original joist. I staggered the joints of the 8 foot sections @ 4 feet.

I did both sides of the I beams that were accessible and only one side of the ones that had plumbing or wires attached.

Then I connected / cross braced all of the joists with 2x6 boxes and added plywood to span each 24" and connect them together.

Floor does not move. I did this to ensure I did not have an problems with the tile & hard wood that I installed after the above work.

[TimG]

no, it`s a cedarglen house.. about 10 years old.

[garnet]

so the issue is the floor having a 'bouncy' feel, rather than being 'skeaky'?

sometimes this can be present in an i-beam joist floor, because of a long span, even when meeting code for support with 12" beams
a lot of the time builders make this 'just' to code

ideally (if building a new home) it'd be nice to have a deeper beam for longer spans, and/or closer spaced beams (like 16" o.c.), better then minimum code required

there "should" already be blocking (bracing between the joists) in place, if not this can be done easily, and needs to reach across from end-to-end
proper method is to cut same size & material of blocks (12" tall), secured to the vertical, close together as possible (forming a sort of cross beam), 2x12" would work in this application, glue & screw it to be squeak free

another method some have tried is to box the beams (plywood horizontally to bottom of joists), but to be of any real help would have to cover the entire continuously, and it doesn't truly contribute anything to the vertical strengthing of the beams

the stongest method is to install a support cross-beam, located at center of span of joists, full width, and then support post/jack-post at each end and at mid-span...but this would be for a really bad sag issue IMO

[TimG]

I don`t think it`s so much that the existing joists are shaking. I think it;s more the fact that because of the 24`spacing you can feel the floor sag between the joists.

[C_Dave45]

Originally posted by TimG
I don`t think it`s so much that the existing joists are shaking. I think it;s more the fact that because of the 24`spacing you can feel the floor sag between the joists.

Are they 24"? Or 19.2's? The standard with engineered now, in most homes are 19.2, at least in all the CG's I work in. If you feel the whole floor kind of "shake, or vibrate" when someone heavy walks...or when you drop something heavy, that's more the span flexing, as opposed to sagging in between joists. 19.2 centers with a total of 1" plywood/OSB (5/8th's OSB + 3/8" ply) is more than strong enough for tile. I've installed 20x20 travertine marble over such, and never an issue. For extra insurance and peace of mind you can add an anti-fracture membrane when installing tile...but not necessary.

Doing what autosm did (although way overkill and not necessary for tile) will stop that overall "shake" but won't diminish any sagging between joists.
You could drive a tank across that floor lol.

[autosm]

I did not have any sagging issues just a bounce when you walked accross the floor. My Jayman home is 24 OC not 19.

I went over kill because I finished the basement and could not go back and add more if it was not good enough.

I first did the two in the middle joists and that alone made a huge improvement. The problem room is 20 x 13 feet. With about 12 feet of span where the problem was.

Forgot to add that I screwed a 2x6s to the underside of the floor to beef up the soft areas.

Over kill I know, but the floor is solid. Before if you were sitting on a couch in the room you could feel someone walk by.

[nismodrifter]

We had the same issue in our home and we fixed it in a manner similar to what autosm has described above. I can now jump on the kitchen floor and nothing rattles/vibrates like it used to. Took a long time to do the entire rear portion of the home but it has made a huge difference.

[tictactoe2004]

Originally posted by autosm
Jayman house I bet?

I had same problem. Purchased 5/8 plywood and had it cut @ 8 feet x 8.75 inches. Then by gluing and screwing them to the fill in the I beam. Then added another 12" x 8 foot on top of that on both sides (way overkill) So now my floor joists are almost three inches of plywood plus the original joist. I staggered the joints of the 8 foot sections @ 4 feet.

I did both sides of the I beams that were accessible and only one side of the ones that had plumbing or wires attached.

Then I connected / cross braced all of the joists with 2x6 boxes and added plywood to span each 24" and connect them together.

Floor does not move. I did this to ensure I did not have an problems with the tile & hard wood that I installed after the above work.

Awesome, I have the same problem with my kitchen/great room/nook area. I'm totally going to do that.

[garnet]

what he's refering to is basically laminating plywood to the vertical (osb) sides of the beam to "thicken" it's profile, which is better to added beam strength

that will work, lap the seams from side-to-side as mentioned


as a contractor i couldn't do that, being an engineered item, and it's not a recommended practise by the manufacturer.....but as a homeowner no one is to stop you of course ;)

[custom91yota]

Its always better to have solid lumber over osb find out the depth of the web of the joist and put in the lumber that fits eg.2x8,2x10 and the glue it with pl 400 and screw it together. Sometimes to strengthen the joist the manufactur only wants a 2x6 on the top cord the whole way it just bepends on their specs

[garnet]

?osb is the OEM material used for engineered beam construction, with 2x2/2x3 caps

to lap joint material onto the beam, be it plywood strips or dimensional wood, is not the recommended practise of the manufacturers
which means as a contractor i couldn't do this for a client, and to do so would be a swift way to make redundant my liability insurance LOL

more specifically, not without an engineering permit in hand, which they wouldn't do anyways, instead they would stipulate a cross-beam be used to support (as was described)

to lam up multiple pieces of timber along the length of the beam would be the more heavy & awkward method, not unlike gluing matchsticks together and using as beam

an engineered beam's strength over same span is better then dimensional timber in a vertical load, and it's strength is due to it's continuity of material along that length, as it's designed to be

however, a homeowner can do as they please, in which case to thicken the beams, to glue & screw ply (cut to the fullest height fit within beam and length 8') would have the better results for efforts made

[garnet]

?osb is the OEM material used for engineered beam construction, with 2x2/2x3 caps

to lap joint material onto the beam, be it plywood strips or dimensional wood, is not the recommended practise of the manufacturers
which means as a contractor i couldn't do this for a client, and to do so would be a swift way to make redundant my liability insurance LOL

more specifically, not without an engineering permit in hand, which they wouldn't do anyways, instead they would stipulate a cross-beam be used to support (as was described)

to lam up multiple pieces of timber along the length of the beam would be the more heavy & awkward method, not unlike gluing matchsticks together and using as beam

an engineered beam's strength over same span is better then dimensional timber in a vertical load, and it's strength is due to it's continuity of material along that length, as it's designed to be

however, a homeowner can do as they please, in which case to thicken the beams, to glue & screw ply (cut to the fullest height fit within beam and length 8') would have the better results for efforts made

[codetrap]

I screwed 1x2 strapping across the floor horizontally on the bottoms of the I beams. Also added in some blocking where I was getting the odd squeak between the I beams. I wanted to keep the overall weight down, and provide some lateral stability to better link the load sharing.

Probably not the best engineered solution, but it appears to have assisted with distributing the load and cutting down on the bounce. Also don't have any more squeaking.