TJ 110 with 15′ span on 19″ centers. Simple walking creates too much shaking in the kitchen. so just going to fix this after 5 years of being annoyed with it. This is the longest span in the house, of course is the ‘busy’ kitchen and underneath is the open rumpus room. So, I’m faced with choices, should I strap a couple of TJ’s to the side of the existing TJ’s under the primary ‘walking’ area in the kitchen (essential on either side of the island), block that same area on two sides of the ‘primary’ TJ’s that’s taking the direct load at say 5′ & 10′ in the span, strapping, or a combination of some or all?
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Replies
Doubling won't be enough
I assume a beam midspan is out of the question, although that is the best solution
Although you MIGHT feel a small differance in stiffness by doubling a couple of the joists, it will be subjective at best.
Possibly the next best solution would be to double the joists but with a taller I-joist or even LVL. This would create some issues with bearing at the ends though.
You will always get better performance with deeper joists - or shorter spans.
Terry
don't know for sure....but i've got a similar situation under a stone fireplace.....want to beef up the joists. .......i was planning on gluing and screwing plywood to the TGI's to create a "box-beam" effect. you could do it on both sides of the flange to create a triple web effect. i think that would stiffen that joist significantly.
What has the supplier/manufacturer suggested?
You mention the span, centers and series, but not the height of the joist.
These are engineered members and I would start out by contacting the company that makes them. Usually if you get close to maxing out the suggested span you will have bounce, thus they steer you to deeper members. However, when the same thickness joists are used over a foundation where the spans change, you find it easier to notice bounce, where if they all were supported evenly, any deflection wouldn't be called attention to.
At this point in the function of the home, the options of mid beam, deeper and shorter are not an option. The spans were designed to meet specs but unfortunatley don't meet mine or more importantly the wifes. In discussions with the supplier they figured another ibeam (tough to get installed with lots of hammering, etc), blocking and strappping could all help and maybe in the end that is what will happen. The web-box idea came to my mind last night too and I threw that by the supplier and he figured that might help. I wonder if screwed to the upper and lower cords, or alternately, inserted between the two cords and screwed to the original web, which would be better? I figure when screwed on the cords its the screws talking the stress, but when inside it is the material & screws. Also thinking it has to be a mirror image so whatever it has to be on both sides or pressure might twist the ibeam somewhat for just another problem, but that where strapping/blocking could help too.
For all you out there, faced with longer spans go with deeper ibeams and/or closer OC joists for lessor bounce free floor. there is less complaining in living on a stronger structure. Live and learn.
strapping all under at 16" oc