You can use PL glue and "sister" in wood over the webb. I did some and just cut 3/4 ply to fit over the OSB and used 1.5" screws. For a bag that will add alot of stress during work out I agree with the lateral bracing.

 

Can you hang the bag near a wall ? That way, you can make or buy a wall bracket to hang it.

 

You can use PL glue and "sister" in wood over the webb. I did some and just cut 3/4 ply to fit over the OSB and used 1.5" screws. For a bag that will add alot of stress during work out I agree with the lateral bracing.

- ChefHDAN

So help me clarify this. Add some 3/4 plywood on both sides of the OSB wedding then just screw the bag mount to the i-joist and add 2×6 or similar lateral bracing. That would make it similar to my previous install.

OR

Add some 3/4" plywood to each side of the OSB webbing then put two sandwiched 2×6's between the i-joists mounting the bag mount to the sandwiched 2×6's?

Would't the sandwiched 2×6's help 1/2 the load since it would be between two i-joists?

 

Can you hang the bag near a wall ? That way, you can make or buy a wall bracket to hang it.

- Lazyman

While this would be ideal, we plan on finishing the basement so the exposed walls will be framed in.

 

My house was built in the mid 80's and has those in it too. I hate them. That OSB is soft and kinda spongy. I would think for a heavy bag they would need a lot of reinforcement, so I would buy a sheet of decent quality 3/4" plywood to fill in. Cut it lengthwise with strips that will just fit in, then glue the livin' crap out of them, and finish off with a buttload of 1/4" carriage bolts. I 'm sure you are probably already aware that if there is anyone in the space above, they will not be loving you while you are using the bag.

 

These joists are well engineered, but you don't want a hanging load that puts excessive weight anywhere in tension.

Ideally for hanging, you would have the hanger loop over the top flange to avoid tension in the glue joints.
Simson I believe makes joist hangers for these where they normally attach to the cross beams. Using one of these inverted would carry the load properly. Usually the big-box stores have aisle sections with all these type of hangers.

 

These joists are well engineered, but you don t want a hanging load that puts excessive weight anywhere in tension.

Ideally for hanging, you would have the hanger loop over the top flange to avoid tension in the glue joints.
Simson I believe makes joist hangers for these where they normally attach to the cross beams. Using one of these inverted would carry the load properly. Usually the big-box stores have aisle sections with all these type of hangers.

- splintergroup

So something like this:

 

Close, but if you want to hang something mid span you'll need something more like this: (use upside down)

Simpson I-joist hanger

 

In agreement the trusses are engineered for the load that was specked out by the person who did the load calc. In that there has to be a fudge factor, so each one can take on more than what is expected of it as it's been put into use. I would leave them alone, because doing it wrong could weaken what you have.

Instead of changing the truss/joist, instead spread out the load you are adding by Sistering several trusses via a 2x whatever screwed into each truss/joist that you pass. So instead of hanging a dynamic weight from one lonely spot, you are spreading it across several joists in your case, so each one only receives a part of the total load you are adding. If the weight is great, you can build up a system of parallel 2x's then crossing 2x's coming to something like an upside down pyramid, with your weight suspended evenly in the center.

Know that a 2×4 is much less able to support, or hang a load from than a 2×12. Knots are not your friend, they are a weakness, so even if you have to buy more expensive lumber, it's worth it here. Typically 2×8 and up is much cleaner to begin with than a 2×4. Rather than eye screws that can back out, and unseat themselves using through bolts for the actual hang are stronger. Stronger yet when a metal plate is used to spread the load across the actual attachment point.

 

This shows the basic reasoning behind only "top-loading" heavy weights where you are using a single I-joist for hanging:

Thinking a bit more on your idea (where you intend to hang the bag between two parallel I-joists), You would want to use a hangar shaped like what I showed above, but oriented as shown in the picture.

Hang this arrangement on the sides of the joists with the top flanges hooked over the joists top flange and secured. Your cross support between the joists would cradle in the hangers. This would carry the load onto the I-joists properly.
This photo shows standard 2x joists, but I-joists need backing in the web area for attachment.

Installing 2×4's on both sides of the webbing (running between the top and bottom flanges) gives you an attachment surface for the drop portion of the hangers. You can secure these 2×4's (or even 2×6's) to the webs by drilling through the 2x's and webbing for bolts.

 

Can you hang the bag near a wall ? That way, you can make or buy a wall bracket to hang it.

- Lazyman

While this would be ideal, we plan on finishing the basement so the exposed walls will be framed in.

- SnyperX

I think that I would still take this approach. Just move the bracket to the new wall when you get around to framing it in later. I don't think I would want 100 lbs suspended from those joists especially far out from the wall. People above are likely to feel every punch.

 

I would glue and screw a 2X4 up and down snugly between the top and bottom flange, both sides in 3 bays. Make sure these are in a strait row, 6 pieces. Then cut OSB to fit from joist web to web and glue and screw it to both sides of the blocks you just put in. Now you have a box that can't move laterally, and would have to pull down 3 I-Joist to move at all. Run a 2×6, or 2X8 under that box to hang the bag from.

You could glue a block to the floor above and run one between the flanges to make it super strong, but I don't know if that will be needed.

 

Some good suggestions above. When I hung my heavy bag, I also used an old fan belt and a shackle between the chain and the joists. Amazing how much more quiet it is for those in the house that don't want to hear you hitting it.