In my current abode they used floor trusses for both the first and second floor. From the basement I have easy access (for now) to the first floor trusses. They are great in that they allow for such a long span and a very open floor plan. However - there is a fair amount of bounce in the floors, especially when two kids get a little excited running around the house. This is especially true in the kitchen area which has cabinets all around, heavy appliances, island, etc. so I suspect that this added "normal" load makes them a little more flexible.
Does anyone have any suggestions for how to stiffen or strengthen these trusses? There is currently one strongback going across the trusses about mid-span between the supported ends. This isn't something that I am afraid has been under-engineered to start with. From my reading of some span tables, etc the spans are well within what they can be for that size of truss. I'm just looking to reduce the rattling of glasses/light fixtures, etc when the kids go jumping.
Some ideas I have had are:
1) Add additional strongbacks. How big is useful? Would a 2x6 do much or do I need a 2x10 or 2x12 before it does any good? Going around heating ducts and drain lines could prove somewhat a challenge to get bigger sized material in place.
2) Put in some kinds of cross-bracing between the trusses - like you normally see for normal joists. Allows for easier maneuvering around utilities. This of course begs the question - wood or metal.
3) Add plywood gussets on the truss sides where I can. Because of heating ducts, plumbing, etc, there are some places that I couldn't, but most places I could. Does it help/hurt to only do this on one side? Do the extra fasteners into the 2x4's hurt their strength?
4) Do some/any of the above after jacking up the center of the truss by a small amount (1/4" ??) so that the re-enforcing is taking the load right away.
Any other brainstorms?
Thanks - Dan