Flooring – Is this a floor framing system? what is the difference between joist splices and floor joists

Since you can get to the floor from underneath, you can shore up the flooring by adding new joists between the existing ones. This will not be a FUN process, but the process is simple enough, just labor intensive.

First, add cross braces between each joist at each end, of the same dimensions as your existing joists. You'll want them to be snug fitting between each joist, and well supported with joist hangers.

Now, between each brace, halfway between each existing joist, hang new joists to fit between the cross braces you added. Before you permanently hang the joists, prop them up from beneath with 2x4 temporary posts to force the tops up to be level with the tops of the existing joists (pushing the flooring above back into shape), then secure them permanently in place with joist hangers.

Add blocking between the old and new joists as well, to ensure the new joists don't warp/twist.

See the pic attached to help clarify what I mean

• Black = OLD work already there
• Red = new cross bridging or bracing
• Blue = new joists
• Green = blocking to prevent warping
• Purple circles = places where you use joist hangers

Blocking typically refers to the structure that prevents the joists from twisting, which would be a concern over a load bearing beam. A solid piece of wood, often the same material as the joists themselves, is installed perpendicular to the joists without any gaps (e.g. I joists would use a piece of I joist for blocking). Two 2x4's installed in an X could also be done, and I've seen that with engineered joists, but check with your local building codes to be sure it complies.

I could also see blocking refer to additional vertical members (2x4's) to carry the load from the beam up to another load bearing object above the floor (e.g. a column). The last type of blocking I can think of would be fire blocking to prevent fire from traveling through the ceiling between parts of the home, though it's unlikely you'd see this requirement in a single family structure outside of a garage.

Like Tester101 says, call the inspector and ask for clarification, they should be happy to provide it.