Doubling Up Every Other Floor Joise

Jacking them up too fast may cause cracks in the walls and floors overhead.

Doubling up every other floor joise.

The main reason for doubling up floor joists is to double the strength of a single floor joist. To achieve this doubling effect in strength and stiffness you will indeed need to gusset the upper and lower joists together. I don t think doubling up a 16 2x8 will all of a sudden span 30. I would think the doubled up s would span further because you can attach one to the other more thoroughly.

If you double those joists you can span 12 feet 3 inches. Cut a piece of 2 by 6 or 2 by 8 lumber according to the width. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Not even a 12 micro will span that far.

A day until they re level. Nail the block in place with 16d. Measure the width between the span of two joists. So instead of having a post run all the way from the roof to the ground it can stop at the double floor joist.

Create space by doubling joists if you need to remove part of a joist double the joists to each side then add doubled joists between them to carry the load of the severed joist. Use joist hangers for all connections. Tack a beam under the sagging joists. For example a joist made from doubled 2 x 6s can span a distance about 25 percent more than a single 2 x 6 but a 2 x 12 can span about 80 percent more than a 2 x 6 even though it has the same amount of wood as a doubled 2 x 6.

Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. If we use strong enough gussets and fasteners we know that the top and bottom joists will deflect by exactly the same amount when loaded. This allows you to install a supporting post off the double floor joist to hold a second storey or a roof beam.