Strengthen Attic Floor Joists

Plywood firmly fastened to the undersides of joists helps prevent this side to side bending and stiffens the floor.

Strengthen attic floor joists.

You will have to use a very sturdy piece of wood or some steel plating to reinforce the floor joists. Strengthening attic joists for live loads by sistering if the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. Jacking them up too fast may cause cracks in the walls and floors overhead. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.

Sistering is the process of adding a new joist next to each existing joist. Pretty sure you mean joists not rafters rafters are the sloped members that run directly under your roof whereas joists are the horizontal members that sit atop the ceiling of the floor below the attic. Now it is time to use some wood and screw it into place on the original joist as well as the cross beam. In my 80 year old house the attic had 2x6 floor joists about 16 oc.

For this fix to work well the upper edges of the joists must be solidly fastened to the subfloor above. Where they connect to both the top and bottom joists each gusset pair will transfer approximately 100 pounds that s 50 psf of floor load times the 3 foot gusset spacing times the 16 inch joist spacing divided by the two joists. This is a great answer. Adding a 2 x 4 along the bottom chord of the 2 x 6 ceiling floor joist maybe helpful in stiffening the joist as well.

A layer of 3 4 in. A steel plate can be used the same way. Gluing and screwing a 3 4 attic subfloor and providing solid bridging should also be considered. I went to get a permit from the city to finish the attic and they said i needed to reinforce the floor since for a live load it was not strong enough for our span below about 12.

They create the structural strength of the attic floor. A day until they re level. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Tack a beam under the sagging joists.

Squeaks in a floor usually mean that the subfloor has loosened from the joists.