Cutting Floor Joists

These joists may need reinforcin g to reduce bounciness sagging or excessive deflection in the floor or ceiling.

Cutting floor joists.

To minimize problems with ductwork. Pry the floor joist from the subfloor with the back of your hammer. Start by cutting out a small 1 2 in 2 5 5 1 cm section of the floor joist with a reciprocating saw. It is very easy to over cut the notches and remove the waste in two swift cuts but over cutting the notches in this manner weakens the structural integrity of the replacement lumber.

Make sure not to install joists so they run parallel to and directly under walls where you intend to install ductwork. Sometimes joists are notched at the end where they bear on a wall or sill. Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of. Then set new joists same height as existing ones alongside the old.

Cutting and or removing joists to provide an entry or access can be the most difficult part of the overall project. Framer jim anderson demonstrates solid techniques for cutting floor joists to length quickly and accurately. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. If the cut outs are too large or in the wrong location the joist can be weakened and unable to support the load it was designed for.

In order to maintain the support integrity of the ceiling or floor joist or rafter system it is important that if joists are cut that the load that was bearing on those joists be transferred to a modified support system. If you need to cut through a joist firm up the floor as shown in fig. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. Notches will compromise the strength of the new joists but some notches are acceptable depending on their location.

Brought to you by fine homebuilding magazine and. Structural floor joist repairs. Then use pry bars and your reciprocating saw to pry and cut the floor joist away from the subfloor. This will create a weak spot.

Tack a beam under the sagging joists. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place.