Roof Joist Fixing

Identify the cracked or sagging joist before it causes additional problems.

Roof joist fixing.

Birdsmouth joints cut into roofing rafters and mounted in place on top of the wall plate. Cut a sister joist the same length as the damaged joist. Tack a beam under the sagging joists. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.

Keep in mind that the joist extends through the wall. If is wasn t for this joint a rafter or roofing joist would only balance on top of the wall plate making fixing difficult not to mention the fact that there wouldn t be any solid connection between the roof and the supporting walls below. If the problem worsens it can cause the ceiling or upper floor to sag crack the drywall covering on the ceiling and compromise the structural integrity of your home. How to repair a cracked or sagging joist.

Set out the ceiling joists onto the wall plates the ceiling joists are installed before the rafters as they will stop the roof spreading and also give something for you to lay planks across to stand on when building the roof. Jacking them up too fast may cause cracks in the walls and floors overhead. To fix the joists and rafters down on to the wall plates they should be toe or skew nailed to the top plate like below. Squeeze the joist hanger tightly around the joist and drive the speed prongs into the ledger board to temporarily hold the joist in place.

Usually when a joist gets sistered the new lumber does not span the entire length of the old joist. However doing this does not fix the slant that the floor has taken since the old joists got damaged. To replace the joist you need to measure the entire length. Place a level on the bottom edge of the joist to determine the amount of sagging that has occurred.

A damaged broken or cracked ceiling joist can cause a ceiling to sag and should be repaired as soon as possible. Repair and reinforce a ceiling joist by affixing a new plank to the side of the joist. A day until they re level. Make sure the joist is sitting squarely in the joist hanger without gaps alongside and under the joist.

Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Total costs will depend on the extent of the damage and the ease of access to the joists through a basement or crawlspace but in general sistering averages 100 300 or more per joist and could run 1 000 3 000 or more to repair a tilted wavy or bouncy floor under an average room. However replacing the entire joist gives the home much better structural integrity.