Sistering Ceiling Joists

In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together side by side.

Sistering ceiling joists. Sister or double the ceiling joists with 2x6 s or 2x8 s with the ends resting on the wall top plates then lay the subfloor on the new joists. Doing so strengthens weak joists and can help straighten sagging joists. Here s how we are correcting the problems.

Stacking joists is not nearly as stable as sistering which braces the joists against twisting. Reinforce the joists and lay down a wood subfloor osb ply etc so i m not tiptoeing on joists whenever i m up there. Not so with stacked joists.

Framing lumber is the typical choice for sistering. If there was water damage make sure that whatever leaky pipe or condensation issue caused the rot is fixed. I forgot to mention the construction adhesive in between them.

The most common way joists are repaired is to sister it up. Our 60 year old floor joists are showing their age. The sag could be reduced or eliminated by installing king posts or leom could sister 2x8s to the 2 6 joists to roughly triple the load bearing capacity of the ceiling.

These problems must be addressed firsthand prior to implementing any restoration steps. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Blocking solves the problem.

Sistering is the process of adding a new joist next to each existing joist. Think of it like this. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.