How To Sister Attic Floor Joists

If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists.

How to sister attic floor joists. However doing this does not fix the slant that the floor has taken since the old joists got damaged. Most floor joists are typically spaced 2 by 8s 2 by 10s and 2 by 12s. Sistering is the process of adding a new joist next to each existing joist. When joists spacings are wider they should be deeper as well to limit stress and deflection under the load.

A day until they re level. The existing ceiling joists are 2x6s clear spanning about 11 feet 3 inches. New homes install i beam shaped joists. Rather than sistering in deeper members which would involve moving wiring can i stack new 2x6s on top of the existing ones.

On both sides of the problem area. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. I need to convert an attic to livable space with minimal disruption to first floor habitation. Depending on the existing attic structure a contractor might be able to sister the current joists by attaching new joists of the same dimension beside them.

If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. 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.