Floor Joist Under Load Bearing Wall

Makes the plumbers and electricians smile.

Floor joist under load bearing wall.

Generally when the wall in question runs parallel to the floor joists above it is not a load bearing wall but if the wall runs perpendicular at a 90 degree angle to the joists there is a good chance that it is load bearing. However the floor joists must also be adequate to support the additional load from the wall. But larger is not always better when builders are constructing a home or adding a room addition. I see the doubled fj s under bearing walls with and with out a space between to allow plumbing sometimes.

This meant cutting a hole in the joists and installing a trimmer joist 1 on. But in the past it had been necessary to install a staircase to these rooms above. Common sense tells you that large floor joists can carry more load and spacing joists closer together also increases the load bearing capacity of a floor. The living room dining room is open concept and the kitchen is walled off.

However there is a large double 2x10 header above the entry way see picture 4 in this wall supported by a jack stud on either end see picture 5. The joists span across a room or other area are supported on their ends and sometimes in their middles by load bearing walls or beams. The extra two inches of vertical distance when a floor is framed with 2 x 10 joists rather than 2 x 12s can be quite important for example. After incomplete advise by a contractor on how to tell if a wall is load bearing i started tearing out all of the plaster walls realized the wall is load bearing.

Therefore joists may run from wall to wall wall to beam or beam to beam depending on the size of the area they span and the structural design of the home. The space i am opening is a little under 8. But for nonbearing walls why do any extra joists at all. Load bearing walls and floor joist spans how not to knock down a load bearing wall.

Is the wall parallel or perpendicular to joists. Thus for a 2x4 bearing wall two joists are below spaced 3 1 2 apart directly under. For better performance the designer may wish to add a joist or blocking panels below the non bearing wall. Score 1 for being load bearing.

When doubled fj s are under a non load bearing wall to eliminate the floor flex that creates a drywall crack above a door header on the wall above typically between a bedroom and master bath. Nonetheless this does not ensure good floor performance. This would not be strong enough under normal construction methods to hold the floor above. Score 1 for being non load bearing.