Improper Bridging Between Floor Joists

Adding two rows of bridging costs a few dollars per joist.

Improper bridging between floor joists.

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. To install the type shown here drive the toothed end into the joist and nail the other end. Install with two 6d common nails per end. Solid blocking and metal or wood x type bridging do accomplish the same task.

Floor joist bridging is critical to the structural strength of a floor as shown in figure 1. Building code requires the use of blocking for floor joists that exceed 2 inches in width by 12 inches in depth. The blocking or bridging between joists or rafters also contributes to this phenomenon. How to make floor joists stronger.

Proper bridging distributes the load on the floor to other joists and over time prevents floors from sagging and squeaking do to floor joists twisting and warping. Yet it is not uncommon to find bridging not properly installed or missing all together. After several centuries of service floor joists in older homes may sag or crack. Simpson strong tie tension bridging galvanized steel the ltb s are used in floor systems to resist the overturning of floor joists and features a staggered nail pattern.

From both ends of the span. Long spans of joists in newer homes may wobble or bounce from foot traffic. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. But larger is not always better when builders are constructing a home or adding a room addition.

Blocking is also needed each time the joist overlaps with a center beam and every eight feet between two joists. The joists shown here for example span 12 ft so we added rows of bridging 4 ft. Mike installs galvanized steel briding in between the floor joists on this bedroom addition project in rocky hill ct. From a structural perspective you are correct.

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 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.