Floor Joist Blocking

Building code requires the use of blocking for floor joists that exceed 2 inches in width by 12 inches in depth.

Floor joist blocking. Engineered i joists can span long distances to make a flat and solid subfloor. Blocking provides the floor joists with lateral support and it provides a way to transfer shear and vertical loads from the walls above to the foundation below. Making professional blocks to make the blocks i cut sections of i joist 1 inches smaller than the space between the joists. Tradeready blocking is pre cut and formed to fit securely between the floor joists to prevent joist rotation.

Section r502 7 of the 2009 international residential code specifies that joists must be laterally supported by solid blocking that s not less than 2 inches thick and the full depth of the joist. Floor joist blocking the irc requires mid span blocking for joists with a width to depth ratio greater than 1 to 6 which means that even 2x12 s don t need mid span blocking. Long spans of joists in newer homes may wobble or bounce from foot traffic. How to make floor joists stronger.

After several centuries of service floor joists in older homes may sag or crack. Structural blocking is an economical alternative to tension bracing cdtb or flat strapping. Blocking is also needed each time the joist overlaps with a center beam and every eight feet between two joists. Floor joist bridging vs blocking i like laying 1 1 8 super flat easy to pound t g together dropping a 2x6 from a floor above doesn t put a hole in it.

Tying the joists together with blocking makes the floor even stronger and stiffer. So one of the last things that need to be done before sheathing the deck is to fill in with blocking. Since the span is short enough that even 2x8 s would have met the code it would be pointless to put blocking at the mid span of 2x10 s since they are already more than stiff enough.