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How to cut framing blocking fast and square

Blocking goes between floor joists, studs and rafters to stiffen the frame, back up sheathing edges and stop fire from traveling through wall cavities. It is simple carpentry, but cutting dozens of identical blocks is where framing time disappears.

1. Get the block length from the layout, not the tape

On 16″ on-center framing with 1½″ thick members, the block between two joists is 14½″. On 24″ on-center it is 22½″. Measure one real bay to confirm, because joists are not always perfectly on layout.

2. Use the same depth lumber as the joists

Floor joist blocking is usually cut from the same size stock as the joists, such as 2x10 blocking for 2x10 joists, so it sits flush with the top and bottom edges. Wall and fire blocking is usually 2x4 or 2x6 to match the studs.

3. Set up for repeat cuts

The slow part is not the cut. It is pulling the tape, marking and squaring each block. A stop block on a miter saw works at the bench, but it is not always set up where you are framing. A circular saw jig such as the CutBoss combines a locking length stop with a saw fence, so you hook the board, cut along the fence, and every block from 6″ to 36″ matches without marking.

4. Cut a few extra

Knots, splits and wane will cost you a block or two. Cutting a few extra keeps you from walking back to the saw.

5. Install in a staggered line

Snap a line across the joists, then stagger the blocks on either side of it so you can face-nail through the joist into each end. Check local code for required blocking locations and fastening schedules.