Joist Spacing and Blocking 101
Joist Spacing and Blocking
Quick Reference Guide
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It may be necessary to shim, notch, plane, or replace joists due to size variations, 
crowning, reverse crowning, or improperly positioned joists/framing. Be sure to sort 
and exclude any extremely crowned and/or twisted joists/lumber material. 
PROBLEM: High Joist
POTENTIAL SOLUTIONS:
•  Remove and replace
•  Cut fasteners and lower. 
Reattach.
•  Use a power planer or power 
sander 
STEP ONE
Check Your Framing Before Laying the First Board
PROBLEM: Low Joist
POTENTIAL SOLUTIONS:
•  Remove and replace
•  Leave the low joist and apply 
sister joists (sandwich the board 
w/ 2 new joists)
•  Cut fasteners and raise. 
Reattach.










