Floor Framing Overview

  • Floor joists should overlap above intermediate supports a minimum of 12 inches and a maximum of 24 inches.
  • Floor joists should have some type of anti-rotational device installed. In older homes, this was typically 1x4 X bracing installed approximately midspan. In newer homes it typically consists of blocks installed above supporting walls and beams.
  • Floor joists and girders should have a minimum of 1.5 inches of bearing on wood and steel and 3 inches of bearing on concrete or masonry.
  • Beam pockets in concrete and masonry walls should have a minimum of ½ inch air space on the sides of girders.
  • Bottom plates of walls should be anchored to the tops of foundation walls.
  • Look for signs of leakage and decay beneath sliding glass exterior doors, toilets, tubs, and sinks on the floor above.
  • Look for the use of minimum 10d hanger nails (not 8d).The number should be marked on the head.
  • Look for cut or damaged floor joists.
  • Look for improperly notched or bored floor joists.

Main Floor Structure

  • Floor joists, sheathing and support structure:
    • Design/material/installation quality;
    • Damage, deterioration, decay;
  • Look for decay beneath exterior door thresholds and plumbing fixtures.
Framing Fasteners
  • Metal connectors and their fasteners;
    • Fasteners for almost all single metal connectors will be minimum 10d with the number marked on the nail head;
    • Fasteners for almost all double and triple metal connectors will be minimum 16d vinyl-coated checker head nails;
  • Simpson Strong-Tie page on fasteners for connectors.
Minimum Bearing
  • On wood or metal: 1.5 inches
  • On masonry: 3 inches

Allowable Notching and Boring

JOISTS   R502.8.1
  • Notches at the ends of joists cannot exceed 1/4 of the joist depth.
  • Notches in top or bttm cannot exceed 1/6 the joist depth, and cannot be in middle 1/3 of joist
  • Notches may not be located in middle 1/3 of span.
  • Holes may not be located within 2" of the top or bottom and cannot exceed 1/3 the joist depth.

STUDS   R602.6


  • Cutting or notching up to 40% of stud width is permitted.
  • Boring holes up to 60% of stud width is permitted (also for a single, doubled- [sistered-] stud assembly).


  • Bored holes cannot be closer than 5/8" to the edge of a stud.
  • Any stud may be cut to a maximum of 25% (1/4) of its width.
  • In exterior and/or load-bearing walls, holes cannot be bored a diameter greater than 40% of stud width.
  • Top plates cut, drilled, or notched by more than 50% of their width must have a galvanized steel tie installed across the break/opening measuring minimum .054" x 1.5", fastened with at least 8- 16d nails each side of the break/opening.
  • Bored holes in studs must not be located in the same as cuts or notches.
  • If a hole is 40% to 60% of stud width, the stud must be doubled (sistered). No more than two adjacent studs can be doubled.



Two common reasons for squash blocks are:
  1. To carry load-bearing walls that stack above walls (or beams)
  2. To carry concentrated loads from above through the floor