Inspecting for beam sag

Exterior · Porches, Decks and Balconies · printed page 332 (PDF page 333)

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Book index entries

Exterior Sag Beam Sag

Text in the illustration

beam
level
column
even with a carpenter's level, it can be difficult to determine if a beam is sagging by looking at it from the side
side view
sighting along the bottom edge of the beam gives a much clearer indication of whether it's sagging
perspective view

Generated explanation

The illustration shows a wood beam supported by two columns on individual bases, in side and perspective views. In the side view, a carpenter's level is held against the underside near midspan, and several framing members extend above the beam. The annotation explains that beam sag can be difficult to detect from the side, even with a level. The perspective view emphasizes the curved bottom edge and illustrates sighting along that edge to better identify sag between supports.