Question 1

How far can a 2x10 floor joist span?

Accepted Answer

A #2 SYP 2x10 at 16" OC can span up to 18'0" for a 40psf floor load. At 12" OC it reaches 19'10". Species, grade, and spacing all affect maximum span.

Question 2

What size beam do I need?

Accepted Answer

Beam size depends on span length, tributary width, and load. For a 12ft span supporting a 12ft tributary width at 50psf total load, you might need a doubled 2x12, 3.5x11.875 LVL, or equivalent.

Question 3

What is the difference between LVL and glulam?

Accepted Answer

LVL (laminated veneer lumber) has higher bending strength and is narrower. Glulam is wider and often used for exposed beams. Both are engineered and stronger than solid lumber.

Question 4

How do I read span tables?

Accepted Answer

Find your species and grade, then look up your joist size and spacing. The table shows maximum clear span in feet-inches format (e.g., 18-0 means 18 feet 0 inches).

Joist Size	12" OC	16" OC	24" OC
2x6	11-10	10-9	9-5
2x8	15-7	14-2	12-4
2x10	19-10	18-0	15-9
2x12	24-2	21-11	19-1

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Full Span Table — SYP #2 (40psf floor)

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