What is the standard size of a floor joist?

Floor joists range from 2×8 to 2×12. It is less common to see joists that are 2×6, even though they are included in joist span tables. Older homes are more likely to use 2×6 for joist framing.

What size are most floor joists?

Floor joists are generally 6, 8, 10, or 12 inches in width, with 8 or 10 inches as the most common sizes. Floor joists come in dimensional lumber lengths from 8 to 16 feet or more.

What size should joists be?

Commonly used joist sizes are 2-by-6, 2-by-8 and 2-by-10. For example, when you space joists 16″ apart — which is standard for residential decks — a deck spanning 9 1/2′ would require 2-by-6 joists, a 13′ deck would need 2-by-8 joists and a 16′ deck calls for 2-by-10 joists.

How many joists is 12 feet?

A 12-foot long deck with joists 16 inches on center will require 10 joists.

What size floor joist is needed for a 12 foot span?

Thus you will need a 2×6 (2-by-6) size of floor joists for 12 foot span at standard 12 inches spaced.

Can you use 4×2 for floor joists?

Yes 14″ spacing between the the joists. The joists run across the house = 25 ft. Shortest unsupported distance to dwarf wall = 4 feet.

Are 2×8 OK for floor joists?

The span for a 2×8 floor joist can range from 7′ 1” to 16′ 6”. In addition, floor and deck joists have to support a fairly high live load because they provide support underneath living areas. You may find that a 2×8 does not offer the necessary support on its own.

What size floor joist do I need for a 16 foot span?

Max. Live Load 60 lbs/ft2 (2873 N/m2)

Maximum Span (ft – in)
Nominal Size (inches)	Joist Spacing Center to Center (inches)	Lumber Grade
2 x 8	24	9′ – 4″
2 x 10	12	16′ – 1″
16	13′ – 11″