Floor joist span is the length of an individual joist, from the foundation walls to an interior beam. The spacing between joists is
typically 16”
, but can also be 12”, 20”, and 24”.
What is code for floor joists?
Per the prescriptive tables found in Chapter 5 of the International Residential Code (IRC), the standard floor joist spacing used is
12, 16, 19.2, and 24 inches on center
.
Are 2×6 OK for floor joists?
Residential Designer. According to the IRC 2009 for 16′′ centers, 20 lb. dead load, 40 live. You
can span about 9′ with your 2×6
, if you care.
Can floor joists be 24 inches apart?
In most homes, the common standard is
16 inches
on-center. This means from the center of one joist to the center of the next joist there is a measurement of 16 inches. This spacing can be as much as 24 inches apart if you are using a higher grade (therefore stronger) lumber or if your span is very short.
What size boards are used for floor joists?
Lumber graded as #2
is the most common choice for floor joists and other framing lumber.
How do I find floor joists?
Tap the floor with a hammer and listen for a “thud” sound
. Begin at a corner and tap the subfloor. A hollow sound will indicate space, but a “thud” sound will indicate the presence of a floor joist. Once you locate the first two joists, measure the distance between them to determine how wide they are separated.
Are two 2×6 stronger than a 2×8?
In bending, a joist composed of two 2×6’s (true dimension 1.5 inches x 5.5 inches) are
slightly stronger than a single 2×8
true dimensions 1.5 inches by 7.25 inches.
How do you stiffen a 2×6 floor joist?
Use a
sledgehammer or
a pry bar to force the bottom of the new joist along the mudsill and center support beam of the floor system (or the opposite mudsill on short spans) until it’s flat against the existing joist. Nail the new joist to the existing joist with two rows of 10d to 16d nails spaced 6 in.
How far can 2×6 floor joist span?
The maximum distance a 2×6 can span, according to the 2018 IRC, for a floor joist, is
12′-6”
, ceiling joist 20′-8”, rafter 18′-0”, deck board 24”, deck joist 9′-11”, deck beam 8′-3”, and 6′-1” as for header. Always check the codes for determining factors or consult a Structural Engineer.
Do I need noggins in floor joists?
If the span of your joists is
less than 2.5m then you don’t need to include any noggins
. Up to 4.5m span one row of noggins at mid span is needed. Above 4.5m span use two rows of noggins at third points. Noggins need to be at least 38mm wide and the depth should be at least 0.75 times depth of joists.
Should floor joists be 16 or 24 on Center?
The vast majority of floor joist systems are built with
16′′ OC (on center) spacing
. It is possible to build with wider spacing. While 3/4′′ material on 24′′ OC joists may be “to code” in your area, I think that you will find such construction to be noisy and springy.
How far apart are wall joists?
You may wonder, how far apart are studs in my home? They’re always spaced
either 16 or 24 inches on-center
(measured from center to center) along the wall and run between the floor and ceiling. Drywall or lath (for plaster walls) attaches to the edge of the studs.
What is the best size for floor joists?
A floor joist can span nearly 26′ in the most extreme cases. A select douglas fir
2×12
supporting a 30 psf live load and 10 psf dead load, spaced at 12” will have the greatest span length.
How far can a 2×6 floor joist span without support?
2-grade 2×6 joists can span up to
10 feet 9 inches
from beam to beam when spaced the standard 16 inches apart with a maximum live load of 30 inches per square foot. In comparison, No. -1 grade lumber can span slightly further to 10 feet 11 inches under the same parameters.
What wood is used for floor joists?
Wood Species
The common types of wood used to make floor joists are
redwood, hemlock, Douglas fir, and southern yellow pine
. However, not every type of wood product is available across the country. It’s important to understand the strength differences between wood types when choosing joist material.
Do all floor joists run the same direction?
An important thing to know about joists is that
they usually run in the same direction throughout a house
. If the visible joists in a basement or attic run east to west, for example, you can be fairly certain the invisible joists under the bedroom floor also run east to west.
