How Far Apart Should Floor Joists Be?

In most woodworking projects, joists are used extensively. If you’re laying a hardwood floor, you’ll almost likely need to install joists for extra support. You can be confused by joist spacing when laying the floor.

The joist spacing might be a little confusing at times. However, there are several common guidelines to follow. Take a look at the information below to learn more about floor joint spacing.

How far apart should floor joists be?

Floor joists may be spaced at 12-in, 16-in, or 24-in intervals in the United States, depending on the construction. However, the most typical joist spacing is 16 inches. This gap is normal since it can sustain the load capacity found in most homes. Some people use 19.2-inch spacing, but it’s not very common.

Floor joists are normally used to add extra support to the floor framework. This helps keep the structure strong and the flooring from twisting or wrapping.

Building codes say that the most common spacing between floor joists within the United States is 16 inches, and that’s what most people do. Some people, however, construct with 12-in and 24-in spacing.

The majority of wood flooring employs floor joists. The spacings of these joists, however, vary depending on the style of structure. The following section provides the necessary floor joist spacing for various constructions:

In a residence:

The building code in the United States allows for three distinct spacings for floor joints. There are three sizes available: 12-in, 16-in, as well as 24-in. The 16-inch gap is, nevertheless, the most typical spacing.

On a deck:

The joist spacing for deck flooring is comparable to home measurement. The 12-in and 16-in gaps are the most typical spacing on decks.

For a shed:

Shed joist spacing is typically 16 inches. A 24-in gap, on the other hand, is desirable if you want to enhance load-bearing capability.

In a mobile house:

Mobile houses have 12-in, 16-in, as well as 24-in floor joist spacing, much as traditional homes. However, the normal spacing for such a purpose is 16 inches.

Engineered floor joists span:

The manufactured floor joist spans typically have a 16-inch space between them. Gaps of 12 inches, 20 inches, and 24 inches are also acceptable.

What is the maximum span of these floor joists?

Most often, the term “joist span” refers to the length or measurement of the space that a joist covers between two beams or another supporting structure. The spans are an important measurement in any construction project.

To obtain the required spans for the joists, most carpenters utilize pre-calculated measurement tables.

The span of joists is determined by a variety of factors. The kind of wood, lumber grade, the center spacing between the joists, the weight, and the joists’ size are all elements to consider. The section outlines possible spans for joists of various sizes and types of wood.

The o.c. here is the normal 16-in, and the wood quality is grade 2.


2-in x 4-in joists may be a little odd when it refers to floor joists. There are, however, pre-calculated figures for this joist size. The span for Yellow Pine would be 6-ft 4-in, whereas the span for Douglas Fir will be 6-ft 2-in.


The span lengths varied in 2-in x 6-in joists. Yellow Pine joists have a span of 9 ft 4 in, whereas Douglas Fir joists have a span of 9 ft 11 in. This length is about 9-ft 2-in for Spruce.


The 2-in x 8-in joists are somewhat larger. That’s why their spans are a little longer in general. This size Yellow Pine joist spans roughly 12-ft 3-in. When compared to this, a 13-foot-1-inch Douglas Fir is more appropriate.


Compared to the preceding sizes, 2-in x 10-in joists may span a lot more. Yellow Pinewood has a span of around 15 feet and 8 inches, whereas Douglas Fir has a span of 16 feet and 9 inches.


The largest joists used for flooring are 2-in by 12-in joists. Yellow Pine joists are 19 feet 1 inch wide, whereas Douglas Fir joists are 20 feet 4 inches wide.

What is the maximum distance that floor joists may be without support?

When constructing a wooden floor, floor joists have become an important component. And determining the proper number of joists as well as their spacing is a challenging process. It might perhaps be more difficult than it seems.

Several elements must be considered when determining how long your floor joists could last without support. It’s important to think about things like characteristics of wood, grade of wood products, width and thickness of joists, spacing between joists, and the amount of weight that is expected to be put on them.

As a result, it’s acceptable to claim that there isn’t a precise answer to this topic. However, a typical principle is to add 1 meter of additional width for every 1.5 times the board’s depth in feet. However, depending on the kind and quality of wood used, these figures may vary.

What is the minimum number of floor joists required?

Joists are often used to offer extra support and structural solidity to timber flooring.

The number of joists needed for a floor, on the other hand, is determined by the size of the foundation, the weight it will sustain, and the spacing between each joist.

Finding the necessary quantity of joists is more difficult than many people believe.

When the normal spacing between floor joists is 16 inches, the number of floor joists required for a conventional 11-foot by 12-foot room will be roughly 12. Other elements, such as the kind of wood used and its quality, have an impact on this figure.

You may use basic math to get the precise number of joists you’ll need. Subtract the width of the floor from the floor’s center spacing. After that, you rounded the value to the closest integer. This is the number of joists you’ll need for your floor.

Is it necessary to install noggins in the floor joists?

The purpose of noggins is to give your wooden construction some more stability. As a result, adding noggins to your floor joists is always a good idea. As a result, your floor will be more solid and durable.

Check the joist spans to see whether noggins are required or not. No noggins are required for joists with something like a span of 2.5 meters. When the joists span roughly 4.5m, 1 row of noggins will be required mostly on middle spans.

For each third point on joists with spans more than 4.5m, 2 rows of noggins are required. Noggins on your floor joists are beneficial, as previously stated.

If you’re on a budget, though, you may ignore them or reduce their numbers to the bare minimum.

Do joists benefit from noggins?

Noggins are important wooden supports that help to keep the joists in place. Because they offer structural balance and strength, they are often employed in floor and wall joists.

Bridging is another term for noggins. The main purpose of joists or studs on such a hardwood floor surface is to provide support. They may also be used to secure independent structures of a basic framework.

Noggins provide additional support while also hardening the timber. As a consequence, the whole structure becomes more rigid and less vulnerable to future bending.

Noggins are important in the construction of walls because they assist to keep the joints from breaking. Overall, it’s reasonable to claim that noggins help to strengthen joints.

Is it necessary to brace or cross brace floor joists?

The floor joists’ role is to give extra support plus load-bearing capability. They’re horizontally positioned wooden reinforcements for the floor’s structure. Joists are often positioned in varied patterns to provide additional support.

Cross bracing strengthens joists and offers additional support. Floor joists should have cross bracing, according to the residential construction code.

The floor joists become stronger and stiffer as a result of cross-bracing, which improves the structure’s overall integrity. Unbraced joists, on the other hand, tend to wrap or bend with time. As a result, you’ll need to install cross bracing in your floor joists.

The use of cross-bracing on floor joists is required in several jurisdictions. If you’re constructing a new house, be sure to verify your state’s construction codes and, if possible, cross brace your floor joists.


In the United States, the standard distance permitted by building rules is 16 inches. In addition, 12-in and 24-in gaps are occasionally employed, based on the scale of the joists as well as the estimated weight on the floor. However, depending on your unique requirements, you may need to adjust these numbers.