Contents

- 1 What size are floor joists in residential construction?
- 2 What size should floor joists be?
- 3 Can I use 4×2 for floor joists?
- 4 What size wood is used for floor joists?
- 5 How far can a 2×6 floor joist span without support?
- 6 Can I use 2×6 for floor joists?
- 7 What is the maximum span of a 2×6 floor joist?
- 8 How far can a floor joist span without support?
- 9 How much weight can a 2×6 floor joist hold?
- 10 Do I need noggins in floor joists?
- 11 How much weight can a joist hold?
- 12 How do you calculate floor joists?
- 13 How far can a 2×8 floor joist span without support?
- 14 What is code for floor joist?
- 15 What size beam do I need for a 20 span?

## What size are floor joists in residential construction?

Looking at this table you will see there is a choice in the size of floor joist (**2 X 6**, **2 X 8**, **2 X 10** or **2 X 12**) and there is a choice in the joist spacing (12″, 16″ or 14″). The floor joist spacing is the distance between the centers of any two installed joists.

## What size should floor joists be?

A. Carl Hagstrom responds: The rule of thumb that I like to use when sizing uniformly loaded residential **floor joists** is “half the span plus two.” First, round the clear span of the **floor joist** up to the nearest foot, and divide by two. Then add two to the answer.

## Can I use 4×2 for floor joists?

**4×2** timber **floor joists** on the ground **floor** have been **used** for decades but **should** be no more than 16 inch or 400 mm centres and be supported at no more than 2 metre centres, 6ft or 1.8 m is preferable and practical.

## What size wood is used for floor joists?

**Lumber** graded as #2 is the most common choice for **floor joists** and other framing **lumber**. It has more knots and defects than higher grades, but usually not enough to cause significant loss of bending strength.

## How far can a 2×6 floor joist span without support?

How **far can a 2×6 Rafter span without support**? The table states that 2 X 6 rafters spaced 16 inches on center (o.c) **can span** a **maximum distance** of 13 feet 5 inches.

## Can I use 2×6 for floor joists?

How **do** I keep them even? In general terms, **joists** spaced 16 inches on center **can** span 1.5 times in feet their depth in inches. A 2×8 up to 12 feet; 2×10 to 15 feet and 2×12 to 18 feet. **2×6 joists should** only be **used** on ground-level decks that **do** not require, and will not provide for, any guards.

## What is the maximum span of a 2×6 floor joist?

Max. Live Load 30 lbs/ft2 (1436 N/m2)

Maximum Span (ft – in) |
||
---|---|---|

Nominal Size (inches) | Joist Spacing Center to Center (inches) |
Lumber Grade |

2 x 6 | 12 | 12′ – 6′” |

16 | 11′ – 4″ | |

24 | 9′ – 11″ |

## How far can a floor joist span without support?

Douglas fir 2-by-10 joists graded as “Structural Select” allows joist spans up to 21 **feet** for a live load of 30 pounds per square foot when spaced 12 **inches** apart, 19 **feet** 1 inch for 16 inch spacing and 16 **feet** 8 **inches** for 24 inch spacing.

## How much weight can a 2×6 floor joist hold?

To give you a general idea though, floor joists are sized to support **40 pounds** per square foot of “live” load (moving weight) or 10 psf “dead” (stationary) load.

## 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**.

## How much weight can a joist hold?

A uniform load rating on a beam can easily be translated into what an equivalent maximum point load can be. For example, a floor joist at 16” spacing’s that can carry **53 pounds** per linear foot would translate into a 318 pound single point load at its center.

## How do you calculate floor joists?

The basic math is to divide the width by the on center spacing, round up to the nearest integer and then add one for the first **joist** (at the zero position). The length is used for the length of the **joists** or I-**joists**.

## How far can a 2×8 floor joist span without support?

In general terms, joists spaced 16 inches on center can span 1.5 times in **feet** their depth in inches. A 2×8 up to 12 **feet**; 2×10 to 15 **feet** and 2×12 to 18 **feet**.

## What is code for floor joist?

Floor Joist Building Code Requirements

The joist must have a minimum of 1 1/2″ riding on the wall or beam. If the joists are lapped, then they must be lapped at least 3″. Maximum end notches for **2 x 8**, **2 x 10**, and **2 x 12** respectively are 1 13/16″, 2 5/16″, and 2 13/16″.

## What size beam do I need for a 20 span?

you looking around 4×14, 4x 16 for a **20**‘ **span**. i **would** use a glue lam and not a solid **beam** ( 1 pc ). steel **would** be best for strength and space.