Contents

- 1 What size should floor joists be?
- 2 Can I use 4×2 for floor joists?
- 3 What size wood is used for floor joists?
- 4 What is code for floor joist?
- 5 How far can a 2×6 floor joist span without support?
- 6 Are 2×6 OK for floor joists?
- 7 How do you calculate floor joists?
- 8 What is the maximum span of a 2×6 floor joist?
- 9 Do I need noggins in floor joists?
- 10 What size beam do I need for a 20 span?
- 11 What is the depth of a floor joist?
- 12 Do floor joists need to line up with studs?
- 13 Do floor joist have to be treated?

## 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.

## 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″.

## 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.

## Are 2×6 OK 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.

## 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**.

## 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″ |

## 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**.

## 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.

## What is the depth of a floor joist?

The bulk of the **floor’s** thickness comes from the **joists**, which are the horizontal beams that carry the **floor’s** weight. **Joists** in home construction are usually made with 2-by-10 or 2-by-12 lumber, which are 9 1/4 and 11 1/4 inches deep, respectively.

## Do floor joists need to line up with studs?

Alignment of **joists** over **studs** is only required if using single top plate. The **studs** above are supported by the band board.

## Do floor joist have to be treated?

Generally, building codes require pressure-**treated** or naturally durable wood for the following applications: **Joists** or the bottom of structural **floors** without **joists** that **are** within 18″ of exposed soil. Beams or girders closer than 12″ to exposed soil.