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Depending on various factors, the maximum span for a 2×8 floor joist is 16′ 6”. The maximum span for roof rafters is 23′ 9”. … Finally, a single deck beam has a maximum span of 5′ 11” and double maxes out at 8′ 9”. However, the maximum is determined by the species and grade of wood, the spacing, the load, and more.

## What size board is used for roof rafters?

Most Common Thickness

For rafters spaced 20 or more inches apart, 1/2- or 5/8-inch plywood is recommended. The most common rafter spacing is 24 inches, and 5/8-inch plywood is recommended for that. It will support roof loads for most situations and is the standard for most roof applications.

## How much weight will a 2×8 support?

The weight that can be supported by a double or triple wood header

Span (feet) | Weight Supported (lb) | |
---|---|---|

2 x 2″ x 6″ | 3 x 2″ x 8″ | |

6 | 1680 | 4690 |

8 | 3990 | |

10 | 3190 |

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

But first, generally, how far can a 2×8 span without support? Depending on various factors, the maximum span for a 2×8 floor joist is 16′ 6”. The maximum span for roof rafters is 23′ 9”. For headers, the maximum span is 11′ 2”.

## How far can a 2×8 span for a roof?

Max. Live Load 20 lbs/ft2 (956 N/m2)

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

Nominal Size (inches) | Rafter Spacing, Center to Center, OC (inches) | Lumber Grade |

2 x 6 | 24 | 13′ |

2 x 8 | 12 | 21′ – 7” |

16 | 19′ – 7” |

## Can a 2×8 span 12 feet?

A rule of thumb is 1.5 times a joist’s depth but in feet when spaced at 16” centers. In general, a 2×8 will span 1.5 x 8, so 12-feet.

## Can I use 2×8 for deck joists?

2×8 for joists will be fine, with 16″ OC. Should use 2×10 for beams but 2×8 will be fine as well. If you are worried you can triple the 2×8 for the beams but double will be sufficient. You should put the beams at 7 and 14 feet out from the house, with the piers you should do 3 per beam with spacing of 1, 7, 13.

## How much does a 2×8 weight per foot?

Lumber Weight Chart

Weight of Dimensional Lumber | ||
---|---|---|

2 x 6 | 1.5 x 5.5 | 2.34 |

2 x 8 | 1.5 inch x 7.25 inch | 3.09 lbs |

2 x 10 | 1.5 x 9.25 | 3.95 |

2 x 12 | 1.5 x 11.25 | 4.80 |

## How long can rafters go without support?

A 2×6 spaced 16 inches apart can span a maximum distance of 13 feet 5 inches when used as a rafter, 10 feet 9 inches when used as a joist, and 6 feet 11 inches when used as a deck beam to support joists with a 6-foot span.

## How far apart should rafters be?

But they do tend to space rafters in one of several industry-standard increments, typically either 12, 16 or 24 inches apart. These spacing intervals are measured “on center,” meaning that the measurement is taken from the center of one rafter’s horizontal surface to the center of the next rafter.

## How far can a 2×10 Rafter span without support?

A 2×10 beam – made up of two 2x10s nailed together – can span up to 11′ without support beneath a deck that is 4′ wide. For a more normal-sized deck, the same beam can span 8′, supporting a deck that is 8′ wide.