# How far can a roof beam span?

## How far can a roof beam span?

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 16 14′ – 11”
24 13′
2 x 8 12 21′ – 7”

### How far can a roof span without support?

Based on building codes, a 2×6 can span anywhere from 2′-1” to 20′-8” depending on the affecting factors. Ceiling joists don’t normally have the same load restrictions, and so can span greater distances.

#### How do you calculate beam span on a roof?

How to Size a Beam to Hold a Porch Roof

1. Determine the load per square foot that the roof must support.
2. Multiply the load per square foot by the total area of the roof.
3. Divide the total load according to how many supporting beams the roof will have.
4. Write down the beam strength formula: Total load in pounds = FBd^2 / 9L.

How far can a 4X8 beam span without support?

Dimensional Lumber Deck Beam Span Chart

Joist Spans
Douglas Fir-Larch, Hem-Fir, Spruce-Pine-Fir, Redwood, Cedars, Ponderosa Pine, Red Pine 4X6 6′-2″
4X8 8′-2″
4X10 9′-8″
4X12 11′-2″

How far can wood I joist span?

Joists are available in several depths and lengths and superior strength allows them to span up to 30 feet (TRIFORCE span tables).

## What size wood beam do I need to span 30 feet?

If you have a 30-foot span, it is important to know just how long a beam you will need for support. There is a good rule of thumb for this: divide your span (in inches) by 20. So, if your span is 30 feet (or 360 inches) you would divide that by 20 to come to 18 feet.

### How do you calculate beam span?

Calculating the span of a beam requires using various factors that you need to first determine for a structure where the beam is being used. Measure the length of the beam with the tape measure and make a note on a piece of paper. Calculate the square footage of the room by multiplying the width of the room by its length.

#### What is the standard spacing of a roof rafter 2×6?

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 . Another option are 2 X 8 rafters spaced 24 inches o.c.

What size rafter do I Need?

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. Roofs with very heavy loads may require 3/4-inch thickness.

Are purlins designed as continuous beams?

The purlins are designed as continuous beams . The purlin type must be the same for the whole structure, but the thickness may vary. One of the purlin flanges is assumed to be supported with the profile sheet.