The span rule of thumb for glued laminated timber (glulam) depends on various factors such as the species of wood, load requirements, and design considerations.

Glulam is glued laminated timber, also abbreviated as glulam, is a type of structural engineered wood timber product constituted by layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives. In US, the material made of wood providing the laminations is termed laminating stock.

By laminating a number of smaller pieces of glulam lumber, a single large, strong, structural member is manufactured from smaller pieces. These structural members are used as vertical columns, horizontal beams, and arches, header, girder, rafter, purlin and ridge beam in wood frame house.

Glulam optimizes the structural values of wood. Because of their composition, large glulam members can be manufactured from a variety of smaller trees harvested from second-growth forests and plantations.

**Glulam beam**

Glulam beam is engineered wood products manufactured by through the union of individual smaller pieces of lumber with special types of industrial adhesives usually Melamine or Polyurethane resin adhesives. Its construction offers superior strength and stiffness over dimensional lumber. This type of beams is highly durable and moisture resistant, capable of generating large pieces and unique shapes.

**Glulam beam size calculator**

To calculate the size of Glulam beam, convert the span length in feet to inches by multiplying with 12, divide the total span length in inches by 20 to get depth of Glulam beam. Width is 1/3 to 1/4 of the depth of Glulam beam.

Formula to calculate Depth of the Glulam beam = Span in inches/ 20. Width of the Glulam beam = Depth of beam/ 3. For example: if span is 20 feet, then depth of glulam beam = (20 × 12)/20 = 12″, and width = 12/3 = 4″. So, you would need 5-1/4″ × 12″ size of glulam beam to span 20 feet.

**Glulam beam span calculator**

To calculate the span length of Glulam beam, multiply the depth of beam in inches by 20 to get total span length in inches, divide the span length in inches by 12, resulting figure is span of glulam beam in feet.

Formula to calculate span length of glulam beam in feet = (Depth of beam in inches × 20)/ 12. For example: how far can you span 5-1/2″ × 16″ size of glulam beam, span of glulam beam = (16″ × 20) / 12 = 320/ 12 = 27 feet. So, 5-1/2″ × 16″ size of glulam beam can allow to span 27 feet approx.

**Glulam beam sizes**

Typically, the size of Glulam beam is represented by their width and depth. Depth of Glulam beam are range from 7 1/4 inches (184mm) to 23 7/8 inches (606mm). Width of Glulam beam are range from 3-1/8″, 3-1/2″, 5-1/8″, 5-1/2″, 6-3/4 inches and 7 inches.

Glulam beam depth are typically are 7 1/4 inches (184mm), 9 inches, 9 1/4 inches (235mm), 9 1/2 inches (241mm), 11 1/4 inches (286mm), 11 7/8 inches (302mm), 14 inches (356mm), 16 inches (406mm), 18 inches (457mm), 18 3/4 inches (476mm), 20 inches (508mm) and 23 7/8 inches (606mm).

Typical stock beam widths used in residential construction include :- 3-1/8, 3-1/2, 5-1/8, 5-1/2, 6-3/4 inches and 7 inches. For non-residential applications, where long spans, unusually heavy loads, or other circumstances control design, custom members are typically specified.

In this article we know about Glulam span rule of thumb for calculating size (width and depth) of Glulam beam, Glulam girders and Glulam Column or post for the construction of wooden frame house that will help you in better understanding and to figure out or estimate of Glulam beam, girder and column size and their depth and help in important for you to use the right size.

**Glulam span rule of thumb for beam, girder and column**

By laminating a number of smaller pieces of glulam lumber, a single large, strong, structural member is manufactured from smaller pieces. These structural members are used as vertical columns, horizontal beams, and arches, header, girder, rafter, purlin and ridge beam in wood frame house.

**Here’s Glulam span rule of thumb for beams, girder & column:-**

1. The span rule of thumb for glulam beams is typically about 20 feet span per foot depth, depending on factors like load, species, and grade.

2. The span rule of thumb for glulam girder, the depth of the Glulam girder is 1/20th of span in inches + 6″.

3. In general, a typical 6×6 Glulam column or post can carry approx 600 sq ft of roof, a 8×8 Glulam column for 1000 sq ft, a 10×10 Glulam column for 2000 sq ft, and a 12×12 Glulam column for 3000 sq ft.

**Thumb rule for Glulam beam**

As per glulam span rule of thumb the depth of the Glulam beam is 1/20th of span in inches and their width is 1/3 to 1/4 of the depth. If beam spanning is 20 feet in length, then their depth = (20 × 12) ÷ 20 = 12 inches and width is 12/3 = 4″. So, you would need 5 1/2″ × 11 7/8″ size of Glulam beam for 20 foot span.

**Thumb rule for Glulam girders**

As per thumb rule & general guideline, the depth of the Glulam girder is 1/20th of span in inches + 6″ and their width is 1/3 to 1/4 of the depth. If girder spanning is 20 feet in length, then their depth = (12 × 12) ÷ 20 = 12 inches, add 6″ extra, then overall depth 12+6 = 18 inches and width is 18/3 = 6″. So you would need 5 1/2″ × 18 size of Glulam Girder for a 20 foot span.

**Thumb rule for Glulam column**

As per thumb rule & general guideline, a typical 6×6 Glulam column or post can carry approx 600 sq ft of roof and floor area, while a 8×8 Glulam column can carry approx 1000 sq ft. Likewise, a 10×10 Glulam column can carry approx 2000 sq ft, while a 12×12 Glulam column can carry approx 3000 sq ft. In addition a 14×14 Glulam column can carry approx 4000 sq ft of roof and floor area. Column are usually in square cross – sections.

**Conclusions**:-

As per thumb rule & general guideline, depth of the Glulam beam is 1/20th of span in inches and their width is 1/3 to 1/4 of the depth. Depth of the Glulam girder is 1/20th of span in inches + 6″ and 6×6 Glulam column can carry approx 600 sq ft of roof and floor area.