Wendrick Truss Calculator (2024)

FAQs

How do I calculate how many trusses I need? ›

Truss count = ((roof length * 12) / 24) + 1

The simplest form of this equation is to take the length of your roof and divide it by 2. For example, if your roof is 40-feet long, it will need a total of 20 trusses.

The formula is truss count = ((roof length × 12)/24) + 1 . This equation will help you determine how many trusses your roof needs. For example, if your roof is 30 feet long, you will need 16 trusses.

For example, your house is 40 feet long with a 24″ rafter spacing. So the first thing you need to do is convert 30 ft to inches. 40ft x 12″ = 480″ (length in inches) ÷ 24″ on-center = 20 rafters. After getting the answer, add 1 for the '0' rafter and multiply it by 2.

A formula is now applied to the truss to calculate load strength. The formula, which can be written as M+3=2*N, says that the number of members of a truss plus 3 must equal twice the number of nodes. When both sides of this equation are equal, the roof is stable and can support stressful loads.

For an example home that is 30 feet long, the number of trusses you will need with 24 inch spacing is (30*12)/24 = 15, plus the 1 extra to make 16 roof trusses in total.

Typical spacing is 16 or 24″ between trusses, BUT- this is an engineered determination.

Trusses offer a new way of building a roof, and are less expensive than rafters. Rafters are built on-site, while trusses are pre-fabricated. Trusses are considered stronger, but offer less flexibility for remodeling.

Larger joists can span across wider areas. For example, a 2x6 joist would have a 12-foot, 6-inch maximum span, and a 2x10 joist would have a 21-foot maximum span. Additionally, wood species and grading determines how far apart floor joists can be spaced.

How to calculate truss height? ›

An approximate height of a pitched truss can be calculated with the following formula: take 1/2 the span and multiple it by the pitch. Then add about 4 in. for the top chord lumber. For example: a 33-9-0 (33 ft., 9 in.

Method of joint: This method involves isolating each joint of the truss and considering the equilibrium of the joint when determining the member axial force. Two equations used in determining the member axial forces are ΣFX=0 and ΣFy=0.

The load-bearing capacity of a truss or rafter depends on several factors, including the material used, its dimensions, and the design of the structure. Generally, the load-bearing capacity is determined by the maximum load the truss or rafter can support without experiencing excessive deflection or failure.

Building width not greater than 60 feet perpendicular to the truss span. Truss span not greater than 36 feet.

The spacing really depends on the individual project and specifications. Trusses are often spaced anywhere from 4 feet apart to even 12 or 16 feet apart.

An approximate height of a pitched truss can be calculated with the following formula: take 1/2 the span and multiple it by the pitch. Then add about 4 in. for the top chord lumber. For example: a 33-9-0 (33 ft., 9 in.