Easily calculate how many trusses you need and determine maximum span capacity based on span, room width, and spacing. Save time and plan your construction project smartly!
When building a floor system, using the right number of trusses is crucial for strength, stability, and cost efficiency.
What is a floor truss?
A floor truss is a prefabricated structural component made from wood or metal designed to carry floor loads across a span without needing internal beams.
Calculate Floor Truss
How to Calculate Trusses Needed
Formula:
Trusses Needed=Spacing (inches)Room Width×12+1
Explanation:
- First, multiply room width by 12 to convert it to inches.
- Divide by spacing between trusses.
- Add 1 because you always need one extra truss at the start.
How to Calculate Maximum Span Capacity
Formula:
Maximum Span Capacity=Span×0.9
Example
Suppose:
- Room Width = 20 ft
- Span = 18 ft
- Truss Spacing = 24 inches
1. Calculate Trusses Needed:
Trusses Needed=2420×12+1
Trusses Needed=24240+1=10+1=11 trusses
2. Maximum Span Capacity:
Since the span is entered as 18 ft:
Maximum Span Capacity=18×0.9=16.2ft
FAQs
1. How do I know how many floor trusses I need?
You can calculate the number by dividing the room width (in inches) by the spacing between trusses and then adding one additional truss.
2. What is the standard spacing for floor trusses?
The most common truss spacings are 16 inches and 24 inches on center, depending on load requirements and building codes.
3. How far can a floor truss span?
Depending on depth and material, typical residential floor trusses can span 15 to 40 feet without interior supports.
4. Why add an extra truss when calculating?
An extra truss ensures you have proper framing at both ends of the span — providing full support and maintaining structural integrity.
Check out 1 similar Floor Truss Calculator– Estimate Trusses Needed and Maximum Span Capacity :