Truss Weight Calculator
A truss weight calculator multiplies roof area by a weight per sq ft, so 1,200 sq ft of roof at 3 lb per sq ft comes to 3,600 lb of trusses.
Truss weight calculator formula
A truss weight calculator estimates the total weight of the roof trusses from the roof area. Total weight (lb) = roof area (sq ft) × weight factor (lb per sq ft). The default factor is 3 lb per sq ft, which is a planning figure. The result is the weight of the trusses alone, before sheathing or roofing is added.
The formula in plain words
Find the roof area in square feet. Multiply it by how many pounds of truss there are per square foot of roof. The answer tells you the weight of the whole set. That helps you plan how to unload it, move it and lift it.
Worked examples
These match the calculator exactly.
- Small house: 1,200 sq ft of roof at 3 lb per sq ft
- Total: 1,200 × 3 = 3,600 lb
- Larger house with heavier trusses: 2,400 sq ft at 4 lb per sq ft
- Total: 2,400 × 4 = 9,600 lb
- Mid-size roof: 1,800 sq ft at 3.5 lb per sq ft
- Total: 1,800 × 3.5 = 6,300 lb
For scale, 9,600 lb is nearly 5 tons, which is more than a pickup truck can carry in one load.
Weight for 1,000 square feet of roof
| Weight factor | Total weight |
|---|---|
| 2.5 lb per sq ft | 2,500 lb |
| 3.0 lb per sq ft | 3,000 lb |
| 3.5 lb per sq ft | 3,500 lb |
| 4.0 lb per sq ft | 4,000 lb |
Scale by area. A 1,500 sq ft roof is 1.5 times these figures.
Getting the roof area
A sloped roof has more surface than its footprint. For a gable roof, find the footprint, then multiply by a slope factor. A 6 in 12 pitch has a factor of about 1.118, so a 1,000 sq ft footprint is about 1,118 sq ft of roof. Include the overhangs, since trusses extend past the walls. The roof area calculator does this for you.
What the number is used for
Weight tells you how to plan delivery and lifting. A set of trusses for a house often comes on a flatbed, and large sets are set with a crane. Crews also use the figure to decide how many people they need on the ground. After the roof is on, add the weight of sheathing, underlayment and roofing to find the load on the walls. Those loads are for an engineer to check.
Handling trusses safely
Trusses are tall and thin and can fall over. Store them on blocking off the ground and keep them upright with bracing. Lift them by the points marked on the drawings, and brace each one as soon as it is set. Temporary bracing and permanent bracing are part of the design. Follow the supplier’s instructions and ask a licensed professional about spans and bracing.
Checking the figure against the supplier
Once you have truss drawings, compare the manufacturer’s listed weights with the tool. If the drawings show a 3,600 lb total for example 1, the 3 lb per sq ft factor was about right. If the real figure is 4,500 lb, the factor for your design is 4,500 ÷ 1,200 = 3.75. Enter that next time. You can build up a good factor for your own jobs from a few real deliveries, which beats any rule of thumb.
Planning the lift
Add up the weight of the trusses you will handle at once. A crane or a lift needs a rating well above that, and the rigging must suit the length of the truss. Hand setting is common on small houses, and many crews raise trusses by tipping them up from the wall. Ask the supplier how the trusses are bundled and how many come in each bundle.
Common mistakes
- Using footprint area for a sloped roof.
- Treating the factor as exact.
- Forgetting the weight of sheathing and roofing.
- Using the weight to judge strength.
- Lifting without a plan.
Related pages
To count the trusses, see the roof truss calculator. For pricing, see the truss cost calculator. For steel beams, see the i-beam weight calculator.
Frequently asked questions
How much does a roof truss weigh?
It varies a lot with span, spacing and lumber. This tool multiplies the roof area by a weight factor in pounds per sq ft, 3 by default, so 1,200 sq ft is 3,600 lb. For an exact figure, use the truss manufacturer's drawings or delivery ticket.
What weight factor should I use?
The default of 3 lb per sq ft of roof is a rough planning number. Heavier designs, long spans or closely spaced trusses may be higher. Ask your truss supplier.
Why does truss weight matter?
It tells you what a delivery truck, a crane or a crew has to lift, and what the walls carry before the roofing goes on. It does not include sheathing, shingles or snow.
Is roof area the same as the footprint?
No. Sloped roofs have more surface than the floor beneath them. Use the roof area, which you can find from the footprint and pitch.
Can this tell me if my framing is strong enough?
No. Truss design and bracing are engineering matters. Use truss drawings from the supplier, and ask a licensed engineer if you have questions.
Estimates only. Verify quantities with your supplier before purchasing.