ποΈ Types of Steel Frame Trusses
Steel frame trusses come in various configurations depending on roof slope, span, and load requirements. Here are the most common types used in construction:
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Mono-Pitch Truss
Single slope design. Ideal for lean-to structures, carports, and additions to existing buildings. Slope: 5-15%.
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Gable Truss (A-Frame)
Classic triangular shape with two equal slopes. Most common for residential construction. Provides excellent water drainage.
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Scissor Truss
Creates vaulted ceiling effect. Bottom chord slopes upward creating cathedral-style interiors. Popular for living rooms.
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Flat Truss
Minimal slope (2-5%) for modern flat roof designs. Requires proper waterproofing membrane. Common in commercial buildings.
π How to Calculate Truss Height
The height of a truss depends on the desired slope and the span (width) of the structure. Use these formulas to calculate the correct dimensions:
Height Calculation Formula
Height = (Slope % Γ Span) / 100
Example 1:
Span: 6m, Slope: 10% β Height = (10 Γ 600) / 100 = 60cm
Example 2:
Span: 8m, Slope: 15% β Height = (15 Γ 800) / 100 = 120cm
Recommended Slopes by Roof Type
| Roofing Type |
Min. Slope |
Recommended |
Height (6m span) |
| Corrugated Metal / Zinc |
5% |
10-15% |
60-90cm |
| Ceramic Tiles |
15% |
20-30% |
120-180cm |
| Polycarbonate |
3% |
5-10% |
30-60cm |
| Waterproof Membrane |
2% |
3-5% |
18-30cm |
π Calculation Methodology for Steel Frame Roof Trusses
Steel frame roof trusses are prefabricated triangular structures used in sloped roofs. This calculator implements construction standards for precise calculations of profiles, studs, and slopes.
π© Vertical Studs
Studs are the internal vertical profiles of the truss. They connect the bottom chord to the top chord and their height varies progressively according to the roof slope.
π Top and Bottom Chords
The bottom chord is horizontal and defines the truss width. The top chord is inclined and longer due to the slope angle.
π Slope Calculation
Slope is calculated automatically: % = (Initial height - Final height) / Length Γ 100. Slopes of 5-15% are typical for proper water drainage.
π§ Fasteners
8 screws per linear meter of profile are calculated for all stud-chord connections. Use self-drilling pan head screws 8mm.
β Frequently Asked Questions about Steel Frame Trusses
What is the standard spacing between studs in a truss?
Standard spacing is 16" to 24" (40-60cm) depending on roof load. For heavy tiles or roofing, use 16". For lightweight covers like metal or polycarbonate, up to 24" can be used.
What minimum slope do I need for a metal roof?
For corrugated metal roofing, the minimum recommended slope is 5% (3Β°). However, for better drainage and durability, 10-15% (6Β°-9Β°) is recommended.
How many trusses do I need per linear foot of roof?
Typically one truss is installed every 32" to 48" (80-120cm) of roof length. For a 30ft long roof you would need approximately 9-13 trusses. Use this calculator to add multiple trusses.
How do I calculate the height of my truss?
Use the formula: Height = (Slope % Γ Span) / 100. For a 6m span with 10% slope, the height would be 60cm.