Metal Roofing Material Estimator

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Category Roofing

1. Roof Configuration

Roof Shape

Units

Imperial (ft/in)Metric (m/mm)

2. Dimensions

Building Length (ft)

Building Width (ft)

Overhang (in)

Roof Pitch (Rise / 12)Example: 4 means 4:12 pitch

3. Material Details

Panel Profile

Effective Coverage (in)

Panel Length (Max Avail)

End Lap (in)

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About

Precise material estimation for metal roofing prevents costly mid-project shortages or excessive waste. This tool calculates the exact number of panels required based on effective coverage width, not total width, accounting for critical side laps (typically 1 rib or 25 to 50 mm) and end laps (150 mm). It adjusts for roof pitch, converting horizontal plan dimensions into actual slope lengths using trigonometric multipliers.

Waste management in metal roofing is geometric. Cutting panels for hip or valley roofs generates significant offcut waste that cannot always be reused. This estimator applies specific waste factors based on the selected roof shape (Gable, Hip, or Shed) and panel profile (Corrugated, R-Panel, Standing Seam), ensuring the generated shopping list for sheets, ridge caps, and fasteners (5 to 7 per m²) reflects site realities.

Formulas

The actual slope length (L_slope) is derived from the horizontal run (L_run) and the pitch angle (θ) or pitch ratio (P):

L_slope = L_runcos(θ)

Total panels required (N_panels) depends on roof length (L_roof) and the effective coverage width (W_eff) of the material, not the physical width:

N_panels = ceil(L_roofW_eff) × Rows

Fastener count (C_screw) is estimated by area (A) and density (d):

C_screw = A × d × (1 + Waste_%)

Reference Data

Profile Type	Total Width	Effective Coverage	Min. Side Lap	Typical Gauge
Corrugated 7/8″	26″ / 660mm	24″ / 610mm	1.5 Corr.	26-29 ga
R-Panel (PBR)	38″ / 965mm	36″ / 914mm	1 Rib	22-26 ga
Standing Seam	16″ / 406mm	16″ / 406mm	Locked Seam	22-24 ga
Corrugated 3″	33″ / 838mm	30″ / 762mm	1 Rib	20-24 ga
Trapezoidal Metric	1050mm	1000mm	1 Rib	0.4-0.6 mm
Tile Effect Sheet	1100mm	1050mm	1 Step	0.45-0.55 mm
Ag Panel	38″ / 965mm	36″ / 914mm	3/4″ Rib	29 ga
V-Crimp	26″ / 660mm	24″ / 610mm	Overlap	26 ga

Frequently Asked Questions

Yes. A standard corrugated sheet might be 26 inches wide physically, but due to the required side overlap (lapping one corrugation over another to seal out water), it only covers 24 inches of the roof. Ignoring this leads to a material shortage of roughly 8%.

A 4:12 pitch means the roof rises 4 units for every 12 units of horizontal run. The angle is arc-tangent(4/12), roughly 18.4 degrees. This tool handles that conversion automatically.

For exposed fastener systems (like Corrugated or R-Panel), typical density is 5 to 7 screws per square meter (approx. 50-70 per square (100 sq ft)). High-wind zones may require denser patterns. Standing seam roofs use concealed clips, which are calculated differently (usually one per 12-24 inches of seam).

Hip roofs require cutting panels at angles for the hips and valleys. While straight gable roofs might only have 3-5% waste, complex hip roofs can see 10-15% waste due to unusable triangular offcuts.