Inputs
Roof Zone Map & Weighting
Corner > Edge > Field (uplift severity)
Corner
Edge
Field
Corner
%
Edge
%
Field
%
Values will normalize to 100% during calculation.
Corner
Edge
Field
Weighted with Cnet to compute adjusted uplift.
Zone-weighted factor Z
—
Adjusted Cnet = Cnet · Z
—
Results
Array area
— m²
Velocity pressure q
— Pa
Uplift pressure p = q·Cnet,adj
— Pa
Dead load (panels+mounts)
— kN
Net uplift demand (with SF)
— kN
Required ballast mass
— kg
Ballast per panel
— kg/panel
Estimated ballast blocks
— blocks
Required anchors
— count
Total system weight
— kg
Distributed load
— kPa (— psf)
| Metric | Value | Units |
|---|---|---|
| Array area | — | m² |
| Velocity pressure q | — | Pa |
| Zone-weighted factor Z | — | — |
| Adjusted Cnet | — | — |
| Uplift pressure p | — | Pa |
| Dead load | — | kN |
| Net uplift demand | — | kN |
| Required ballast mass | — | kg |
| Ballast per panel | — | kg/panel |
| Estimated ballast blocks | — | blocks |
| Required anchors | — | count |
| Total system weight | — | kg |
| Distributed load | — | kPa |
| Distributed load | — | psf |
Formula Used
- Array Area: \(A = n \cdot L \cdot W\) unless a custom area is provided.
- Velocity Pressure: \(q = 0.613 \cdot K \cdot V^2\) where V is wind speed (m/s) and K is a user-set multiplier for height, exposure, and topography.
- Zone-weighted Factor: \(Z = \frac{w_f M_f + w_e M_e + w_c M_c}{w_f + w_e + w_c}\), where \(w\) are area fractions and \(M\) are zone multipliers (field, edge, corner).
- Adjusted Uplift Pressure: \(p = q \cdot (C_{net} \cdot Z)\).
- Uplift Force: \(F_{up} = p \cdot A\) (N).
- Dead Load: \(W_d = (n \cdot (W_p + W_m)) \cdot g\) (N), with \(g = 9.80665\ \text{m/s}^2\).
- Net Uplift Demand: \(R = \max(0, SF \cdot F_{up} - W_d)\). Reported in kN.
- Ballast Mass: \(M_b = R / g\) (kg). Per-panel ballast is \(M_b / n\).
- Anchors: Count \(= \lceil R / \text{AnchorCapacity} \rceil\).
- Distributed Load: \(p_d = (W_{total} \cdot g) / A\) (Pa) and psf \(= p_d \cdot 0.020885\).
These are simplified calculations for preliminary sizing only. For final design, consult the governing standard and a licensed structural engineer.
How to Use
- Enter wind speed and units. Adjust K for exposure and height.
- Provide panel count, dimensions, and weights. Add mount weight if known.
- Use a custom array area if gaps or spacing are significant.
- Set Cnet baseline, then assign zone split and multipliers.
- Optionally enter anchor capacity and ballast block size.
- Click Calculate. Export results to CSV or PDF for records.
Example Data
| Scenario | Wind | Cnet | K | Panels | L×W (m) | Panel+Mount (kg) | Zone Split (C/E/F) | Anchor Cap (kN) |
|---|---|---|---|---|---|---|---|---|
| Low wind residential | 30 m/s | 0.9 | 0.9 | 10 | 1.75 × 1.10 | 24 | 10 / 20 / 70 | 2.0 |
| High wind coastal | 55 m/s | 1.3 | 1.2 | 16 | 1.75 × 1.10 | 25 | 20 / 40 / 40 | 3.0 |
| Tall building downtown | 45 m/s | 1.5 | 1.4 | 12 | 1.75 × 1.10 | 26 | 25 / 35 / 40 | 2.5 |
Use the schematic to estimate how much of your array lies in each zone.
FAQs
Use the applicable design wind speed for your jurisdiction and risk category. If unsure, consult local codes or a licensed engineer.
K approximates exposure, height, and topographic effects on velocity pressure. Increase K for taller buildings, open terrain, or hill crests.
You assign the estimated share of array in corner, edge, and field zones. The tool applies your multipliers to weight uplift conservatively.
Ballast increases weight to resist uplift. Anchors transfer forces to structure. Many systems use a hybrid approach; verify roof capacity and waterproofing requirements.
This tool focuses on wind uplift. Snow, seismic, and maintenance loads may govern roof capacity checks and must be considered separately.
Results are preliminary. Authorities typically require sealed calculations following the adopted code and manufacturer requirements.