Roof Pitch Calculator South Africa 2026 (Shed & Gable Slope, Degrees, Rafters & SANS 10400)
Calculate shed and gable roof pitch degrees, rise-to-run slope ratios, and true rafter cut lengths in South Africa. Verify SANS 10400-L minimum slope requirements for IBR sheeting, corrugated iron, and concrete roof tiles.
Roof Pitch Calculator South Africa
Methodology
Calculates geometric roof slope, pitch angle in degrees, pitch percentage, and hypotenuse rafter length including horizontal eaves overhang for mono-pitch (shed) and dual-pitch (gable) roof structures. Validates results against South African National Standard SANS 10400 Part L (Roofing) minimum pitch specifications (IBR/Klip-Lok: min 5°, Corrugated: min 10°, Concrete Tiles: min 17.5° with underlay, min 26° standard).
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User-provided inputs
This calculator uses only the values you enter. It does not automatically apply tax law, statutory deductions, lender fees, or live exchange rates.
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Formula basis
The formula is shown openly and no country rate is inserted automatically.
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Your estimate
AfricalHub is an independent private platform not affiliated with any government agency. Calculations are for educational planning only. Verify official filings with the relevant revenue authority or a qualified professional.
SANS 10400-L Minimum Roof Slope Standards in South Africa
| Roof Cladding Material | Minimum SANS 10400 Pitch | Slope Ratio | Installation Requirements |
|---|---|---|---|
| Concealed-Fix / Klip-Lok Sheeting | 2.0° – 5.0° | 1 : 28 to 1 : 11 | No pierced fixings, continuous long sheets |
| Inverted Box Rib (IBR) Sheeting | 5.0° | 1 : 11 (8.7%) | Sealed side-laps on slopes under 7.5° |
| Corrugated Iron Sheeting | 10.0° | 1 : 5.7 (17.6%) | Broad flute laps, heavy fasteners |
| Interlocking Concrete Tiles (with undertile plastic) | 17.5° | 1 : 3.17 (31.5%) | Mandatory SANS-approved undertile membrane |
| Standard Concrete / Clay Tiles (open batten) | 26.0° | 1 : 2.05 (48.8%) | Standard timber batten spacing |
Sources
User-provided inputs
This calculator uses only the values you enter. It does not automatically apply tax law, statutory deductions, lender fees, or live exchange rates.
Frequently asked questions
What is the minimum roof pitch for IBR and Corrugated sheeting in South Africa?
Under SANS 10400-L, IBR and concealed-fix sheeting (such as Klip-Lok) can be installed down to a minimum pitch of 5° (approx 1:11 slope). Standard corrugated iron sheeting requires a minimum pitch of 10° (1:6 slope) to prevent rain backflow during summer highveld downpours.
What is the minimum roof pitch for concrete roof tiles in South Africa?
Standard interlocking concrete roof tiles (like Coverland or Marley) require a minimum pitch of 17.5° when installed with an approved waterproof undertile membrane (plastic underlay). For roofs without specialized undertile plastic, the minimum required slope is 26°.
How do you calculate rafter length from span and rise?
Using the Pythagorean theorem: Rafter Length = √(Run² + Rise²). For a gable roof, Run is half the building span (Span ÷ 2). For a shed (mono-pitch) roof, Run equals the full building span. An eaves overhang adjustment (typically 300mm to 600mm) is added.