⌂ RoofingCalculatorHQ

Hip Roof Calculator (Canada)

Free hip roof calculator for Canada. Compute surface area, common and hip rafter lengths, and ridge length to NBC 9.23 — supports both ft and metres, X/12 and degrees.

Hip Roof Calculator

|
Roof surface area
1502.64
ft² · slope ×1.118 · 26.6°
Common rafter
17.89
ft
Hip rafter
24
ft
Ridge length
10
ft
Roofing squares
15.03
1 sq = 100 ft²

How this hip roof calculator works for Canadian projects

Enter the building length, width, eave overhang, and pitch (in X/12 by default for anglophone Canada, with degrees available). The calculator returns the roof surface area (sq ft or m²), the common rafter length, the hip rafter length, the ridge length, and the equivalent in roofing squares.

The hip is the default residential roof shape across most of Canada because it sheds snow on all four sides — important in any climate zone above 1.5 kPa ground snow. NBC 9.23 (light wood-frame construction) prescribes the structural rules; CRCA’s Roofing Specifications Manual prescribes the waterproofing detail.

The math, derived

Slope factor:

slope factor = sqrt(1 + (rise/run)²) = sec(angle)

For Canadian pitches: 4/12 = 1.054, 6/12 = 1.118, 8/12 = 1.202, 9/12 = 1.250, 12/12 = 1.414.

Surface area

For an equal-pitch hip on a rectangular footprint:

hip surface area = (length + 2·overhang) × (width + 2·overhang) × slope factor

The total area equals the gable equivalent — the four hip planes sum exactly to the rectangle of the footprint times the slope factor.

Rafters

common rafter = (W/2) × slope factor
hip rafter    = (W/2) × √(2 + (rise/run)²)

NBC 9.23 Tables 9.23.4.2 give rafter span limits for Spruce-Pine-Fir No. 2 grade — the standard Canadian framing species. Hip rafters typically need to be one size up from the commons because they carry more load and span further (their own length plus the jack rafter loads on either side).

Ridge

ridge length = length − width

A 40 ft × 28 ft Canadian bungalow hip has a 12 ft ridge regardless of overhang. Square footprint = pyramid hip with no ridge.

Canadian pricing context (2026)

From recent CRCA, HomeStars, and Renomii contractor quotes:

MaterialC$ / sq ft installedHip premium vs gable
Architectural asphalt (BP, IKO, Owens Corning)C$5.50–C$7.75+C$0.50–C$1.00 / sq ft
Premium designer asphaltC$8.00–C$11.50+C$0.75–C$1.50 / sq ft
Steel shingle (Vicwest, Metal Roof Outlet)C$11.00–C$15.50+C$1.50–C$2.50 / sq ft
Standing-seam steelC$13.00–C$18.00+C$2.00–C$3.00 / sq ft
Cedar shakeC$13.00–C$18.50+C$2.50–C$4.00 / sq ft
Slate (Glendyne or imported)C$28.00–C$48.00+C$4.00–C$8.00 / sq ft

A 1,800 sq ft hip in Toronto in mid-grade architectural asphalt runs roughly C$13,500–C$15,000 installed including the hip premium, ice-and-water shield around all four eaves, and CRCA-compliant ridge ventilation.

Common Canadian mistakes

Underestimating snow drift on the lee side. NBC requires designers to consider snow drift loading per Part 4 — even on a hip, the lee side can carry up to 1.5× the basic snow load when wind drives drifts off an upper roof onto a lower hip. Engineer sign-off catches this; back-of-envelope sizing often misses it.

Skipping ice-and-water shield in valleys. Hip valleys are where ice dams form first. CRCA strongly recommends ice-and-water shield up every hip valley regardless of climate zone. OBC 9.26.6 makes it mandatory in zones above 1.5 kPa ground snow.

Forgetting the metric conversion on tile orders. Quebec roofing material is sold in m² for tile and in squares (100 sq ft) for asphalt. A 1,800 sq ft hip is 167 m². Mixing the two on the same purchase order is one of the most common quantity-takeoff errors on bilingual projects.

Under-ordering hip cap. Hip cap goes down all four hip lines plus the ridge. For a typical 1,800 sq ft hip that is roughly 95–110 linear feet of cap — usually 4 to 5 bundles of asphalt hip-and-ridge cap (BP Mystique, IKO Hip & Ridge, Owens Corning ProEdge).

Standards and references

  • NBC 2025 — Part 9.23 (light wood-frame construction), 9.26 (roofing).
  • CRCA Roofing Specifications Manual — steep-slope and low-slope assemblies.
  • CSA O86 — Engineering design in wood (for structural rafter calculations).
  • CSA A123 series — Asphalt shingles, underlayment, and roll roofing.
  • Provincial codes — OBC (Ontario), RBQ (Quebec), BCBC (British Columbia), Alberta Building Code.

Using this with the rest of the project

Once you have the area, size the framing with the roof truss calculator, price the covering with the roof cost calculator, and validate the pitch with the roof pitch calculator. For a like-for-like comparison with a gable, run both through the roof area calculator — the area is identical; the hip premium is in labour, hip cap, and 2–5% extra waste.

The hip is the default Canadian residential roof shape. Get the geometry right and every downstream cost — material, labour, ice-and-water shield, ridge ventilation, engineer sign-off — falls into a clean, defensible package.

Frequently asked questions

What pitch is typical for a Canadian hip roof?
Most Canadian residential hips fall between 4/12 and 9/12 (18° to 37°). Steeper pitches help shed snow in Quebec, the Maritimes, and northern Ontario — the NBC 9.23 minimum slope for asphalt shingles is 2/12 (with double underlayment) or 4/12 (single underlayment). Mountain markets like Whistler and Banff favour 8/12 to 12/12 to handle snow loads up to 4.5 kPa.
How does NBC snow load affect the calculation?
Snow load does not change the geometric area. It changes the rafter and truss size that the engineer specifies. NBC Part 4 (and Part 9 for small buildings) reference NBC Climate Data tables for ground snow Ss and rain load Sr, which combine into roof snow load via the slope factor Cs. For a 6/12 hip in Toronto (Ss = 1.7 kPa), Cs ≈ 0.85, giving roughly 1.45 kPa of design snow on the roof.
Can I use this for a square pyramid hip?
Yes. Enter equal length and width — the ridge length will compute as 0 (a true pyramid hip with no ridge board, just four hip rafters meeting at the apex). Common on Victorian-era turrets and modern porch covers.
What waste percentage do Canadian roofers use for a hip?
CRCA and Renomii data: 10% for asphalt shingles on a simple gable, 12–15% on a hip with valleys, and 15–18% on a hip with multiple dormers or complex returns. Add 2–3% extra in winter installation conditions because of the increased breakage on cold shingles below 4°C.
Do I need ice-and-water shield on a hip?
Yes. NBC 9.26.6 (and provincial equivalents — OBC 9.26 in Ontario, RBQ in Quebec) requires self-adhered eave protection from the eave to a point 900 mm inside the inner face of the exterior wall. On a hip this means a continuous strip around all four eaves, not just the gable returns. Also recommend ice-and-water shield up every hip valley if any dormers create concave junctions.
Should I use X/12 or degrees for a Canadian hip?
Both. Anglophone Canadian framers use X/12 (legacy of US framing tradition). Quebec and engineering documentation use degrees. The calculator accepts either and produces identical area results. For a 6/12 input, the equivalent is 26.6°.

Related calculators