What does a $450 to $1,200 'per square' roofing quote mean?

Per-square pricing is how Greater Victoria roofers actually think, and it explains the local surprise that a small house can have a big roof. A 1,200 sq ft Sidney rancher with wide eaves runs 14 or 15 squares; a 2,400 sq ft three-storey townhouse in Langford's Westhills can be under 10. The floor area you know from your assessment tells you almost nothing until it is turned into squares, which is why the calculator starts from storeys and pitch.

The low end of the published range, $450 a square, belongs to a simple gable on a newer Colwood or Royal Bay subdivision home with driveway access and a basic laminate shingle. The high end belongs to a steep Rockland or Uplands roof with hips, valleys, two chimneys and hand-carried materials, or to premium shingles. Metal and cedar sit above the range altogether: our model prices metal at $1,200 to $2,400 per square and cedar at $1,400 to $2,800.

Take the footprint of the house (floor area divided by storeys), add about 10 percent for eaves and rake overhangs, then multiply by a pitch factor: roughly 1.03 for a low slope, 1.09 for a moderate 4/12 to 6/12, and 1.25 for 7/12 and steeper. Divide by 100. A 1,000 sq ft footprint at moderate pitch is 1,000 × 1.1 × 1.09 = about 1,200 sq ft, or 12 squares. Roofers measure more precisely from the ground, from satellite imagery or on the roof, but this gets you within a square or two.

• Footprint = floor area ÷ storeys
• Add 10% for overhangs
• Multiply by pitch factor (1.03 / 1.09 / 1.25)
• Divide by 100 for squares

An installed per-square rate normally covers tear-off of one layer, disposal, underlayment, standard flashings, the shingles, ridge venting and cleanup. It does not cover a second layer, decking replacement, chimney or skylight re-flashing, or structural work; those are lump-sum lines. Two quotes can show the same per-square rate and differ by thousands on those extras, so read below the rate.

From $450 to $1,200 is nearly a factor of three, and pitch, storeys, access, shingle grade and how cut-up the roof is account for it. In our model a steep pitch alone multiplies the labour by 1.15 and the area by 1.25; difficult access adds up to 12 percent; a third storey adds 12 percent. A designer shingle can add a few dollars per square foot over a standard laminate. When a contractor gives you a per-square number, ask which end of the range your roof sits at and why.