Roof anatomy
Deck, air and vapor control, insulation, underlayment, flashing, drainage, ventilation, and the visible covering.
Not published yet
Roof types
A roof is a system, not a surface.
Learn the shape, slope, covering, layers, edges, drainage, and building conditions that make one roof work differently from another.
30-second answer
How do I choose the right roof type?
Start with the building and the roof’s slope—not a material brochure. A good choice must fit drainage, structure, climate, access, maintenance, ownership horizon, and budget as one system.
Geometry first
Slope decides how much roof you are buying.
Two buildings with the same footprint do not buy the same roof. Before any material comparison, pitch sets the surface area that every quantity, every allowance, and every price is calculated from.
| Pitch | Surface multiplier | Roof surface | Roofing squares |
|---|---|---|---|
| 2:12 | ×1.0138 | 1,825 sq ft | 18.2 |
| 3:12 | ×1.0308 | 1,855 sq ft | 18.6 |
| 4:12 | ×1.0541 | 1,897 sq ft | 19.0 |
| 5:12 | ×1.0833 | 1,950 sq ft | 19.5 |
| 6:12 | ×1.118 | 2,012 sq ft | 20.1 |
| 7:12 | ×1.1577 | 2,084 sq ft | 20.8 |
| 8:12 | ×1.2019 | 2,163 sq ft | 21.6 |
| 9:12 | ×1.25 | 2,250 sq ft | 22.5 |
| 10:12 | ×1.3017 | 2,343 sq ft | 23.4 |
| 11:12 | ×1.3566 | 2,442 sq ft | 24.4 |
| 12:12 | ×1.4142 | 2,546 sq ft | 25.5 |
That is geometry, not a takeoff. Measure the plan area to the edge of the eaves—overhangs are part of the footprint you start from, which is what the estimator asks for. What the multiplier cannot do is account for dormers, a second pitch, parapets, porches, or separate structures; a real quantity is measured plane by plane.
Available today
Two of these already work.
The guides in the coverage map below are unwritten. These two pages are published, ungated, and useful while you are still narrowing a material list.
Open the beta cost estimator
Choose a material family, a pitch, and a complexity level, and see a national planning range with the formula shown.
Read how roof area is calculated
The pitch multiplier, a worked example, and the measurement problems no multiplier can solve for you.
Coverage map
What each roof-types guide will have to answer.
Nothing in this map is published yet. It is here so the scope is visible in advance—and so the finished guides can be held to it.
Shapes & slopes
Gable, hip, shed, mansard, gambrel, flat and low-slope designs—plus how pitch changes area and options.
Not published yet
Residential materials
Asphalt, metal, wood, tile, natural slate, synthetic systems, and residential low-slope membranes.
Not published yet
Commercial assemblies
TPO, EPDM, PVC, modified bitumen, built-up roofing, coatings, insulation, drainage, and edges.
Not published yet
Climate fit
Snow, ice, wind-driven rain, salt, heat, humidity, fire exposure, hail, and maintenance realities.
Not published yet
Compare the tradeoffs
Upfront cost, planning life, repairability, weight, appearance, disruption, and lifecycle cost.
Not published yet
Next step
Turn a material shortlist into a buying plan.
The buying kit’s quote checklist is published as an ungated preview. Use it to make every installer define the same scope against the system you chose.
Preview the buying kit