Roofing materials checklist (what you forget when estimating)
A practical checklist for roofing orders: squares, bundles, waste, and the accessory items that often get missed in basic estimates.
Squares, bundles, and why the label matters
A roofing square is 100 sq ft of roof surface area. Many shingles are packaged so that a certain number of bundles covers one square, but the exact number varies by product. Always confirm on the wrapper or product spec sheet.
If you estimate bundles using a generic assumption and it is wrong for your shingle, your order can be off by several bundles even when the square count is correct.
Waste factors (typical starting points)
Waste depends heavily on roof complexity. Even with the same surface area, a roof with valleys, hips, dormers, and many penetrations will require more cuts and thus more waste.
| Roof complexity | Common waste | Why it increases |
|---|---|---|
| Simple gable | 10–15% | Fewer cuts and valleys |
| Typical mixed roof | 15–20% | More edges and penetrations |
| Complex roof | 20–25%+ | Valleys, dormers, many cuts |
Accessory checklist (often missed)
- Starter strips
- Ridge cap shingles (or ridge cap system)
- Underlayment (felt or synthetic)
- Ice & water shield (where required by code/climate)
- Drip edge
- Step flashing / chimney flashing / valley flashing (project dependent)
- Roof vents / ridge vent components
- Nails and sealants
Pitch and measurement: footprint is not roof area
Roof surface area is larger than footprint area on pitched roofs. If you are estimating from the ground, apply a pitch multiplier or measure each plane. The most common big error is mixing footprint dimensions with slope dimensions.
If you are unsure, use the roof pitch multiplier approach as a planning estimate and confirm with a roofer or by measuring planes.
Roof pitch multipliers (quick table)
If you only know the footprint area, multiply by a pitch multiplier to estimate roof surface area. This is a planning tool—complex roofs should be measured by planes when possible.
| Pitch | Multiplier (approx.) | Note |
|---|---|---|
| 4/12 | 1.054 | Low slope |
| 6/12 | 1.118 | Common |
| 8/12 | 1.202 | Steeper, more waste risk |
| 10/12 | 1.302 | Steep |
| 12/12 | 1.414 | Very steep |
Starter strips and ridge cap (why they add up)
Starter strips and ridge cap shingles are often separate SKUs. Even if your shingle bundle math is right, missing these items is a common cause of last-minute trips and color mismatches.
- Starters are planned by linear feet of eaves/rakes (project dependent).
- Ridge cap is planned by linear feet of ridge/hip length (project dependent).
- If you add ridge vent, include ridge vent components and compatible cap requirements.
Squares to bundles (quick example)
Example: if your roof is 22 squares (2200 sq ft) and your shingle is packaged at 3 bundles per square, you plan 22 × 3 = 66 bundles. Then apply your waste factor and round up to whole bundles.
Round-up and delivery planning (per SKU)
Round up by product line item, not just total bundles. Field shingles, ridge cap, starter, and underlayment often have different coverage rates and packaging rules.
If you need to split orders, keep lot/batch consistent when possible and plan where bundles will be stored dry and flat to prevent damage.
- Track field shingles, ridge cap, starter, and underlayment as separate line items.
- Confirm bundle coverage on each wrapper; similar products can differ.
- Plan delivery access and staging before the truck arrives to reduce breakage.
Buying strategy (avoid shortages and mismatches)
- Round up to whole bundles and keep a small number of extras for repairs.
- Buy all shingles and ridge cap from the same batch when possible to reduce color mismatch risk.
- Plan delivery placement and weather windows; storage and staging affect damage and waste.