This guide covers what waste includes, why geometry drives it, where the number comes from, how it's applied, and what to send when a reviewer asks about it. It's about documenting the scope of the work you perform. What a carrier approves is the carrier's decision.
What waste covers on a roof estimate, unit: %
Waste is field material you have to buy but can't install as full pieces. Hover's measurements glossary defines waste factor as the percentage of material ordered beyond the estimated amount needed for construction. On a shingle roof, most of it comes from cutting.
- Hips and valleys
- Every hip is a cut line on both of the facets that meet there. A valley is cut on one or both sides, depending on the valley method. Cutoffs along a valley are often too small to use anywhere else on the roof.
- Rakes
- Each course ends at the rake, usually with a cut piece, unless the run comes out even with the shingle length.
- Dormers, walls and chimneys
- Each obstruction breaks courses into short runs, and short runs mean more cuts for each square installed.
- Damaged pieces
- Some shingles get damaged in handling or have to come off after a fastening mistake. Builder-written estimating guidance counts this as part of real-world waste.
Why roof shape drives the waste figure
Waste rises with the number of cut lines per square, so two roofs with the same area can need very different waste. A simple gable with two planes is cut mainly at the rakes. A hip roof swaps the rakes for hips, and each hip is cut along both sides for its full length. Add valleys, dormers, and small facets, and the cutting adds up quickly.
Fine Homebuilding's shingle estimating guidance says the same: waste goes up with every obstruction and every hip or valley. Take the figure from this roof, not the last job.
| Feature | Where the cuts happen | What to take from the report |
|---|---|---|
| Rakes | The end of each course at the gable edge | Rake length (LF) |
| Hips | Both facets, along the full hip line | Hip length (LF) |
| Valleys | One or both sides, depending on valley method | Valley length (LF) and valley type from your photos |
| Dormers and small facets | Short courses with several edges in a small area | Facet count and area per facet |
| Walls, chimneys, skylights | Course breaks around each obstruction | Wall flashing length (LF) and penetration count |
Where the waste figure comes from
The two sources that are easiest to document are a measurement report that calculates waste from the roof's geometry, and a measured sketch of the roof in your estimating platform. Here is what three report vendors publish about waste on their own sites.
- EagleView
- In a July 2019 announcement, EagleView introduced a Suggested Waste Factor. It described the feature as using roof measurement data specific to each property and a proprietary algorithm, and said it was available in all residential 3D roof reports. A 2020 EagleView blog post shows a report on a complex 12-sided roof, planned as a metal roof, with a suggested waste of 41%.
- Hover
- Hover's help center describes a recommended roof waste percentage that you can apply to roof templates in its Material List, job by job. Hover says its roof-only report covers roof facets, pitches, ridges and hips, valleys, rakes, eaves, flashing, step flashing and drip edge.
- Roofr
- Roofr's blog says its measurement reports calculate roofing waste for you.
- A measured sketch
- If you measured by hand or drew the roof in your platform, the sketch gives you the same inputs: facets, pitch, and hip, valley and rake lengths. Note who measured it and when.
Whatever the source, read the notes printed with the waste figure before you use it. Check whether hip, ridge and starter are counted or left out, and which roof areas (by pitch or material) the figure covers. A suggested figure is a starting point for your judgment, not a standard.
How waste is applied in an estimate
Waste is applied to the field shingle quantity: the measured roof area plus the chosen percentage. Starter and ridge are priced on their own lines from linear measurements.
Xactware's help center describes two ways to set roof waste in Xactimate desktop (X1): by hand on roofing material items (choosing a value, or typing a specific percentage into the quantity calculation), or with a preference that calculates roof waste automatically. That article doesn't say what the automatic calculation is based on or how it interacts with a manual entry. Check how it behaves in your version and settings, and which items it touches, before you rely on it. For other platforms, check their own documentation.
Checklist / How waste is applied5 items
Apply waste once
- One waste figure on the field shingle line, applied the way your platform's current settings apply it
- Starter on its own line (eave length, plus rake length where the manufacturer's instructions call for it), not also built into the waste percentage
- Hip and ridge cap on its own line from hip and ridge lengths, not also built into the waste percentage
- If your setup applies waste to other items, that matches the method you describe in your notes
- The area the percentage is applied to matches the report: same structure, same facets
Example (hypothetical, round numbers): Two roofs each measure 30 squares: a simple gable, and a hip roof with two valleys and two dormers. If their reports suggested 10% and 15%, the field shingle quantities would be 33 and 34.5 squares before rounding, with starter and ridge cap on separate lines. The percentages are only illustrations.
When a reviewer questions the waste figure
Questions about waste usually come down to a few points, and each one has a specific answer in the file. Send the documents with the estimate so the reviewer doesn't have to ask.
| The question | What addresses it |
|---|---|
| Why this percentage and not a flat figure? | The report's waste table (with the page number), the facet count, hip and valley lengths, and overview photos of every slope |
| Are starter or ridge counted twice? | The report's note on what its waste figure includes, plus separate starter and ridge lines with lengths from the report |
| The figure doesn't match the report | A note saying which figure you used and why (a sketch you measured, a structure the report left out, an area the table doesn't cover) |
| Part of the roof is a different material or a low slope | The report's note on which areas its figure covers, and a separate figure for that area with its basis stated |
| The quantity doesn't match the area | The arithmetic: measured area, the waste percentage, and the resulting quantity |
If you can't support a figure with these documents, revisit it before the file goes out. One number you can't back up makes the rest of the file harder to trust. Coverage questions go to the carrier, a licensed public adjuster or an attorney.
Rules of thumb, and why they disagree
Published rules of thumb vary widely, which is why a figure taken from the roof's geometry is easier to support than a remembered percentage. Some sources suggest:
- Roofr
- Its blog suggests a roofing waste factor of around 10% to 15% of the total material needed, with more adjustment for roofs with many valleys, hips and dormers.
- Fine Homebuilding
- A builder's shingle estimating article says he figures about 1% for a simple roof and 5% or more for a complex roof with open valleys, and that no calculation tells you exactly how many extra shingles you'll need. He's describing ordering material for his own crews.
These were written for different purposes (ordering versus estimating), and the EagleView example above, on a complex roof planned in metal, shows how far one roof's suggested figure can sit from either. Use them as a sanity check, not as the basis for a line.
Waste checklist before the estimate goes out
Checklist / Checklist9 items
Before the file goes out
- The full measurement report is attached, including the waste table page (what to send with the report)
- The waste figure comes from the report or a measured sketch, not from memory
- You've read the notes with the waste table: what it leaves out and which areas it covers
- Facet count and hip, valley and rake lengths are in the file
- Overview photos show every slope, dormer and valley
- Starter and ridge cap are on separate lines, from linear measurements
- Waste is applied once, to the field shingle line, in line with your platform's current settings
- Each structure (house, detached garage) has its own figure
- The waste note says which figure you used and why
If you'd rather hand off the estimate itself, our Estimators write Xactimate estimates. To talk it through, request an intro call.
Common questions
What is a normal waste factor for a roof?
No one percentage fits every roof, because waste depends on the roof's shape. Published rules of thumb disagree: one builder figures about 1% for a simple roof, while one report vendor suggests around 10% to 15%. The figure that's easiest to support comes from the report's waste table or a measured sketch.
How do you calculate shingle waste?
Multiply the measured roof area by one plus the waste percentage: 30 squares at a hypothetical 10% is 33 squares before rounding. Convert to bundles using the coverage printed on the product you install, and figure starter and ridge cap separately.
Why does a hip roof need more waste than a gable roof?
A hip roof has more cut lines per square. Each hip is cut along both facets that meet there, while a simple gable is cut mainly at the rakes. Valleys and dormers add more.
Does the waste factor include starter and ridge cap?
Keep them on their own lines, measured in linear feet. Read the notes with your report's waste table to see what its figure includes, so nothing is counted twice.
What is suggested waste on a measurement report?
It's a waste percentage the report vendor calculates from the measured roof, such as EagleView's Suggested Waste Factor or Hover's recommended roof waste. Treat it as a starting point, and note in the file if you used a different figure and why.
Does Xactimate calculate roof waste automatically?
Xactware's help center describes a preference in Xactimate desktop that calculates roof waste automatically, plus a manual method. That article doesn't say what the automatic calculation is based on, so check how it works in your version and settings before relying on it.
Sources
- Xactware help center, "Calculating roof waste" (manual and automatic roof waste in Xactimate desktop) xactware
.helpdocs (opens in a new tab).io - EagleView, Suggested Waste Factor announcement, July 18, 2019 eagleview
.com (opens in a new tab) - EagleView blog, "No Way This Waste Factor is So High! …Or Is There?", October 28, 2020 eagleview
.com (opens in a new tab) - Hover help center, "Roof recommended waste" help
.hover (opens in a new tab).to - Hover, Measurements Reports (roof-only report contents) hover
.to (opens in a new tab) - Hover help center, "The Hover Measurements Glossary" help
.hover (opens in a new tab).to - Roofr blog, "How to Calculate Roof Waste Factor" roofr
.com (opens in a new tab) - Fine Homebuilding, "Don't Fall Short on Shingles: How to Estimate Materials for Roofing Projects" Fine Homebuilding (opens in a new tab)
- The manufacturer's installation instructions and bundle coverage for each shingle, starter and hip and ridge product installed (on the bundle wrapper or the manufacturer's website).
These guides document the scope of work a contractor performs. They aren't coverage or legal advice.