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Commercial Re-Roof Takeoffs from Drawings: What Changes from New Construction
Disclosure: Sharp Pencil sells commercial roofing takeoffs, so we have a stake in this topic.
Last updated: 2026-10-28. Sources and sister pages checked on 2026-10-28.
A commercial re-roof takeoff still measures the new roof system from the plan set, but it also has to read existing conditions. Tear-off or recover, insulation against existing drains and curbs, edge metal reuse, hazard notes, and occupied phasing all change the lines. When the set is silent, put the gap on the Questions tab. Do not invent layers, asbestos status, or reuse. Sharp Pencil returns a four-file package with every quantity tied to its source sheet and its basis.
Re-roof vs new construction: the takeoff difference in one pass
New construction takeoffs assume a designed deck and a new assembly. Re-roof takeoffs from drawings still price the new work, and they also carry demolition, existing-assembly questions, reuse, and phasing that new work does not.
The table below is a working checklist for estimators. It is not a code manual and not a Sharp Pencil warranty rulebook. Soft practice notes that match our live roofing RFI register are labeled as such. Anything the set leaves open belongs on the Questions tab, not in a guessed quantity.
| Topic | New construction (typical) | Re-roof from drawings (typical) | If the set is silent |
|---|---|---|---|
| Starting point | New deck and new assembly on the drawings | Existing roof plus re-roof / existing-conditions documents | Ask which sheets govern existing vs new |
| Demolition / removal | Usually none for roofing field | Tear-off, partial tear-off, or recover prep as the set shows | Questions tab: tear-off vs recover? full vs partial? |
| Existing layers / cores | N/A | Core cuts, layer notes, or moisture notes when provided | Do not invent layer count. Questions tab / RFI |
| Insulation and taper | Designed taper and drains | Often must fit existing drains, curbs, heights, and any remaining insulation | See tapered insulation takeoff. Questions for missing slopes or cricket intent |
| Edge metal | New profiles from details | Reuse, overlay, or replace as noted | Questions: reuse vs replace by edge type |
| Flashings at walls / curbs | New | Match existing wall/curb conditions. May need removal of old base flashing | Questions when details do not say remove vs overlay |
| Hazards (asbestos and similar) | Rare on brand-new work | Survey status and handling notes when the set or bid docs speak | Never claim a building has or lacks asbestos. RFI / Questions only. See roofing RFI register. |
| Phasing / occupancy | Often open site | Occupied building, night/weekend, temporary weather protection, access/staging | Questions for schedule and access constraints that affect how you package quantities, not fake production rates |
| Steep slope (standing seam / shingle) when present | New field plus full linear list | Same linear discipline, plus tear-off of existing steep product when in scope | See standing seam and shingle sister pages. Take the full steep-slope linear list |
Commercial re-roof takeoffs cover low slope (TPO, EPDM, PVC, mod bit, BUR) and steep slope (standing seam and shingle). Do not treat a commercial re-roof as low-slope only.
Read the re-roof set before you measure (documents that change)
On a re-roof, the roof plan alone is even less enough than on new work. Existing conditions notes, demolition or preparation sheets, core or moisture exhibits, and the re-roofing preparation / roofing spec sections often decide quantities before you measure field membrane.
Re-roof habit before you measure field area:
- Find every sheet and note that names existing conditions, remaining assemblies, or "existing to remain."
- Find demolition / preparation for reroofing sheets or matching spec sections when they are in the bid set.
- Read core cut plans, core summaries, or moisture survey exhibits when the bid set includes them. Do not invent a layer count from a photo alone.
- Measure the new roof plan and any tapered insulation plan provided.
- Read details for edge, base flashing, curb, drain, and transitions against existing construction.
- Read structural notes that speak to deck type or overlay load. Do not invent structural capacity.
- Read roofing and preparation / selective demolition specs when present.
- If "existing" and "new" mix without a clear boundary, stop. Put the boundary on the Questions tab. Do not guess which areas are recover vs tear-off.
For the habit of reading sheets beyond the roof plan on any commercial takeoff, see the sheets a roofing takeoff has to read. Here we only call out re-roof-specific documents.
Tear-off vs recover: short fork
The set either tells you to remove existing roofing down toward the deck, to prepare the existing roof for a recover, or it leaves the path open. Your takeoff follows the documents. It does not invent the path.
Measure what is shown:
- Tear-off / removal area (SF) when the set dimensions or keys removal
- Partial tear-off zones when keyed
- Recover prep / recover board when the set calls for overlay on existing
- Disposal and selective deck repair only as the documents give quantities or unit lines. Otherwise, it goes on the Questions tab (do not invent tons or repair SF)
Silence rule: if the set never says tear-off or recover, measure the new system you can see and put "tear-off vs recover for [area]?" on the Questions tab. Do not assume recover to save demolition lines.
The quantity lines and RFIs for each path are in tear-off vs recover on a commercial roofing takeoff. Sharp Pencil already lists existing-conditions questions on the roofing RFI register, including asbestos survey status, number of existing layers (code often caps it), occupied tear-off, night/weekend limits, and access/staging. Prefer a Questions-tab line such as "confirm existing layer count and whether recover is allowed on this project" over inventing a layer-cap rule as our default.
When the bid is coating restoration instead of tear-off or recover membrane, see roof coating restoration takeoff.
When the re-roof is spray polyurethane foam, see SPF roof takeoff.
Insulation, taper, and drainage against what is already there
Re-roof insulation and taper often have to work with existing drains, curbs, parapet heights, and equipment that are not moving. That is different from a new roof where the designer sets the drainage story from scratch.
For taper method, board feet, and cricket/sump habits, use tapered insulation takeoff. Do not rewrite that method here.
Re-roof Questions tab prompts (examples, not a universal list):
- Existing insulation to remain?
- New cover board over existing?
- Taper to existing drain locations?
- Parapet or curb height conflict with new insulation thickness?
- Cricket intent where the set shows slope arrows but no cricket plan?
When the re-roof is low slope, take off the full low-slope package (field, taper when shown, edge, penetrations, flashings). When it includes steep slope, take off standing seam or shingle with the full linear list: ridge, hip, valley, dead valley, rake, eave, endwall and sidewall flashing, transitions, starter, drip edge and gutters. See standing seam metal roof takeoff and asphalt shingle roof takeoff. If one area keeps an existing system and another is replaced, see mixed-system commercial roof takeoff for the transition line.
Edge metal and flashings: reuse, overlay, or replace
New construction edge metal is usually new profiles from the details. Re-roof sets often say reuse, overlay, or replace by condition. Your takeoff must follow that split by edge type, not one blended "perimeter" line.
Separate lines when the set separates them: coping, gravel stop, fascia, drip edge, counterflashing, and similar profiles.
Reuse: only when the documents say reuse or "existing to remain." If they say "replace as required" without a quantity, put it on the Questions tab. Do not invent a reuse percent.
We do not cover ES-1 edge design or manufacturer edge approvals here. If ES-1 or edge design shows up as a bid risk, note it as a question for the design team or manufacturer, then keep measuring what the details show.
Wall base flashing and curb flashing: note removal of existing base flashing when the preparation or roofing details require it. Otherwise Questions tab.
Hazards and asbestos: RFI language only (never a building claim)
A takeoff does not declare that a roof does or does not contain asbestos or other hazardous materials. It records what the bid documents say, and it puts missing survey status on the Questions tab / RFI register.
Match the live roofing RFI register existing-conditions block: asbestos survey status, number of existing layers (code often caps it), whether tear-off can happen in occupied conditions, night work or weekend restrictions, and roof access and staging.
Hard rules for hazards:
- Never claim a sample building has ACM.
- Never invent abatement SF, disposal rules, or EPA notification steps as Sharp Pencil instructions.
- Never cite a code section number as Sharp Pencil law.
- Phrase these as questions the estimator should send, not as legal advice.
Occupied building phasing and access (what belongs on the takeoff vs the bid)
Occupied re-roofs often constrain how much roof can be open, when work can happen, and how material gets up. Some of that is schedule and means-and-methods (bid), not a measured quantity. Still, the set sometimes keys phased areas, temporary protection, or access limits that change how you package the takeoff.
Keep measured quantities honest: phased area keys when shown, and temporary roofing or night seal products only when specified and measurable.
Put on the Questions tab when the set is silent: max open area per day, night/weekend limits, crane vs conveyor access, interior protection ownership, and HVAC shutdown responsibility.
Do not invent productivity rates, crew sizes, or dollar premiums for occupied work. For general timing context on commercial takeoffs, see how long a commercial roof takeoff takes. That guide covers hour ranges. We do not invent a re-roof hour table here.
Common misses when a re-roof is bid like new construction
- Measuring only the new membrane and skipping tear-off / recover prep
- Assuming recover to avoid demolition lines when the set never says recover
- Ignoring core cut or existing-conditions exhibits included in the bid set
- Blending reuse and replace edge metal into one perimeter LF
- Guessing asbestos status or layer count instead of RFI / Questions tab
- Pricing new taper as if drains and curbs were free to redesign
- Skipping steep-slope linear items when the re-roof includes standing seam or shingle
- Treating occupied phasing notes as optional reading
Worked example: one made-up re-roof wing (not a real job)
This example is invented. It is not a real building, not a Sharp Pencil job, and not a price. Use it only to see how lines and Questions split on a re-roof set.
Assumptions (invented):
- One rectangular low-slope wing, 120 ft by 80 ft
- Re-roof plan A-401 shows new TPO field over the full wing
- Demolition note on A-400 keys full tear-off of the existing roofing on that wing
- Existing roof drains to remain (four drains shown)
- Spec calls new cover board plus new insulation over the prepared deck
- Coping note: replace
- Gravel stop note: "reuse where sound" with no quantity
- No asbestos survey sheet in the bid set
- No steep-slope canopy on this wing
| Line | Quantity / status | Source sheet and basis |
|---|---|---|
| New TPO field | 9,600 SF | A-401, 120 ft × 80 ft plan rectangle |
| Tear-off / removal (same wing) | 9,600 SF | A-400 demolition key, full wing keyed for tear-off |
| New cover board | 9,600 SF | Spec Division 07 + A-401 field area |
| New insulation (flat, as specified) | 9,600 SF | Spec Division 07 + A-401 field area |
| Coping replace | 400 LF | A-401 / edge detail, perimeter 2×(120+80) |
| Gravel stop reuse quantity | On Questions tab | Note says "reuse where sound", but no measured reuse LF on set |
| Asbestos survey status | On Questions tab | Not in bid set. Never invent ACM presence or absence |
| Tear-off vs recover | Measured as tear-off | A-400 keys tear-off. If a future addendum changed path, re-measure |
No dollar totals. No waste percent invented. No ACM claim. No code section numbers. If this wing included a steep-slope entry canopy, field plus linear items would follow the standing seam or shingle sister pages.
FAQ
How is a commercial re-roof takeoff different from a new construction takeoff?
A new construction takeoff starts from a designed deck and a new assembly. A commercial re-roof takeoff from drawings still measures the new roof system, and it also has to read existing conditions, follow tear-off or recover notes, split edge reuse vs replace, and carry hazard and phasing questions the new-work set usually does not have. When the set is silent, put the gap on the Questions tab instead of guessing.
What drawings matter most on a commercial re-roof takeoff?
Existing-conditions plans or notes, demolition or preparation-for-reroofing sheets, core or moisture exhibits when provided, the new roof plan and any taper plan, edge and flashing details against existing construction, structural notes that speak to deck or overlay, and the roofing / preparation specs. The roof plan alone is not enough. See the sheets a roofing takeoff has to read.
Do I take off tear-off and recover the same way?
No. Measure what the set shows: tear-off SF, partial tear-off zones, or recover prep / recover board. If the set never names the path, measure the new system you can see and put tear-off vs recover on the Questions tab. Do not assume recover to skip demolition lines. For the line-by-line method on both paths, see tear-off vs recover on a commercial roofing takeoff. For existing-conditions questions, use the roofing RFI register.
What should go on the Questions tab before I price a re-roof?
Anything the documents leave open goes there. That includes tear-off vs recover by area, existing layer count and whether recover is allowed, asbestos survey status, and edge reuse vs replace by profile. It also includes insulation or taper conflicts with existing drains and curbs, limits on occupied open area, night/weekend work, or access, and selective deck repair when no quantity is given. Do not invent layers, ACM status, reuse percents, or occupied productivity rates.
What does Sharp Pencil send back on a commercial re-roof takeoff?
Four files: START HERE, marked-up drawings PDF, Takeoff.xlsx with a Questions tab, and the material order list. Every quantity carries its source sheet and its basis. Open re-roof items stay on the Questions tab. First takeoff free, one per contractor, on a job you're bidding or quoting. After that, $395 per new set of drawings, or monthly plans. Usually within one business day. Delivered within 48 hours*.
*Clock starts once any questions we send you are answered. Preview the roofing takeoff sample and what a takeoff costs.
Edge reuse vs replace by profile on a re-roof set? See edge metal roof takeoff.
Why send your takeoffs to Sharp Pencil
The expensive miss on a re-roof bid is not only the new membrane. It is tear-off vs recover, existing conditions, edge reuse, and hazard or phasing gaps that never made it onto the Questions tab.
- Usually within one business day. Delivered within 48 hours*. A takeoff stuck in a week-long queue does you no good when the bid is due sooner.
- Every page gets read. Send the full set: architectural, structural, mechanical, plumbing, existing-conditions exhibits, and the spec book if you have it.
- Every quantity names its sheet. Every quantity carries its source sheet and its basis, so you can check it against the drawings.
- Questions instead of guesses. If the set leaves something open, it goes on the Questions tab in Takeoff.xlsx, not into the number as a guess.
- Checked before it goes out. Every paid takeoff is checked before delivery.
- Four files, one package. START HERE, marked-up drawings PDF, Takeoff.xlsx with a Questions tab, and the material order list.
- Your plans stay yours. A plan set you send us will never be used to compete with you, and plan sets are deleted whenever you ask. See what happens to your plans.
- First takeoff free, one per contractor, on a job you're bidding or quoting. After that, $395 per new set of drawings, or monthly plans. See what a takeoff costs and how it works.
Commercial roofing takeoffs for low-slope (TPO, EPDM, PVC, mod bit and BUR), standing seam and shingle roofs. Residential is not our focus today, but ask if you have a job in mind. See our commercial roofing takeoff services and where every number comes from.
Get your first takeoff free · See full pricing and plan terms · Or email [email protected]
*Clock starts once any questions we send you are answered.
The Sharp Pencil team
Get your first takeoff free · See full pricing and plan terms · Read how we handle your data · Or email [email protected]
Sources
- Sharp Pencil RFI register (existing conditions on re-roofs): /roofing-rfi-register (checked 2026-10-28)
- Sharp Pencil drawing sheets: /roofing-takeoff-drawing-sheets (checked 2026-10-28)
- Sharp Pencil tapered insulation: /tapered-insulation-takeoff (checked 2026-10-28)
- Sharp Pencil mixed-system: /mixed-system-commercial-roof-takeoff (checked 2026-10-28)
- Sharp Pencil roof coating restoration: /roof-coating-restoration-takeoff (checked 2026-10-28)
- Sharp Pencil SPF roof: /spf-roof-takeoff (checked 2026-10-28)
- Sharp Pencil timing: /how-long-does-a-commercial-roof-takeoff-take (checked 2026-10-28)
- Sharp Pencil cost: /commercial-roofing-takeoff-cost (checked 2026-10-28)
- Sharp Pencil sample: /roofing-takeoff-sample (checked 2026-10-28)
- Sharp Pencil standing seam: /standing-seam-metal-roof-takeoff (checked 2026-10-28)
- Sharp Pencil asphalt shingle: /asphalt-shingle-roof-takeoff (checked 2026-10-28)
- Sharp Pencil services, how it works, your-data, upload, pricing, accuracy, homepage four-file / free / $395 / turnaround / steep-slope scope (checked 2026-10-28)