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When addenda land mid-bid: how to update a commercial roofing takeoff without starting over
Disclosure: Sharp Pencil sells commercial roofing takeoffs, so we have a stake in this topic.
This is a takeoff workflow, not contract advice. The bid documents decide how addenda are issued and acknowledged.
Last updated: 2026-10-29. Live facts checked on 2026-10-29.
What changes on a roofing takeoff when an addendum arrives?
Only the lines the addendum touches. Lock the baseline, find every change in the revised sheets, narrative items and spec sections, re-measure those lines, and record the before, after and difference for each one. Every quantity carries its source sheet and its basis.
Short answer
Save the takeoff you have as a baseline before you open the addendum. Read the whole addendum, not just the clouds, and list every roof, MEP and spec change. Re-measure only the lines those changes touch. Write each change as before, after and difference, with the sheet and addendum number. Acknowledge the addendum on the bid form, and put anything it leaves unclear on the Questions tab.
Lock the baseline before you open the addendum
Save a copy of the takeoff and the marked-up sheets as they stand, and name it with the set date. Without a baseline you cannot show what changed, and you cannot undo a wrong change. Keeping separate quantity sets is the same habit that helps when the roof plan and details disagree.
Log the addendum
Write down what arrived before you measure anything. Check whether an earlier addendum is missing, since a set that skips a number is not current. The roofing RFI register keeps that question with the others.
| Field | What to write |
|---|---|
| Addendum number and date | As printed on the addendum |
| Sheets reissued | Sheet number and revision mark |
| Narrative items | Item number and one line summary |
| Spec sections changed | Section number and title |
| Acknowledged on bid form | Yes or no, and where |
Find what changed: clouds, revision blocks, narrative and specs
- Clouds. Revision clouds and delta triangles are the usual way to mark changes, but they are not guaranteed to catch every one. Read the revision block and the narrative.
- Specs. An addendum can change the specs too, as a narrative item or a reissued section. Check both. See how to read Division 07 for a roofing takeoff.
- Other trades. Check the mechanical, plumbing, electrical and structural sheets too. A new curb, drain or unit changes roof lines. See which drawing sheets a roofing takeoff needs.
- Overlay. Overlay tools that lay a new sheet over the prior version can help you spot changes. Still read the revision block.
Re-measure only the lines that moved
Start from the change, then go to the lines it touches. Leave every other line as it was in the baseline.
| Change in the addendum | Lines it touches |
|---|---|
| New or moved rooftop unit | Curbs, flashing, walkway pads, penetrations |
| Added or moved drain | Drains, sumps, tapered insulation, crickets |
| System or membrane thickness change | Field membrane, flashings, adhesive or fasteners |
| Insulation R-value or cover board change | Insulation layers, cover board, edge and curb heights |
| Parapet or edge detail change | Coping, edge metal, base flashing |
| Steep slope area added or changed | Shingle or standing seam field, ridge, hip, valley, rake, eave, trim |
| Alternate added | A separate line list for the alternate |
See tapered insulation takeoff, edge metal takeoff, standing seam metal roof takeoff, asphalt shingle roof takeoff and bid alternates and unit prices.
Write the delta line by line
Each changed line gets the quantity before, the quantity after, the difference, and the sheet and addendum number. That is what lets a general contractor see why your number moved.
This is an example, not a real job, not a Sharp Pencil job, and not a price. The quantities are invented.
| Line | Before | After | Difference | Source |
|---|---|---|---|---|
| Curbs | 6 EA | 8 EA | +2 EA | M-101 rev 1, Addendum 2 |
| Walkway pads | 120 LF | 150 LF | +30 LF | R-101 rev 1, Addendum 2 |
| Cover board | 0 SF | 12,000 SF | +12,000 SF | 07 22 00 reissued, Addendum 2 |
Acknowledge the addendum and keep the questions open
- Many bid forms ask you to list the addenda you received. Fill it in.
- On federal sealed bids, FAR 52.214-3 lets you acknowledge an addendum by signing and returning it, by listing its number and date on the bid form, or by letter, fax or email where the solicitation allows.
- If the addendum leaves something unclear, it goes on the Questions tab, not into the number as a guess. See the roofing RFI register.
What an updated takeoff should hand back
Every quantity carries its source sheet and its basis.
Four files: START HERE, marked-up drawings PDF, Takeoff.xlsx with a Questions tab, and the material order list.
Pricing is optional. Send your cost data and we apply your prices to the quantities. Any line you have not priced comes back marked UNPRICED. See takeoff to material order.
FAQ
Do I have to redo the whole takeoff when an addendum comes out?
No. Save the takeoff you have as a baseline, find every change the addendum makes, and re-measure only the lines those changes touch.
Are the revision clouds enough to find every change?
No. Clouds and delta triangles usually mark changes, but nothing guarantees every change is clouded. Read the revision block, the narrative items and any reissued spec sections too.
Which sheets besides the roof plan should I check?
Check the mechanical, plumbing, electrical and structural sheets and the specs. A new unit, drain or detail on those sheets changes roof lines.
How do I show the general contractor what changed?
List each changed line with the quantity before, the quantity after, the difference, and the sheet and addendum number.
What if an addendum arrives after I have already priced?
Update the changed lines from the baseline and re-price only those lines. Acknowledge the addendum on the bid form either way.
What does Sharp Pencil send back on a 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. Usually within one business day. Delivered within 48 hours*.
*Clock starts once any questions we send you are answered.
Why send it to us
- We take off steep slope (standing seam, shingle) and commercial low slope (TPO, EPDM, PVC, mod bit, BUR) from the full set.
- Every quantity carries its source sheet and its basis.
- Four files: START HERE, marked-up drawings PDF, Takeoff.xlsx with a Questions tab, and the material order list.
- Pricing is optional. Send your cost data and we apply your prices to the quantities. Any line you have not priced comes back marked UNPRICED.
- Usually within one business day. Delivered within 48 hours*.
- A plan set you send us will never be used to compete with you, and plan sets are deleted whenever you ask.
- First takeoff free, one per contractor, on a job you're bidding or quoting.
- Have an addendum? Ask before you send it and you get the answer before anything is charged.
Residential is not our focus today, but ask if you have a job in mind.
*Clock starts once any questions we send you are answered.
Try it on a job you are bidding
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The Sharp Pencil team