Guide · Division 27 / 28 and 08 takeoff
How to take off a low-voltage bid from PDF plans
A working order for security, low-voltage and door hardware estimators: set up the plan set, confirm the scale on every sheet, count from the legend, build cable runs you can defend, reconcile the door schedule, and keep each number tied to the sheet it came from.
- AI-assisted
- Estimator-controlled
- Traceable to the plan
What should you set up before counting a single device?
Most takeoff time is lost looking for things, not counting them. Ten minutes spent organizing the set saves the hour you would otherwise spend flipping between sheets with the bid due tomorrow.
- Keep the set exactly as issued and work on a copy, named by issue date, so you can always show what the plans said when you priced them.
- Build a sheet index from the title blocks: sheet number, title, revision and date. It becomes your checklist and your revision log.
- Group the sheets you need: technology and security plans, riser and head-end details, electrical sheets for power and pathway, architectural plans, reflected ceiling plans and the door schedule.
- Pull the specification sections for your scope: Division 27 (Communications), Division 28 (Electronic Safety and Security) and the door hardware section of Division 08 (Openings). The spec decides cable types, owner-furnished items and testing.
- Write down what is missing on day one, such as a riser that is referenced but not included or a hardware set with no detail, and send the RFI before the question deadline rather than after it.
Why check the scale on every sheet, not once per set?
Every length you measure inherits the scale of the sheet it came from. One wrong scale does not produce one wrong number; it quietly corrupts every cable run on that sheet.
- Enlarged plans, details and key plans often sit at different scales from the floor plans, sometimes on the same sheet.
- A set printed or exported at half size still carries the full-size scale note, so a stated scale can be wrong by a factor of two.
- Calibrate against a dimension the drawing states, such as a column grid or a dimensioned wall, and compare it with the stated scale and the graphic scale bar.
- If they disagree, trust the written dimension, note the discrepancy on your sheet index and mention it in the bid assumptions.
- Sheets marked "not to scale" are for counting, not measuring. Take lengths for those areas from a scaled sheet that shows the same space.
How do you count devices from the legend without missing any?
Start from the legend, not from the floor plan. The legend tells you what exists on this project; the floor plan tells you where.
- Create one count line per legend symbol, using the legend’s own name, so a reviewer can match your list to the drawing without translating it.
- Watch the modifiers: letters or subscripts for ceiling versus wall mount, interior versus exterior, existing, relocated, future or "by others". Each modifier is its own line.
- Count sheet by sheet and mark each symbol as you count it, one color per symbol type, so a second pass shows what was missed at a glance.
- Expand "typical" notes. A room marked as typical of several others is a multiplier on your count, not a single room.
- Compare the plan count with the riser diagram and any device schedule. When they disagree, list the difference and send an RFI; do not average them.
- A symbol that is not in the legend is a question, not a guess. Put it on the RFI list and state in the bid how you priced it.
How should you take off cable runs and home runs?
A cable estimate built as a multiplier on device count is easy to produce and hard to defend. A run list measured on the drawing takes longer the first time and survives the questions.
- Locate the head-end, the telecom rooms and the panels first, and decide which area each one serves before measuring anything.
- Measure each home run along the likely pathway, down corridors and through accessible ceilings, not in a straight line across rooms.
- Add the vertical part of each run, from the ceiling or pathway down to the device, and the slack or service loops your spec or company standard requires.
- Take the cable type per device from the specification, because the cable to a camera, a reader, a door contact and a lock power supply are rarely the same.
- Keep the run list grouped by telecom room or panel. If a room moves in an addendum, you remeasure one group instead of the whole job.
- Write down who provides conduit, sleeves, J-hooks and firestopping. Pathway priced by both trades, or by neither, is a common change order.
How do you reconcile the door hardware schedule with the plans?
The door schedule and the floor plan are two sources for the same openings, and they are often drawn by different people at different times. Reconciling them is the takeoff for Division 08, and it matters to Division 28 wherever a door is electrified.
- Count the door tags on the plans and the rows in the schedule, then compare the two lists opening by opening, not just their totals.
- Openings on the plan with no schedule row, or schedule rows with no door on the plan, go on the RFI list with their numbers.
- Multiply hardware sets by the openings that use them, and check pairs against singles, since a pair carries hardware a single does not.
- Flag rated openings, because the hardware on them is constrained by the rating.
- For every electrified opening (electric strikes, electrified locks, request-to-exit devices, door position switches, power transfers), write down who furnishes, who installs and who wires it. That line between Division 08 and Division 28 is where hardware gets priced twice or not at all.
What changes when an addendum or a revised sheet arrives?
- Log each addendum against the sheet index: which sheets were reissued, the new revision and the date.
- Do not rely on revision clouds alone. Compare the reissued sheet with the one you counted, because not every change gets clouded.
- Check the scale again on reissued sheets; a reissue can come back at a different size.
- Update counts at the sheet level, so you can say exactly which lines moved and why.
- Keep the superseded sheets and your counts from them. If a question comes up after award, you will need both.
- Acknowledge every addendum on the bid form. A missed acknowledgement can disqualify a bid that was otherwise right.
What should you check before the bid goes out?
The last review is not a recount. It is a short list of checks that catch the errors a recount would also miss.
- Totals by sheet should add up to totals by device type. If they do not, a line was entered in one place and not the other.
- Spot-check the lines that carry the most money and the lines that changed in the last addendum.
- Have someone who did not do the takeoff check one sheet against your count, chosen at random.
- Compare plan counts with the riser diagrams and the door schedule one last time.
- Read the exclusions and assumptions as the general contractor will read them: are pathway, power, programming, owner-furnished devices and after-hours work all addressed?
- Confirm every open RFI is either answered or covered by a stated assumption.
How do you keep every count traceable to the sheet?
Traceability is what lets you answer "where did this number come from?" in under a minute, during bid review, after an addendum or in a change-order conversation months later.
- Every quantity line carries the sheet number, the revision and the legend symbol it came from.
- Nothing is typed into the estimate without a source. A number from an RFI answer or a phone call gets a note saying so.
- The marked-up sheets are saved with the estimate, so the count and the markup can be checked side by side.
- When the job is awarded, the project manager gets the same trail, not just a total.
Where does BidStream fit?
Everything above works with any takeoff tool, including a PDF viewer and a spreadsheet. BidStream is a pre-award estimating and proposal workflow built around the same discipline: AI-assisted, estimator-controlled and traceable to the plan. The AI proposes and the estimator approves; nothing is submitted on its own. When the proposal goes to the general contractor, the shared link shows sell price only, never cost or margin (verified as of October 2, 2026).
Common questions
Questions estimators ask about PDF takeoff
How do I handle a sheet marked "not to scale"?
Use it for counting, not for measuring. Take lengths for that area from a scaled sheet that shows the same space, and if none exists, state the assumption you priced in the bid.
Should the door schedule or the plan count win when they disagree?
Neither, until someone answers the question. Send an RFI with the opening numbers, price according to the document the spec says governs, and write that assumption into the bid so it is visible if it changes.
How do I estimate cable when the plans show no routing?
Measure along the pathway an installer would most likely use, through corridors and accessible ceilings, and add vertical drops and slack per the spec. State in the qualifications that lengths are based on assumed routing.
What should I do with symbols that are not in the legend?
Treat them as questions. List them by sheet, send an RFI, and say in the bid how you priced them, or that you excluded them, so the answer cannot surprise you after award.
Try it on the bid on your desk
Bring one bid you are pricing: 30 minutes, your plans, with a person from Vellarin.