A change order is not a new project estimate. It is a priced delta: the difference between what the contract documents showed and what the revised drawings now require. You send the change directive or variation request, the revised sheets, and the original drawings and specifications. We isolate the added, deleted, and resequenced work, take off only the affected quantities, and apply ZIP-code-adjusted material and labor pricing. The result is a line-by-line backup you can attach to a COR or CCO without rebuilding the full estimate.
- Deliverable
- Excel estimate + marked-up PDF plans
- Organized by
- CSI MasterFormat section
- Turnaround
- 24–48 hours for most projects
- Pricing
- ZIP-code-adjusted material and labor pricing
- Software
- Bluebeam Revu, PlanSwift, RSMeans data
We organize every change order by CSI MasterFormat division, matching the original estimate structure, and return Excel and PDF files with marked-up plan sets. Most change orders turn around in 24–48 hours. If you are pricing a design change, a differing site condition, or a field change order, we can also coordinate with your Construction Estimating Services team to keep the original and revised scopes aligned. For changes that affect the project schedule or cash flow, our Project Cost Control & Reporting service tracks the cumulative impact. We also flag when a change should be priced as a standalone estimate, such as a major scope addition that alters the project's square footage or structural system. In those cases, we may recommend our Preliminary & Conceptual Estimating service to establish a new baseline before pricing the delta. Our goal is to give you a defensible number that holds up to owner review, with every quantity traceable to a sheet and detail.
As an outsourced change order estimating company, we treat each request as a self-contained cost breakdown structure: added scope, deleted scope, and the markup percentage applied to each. We read the request for information (RFI) log and addendum set alongside the revised sheets, because a scope change is often defined in writing before it appears in the model. Where a BIM takeoff or on-screen takeoff in Bluebeam Revu or PlanSwift is faster than scaling paper, we use it, then reconcile the quantities against the original estimate. Every backup line carries a unit price, a material cost, and an equipment cost where applicable, so your team can defend the number line by line.
What our change order cost estimating covers
We price the delta, not the whole job. Every takeoff starts with a side-by-side review of the original and revised documents. We tag each line as added, deleted, or modified, then build the cost from the affected quantities only. That keeps the change order defensible and avoids double-counting work already in the base contract.
Concrete & Rebar Delta
Added or deleted concrete volume and rebar tonnage from revised foundation, slab, or grid dimensions.
CY · tonsPartition & Framing Changes
Added or relocated interior partition LF by wall type, including head, base, and jamb counts.
LF · EADoor & Window Revisions
Added or deleted door and window units by mark, with frames, hardware sets, and glazing.
EAElectrical Plan Changes
Added branch conduit LF and device counts from revised electrical plans or panel schedules.
LF · EAMechanical & Ductwork Delta
Added ductwork LF and diffuser counts from revised mechanical layouts or equipment schedules.
LF · EAFire Protection Adjustments
Added sprinkler head counts and main run LF from revised fire protection plans.
EA · LFStructural Steel Changes
Added structural steel tonnage and connection count from revised framing plans.
tons · EASitework & Roofing Deltas
Added excavation, backfill, and haul-off CY from revised site plans; added roofing area SF by assembly.
CY · SFWhat every change order estimating takeoff includes
- Added concrete volume and rebar tonnage from revised foundation or slab dimensions
- Deleted and re-poured slab-on-grade areas from a revised grid layout
- Added or relocated interior partition LF by wall type, with head, base, and jamb counts
- Added door and window units by mark, including frames, hardware sets, and glazing
- Added branch conduit LF and device counts from a revised electrical plan
- Added ductwork LF and diffuser counts from a revised mechanical layout
- Added sprinkler head counts and main run LF from a revised fire protection plan
- Added structural steel tonnage and connection count from revised framing
- Added excavation CY, backfill CY, and haul-off CY from a revised site plan
- Added roofing area SF by assembly type from a revised roof plan
- Labor hours for the added work at the applicable trade rate
- Equipment hours for added crane, excavator, or pump time
How we take off a construction change order
- Compare original and revised sheetsWe overlay the revised sheets on the original set in Bluebeam Revu, cloud every changed area, and assign a change tag. Each tag gets a CSI section number and a short description. This step catches deleted scope that is easy to miss when you are focused on additions. We also check for subtle changes like shifted grid lines or revised notes that affect multiple sheets.
- Isolate added, deleted, and modified workFor each clouded area, we take off only the affected quantities. If a revised grid shifts a column line, we measure the deleted footing and the added footing separately. That prevents double-counting and gives you a clean credit line for removed work. We also track modified items where the quantity changes but the unit remains the same.
- Apply ZIP-code-adjusted pricingWe price the delta using RSMeans data adjusted to the project ZIP code. Material and labor rates reflect the local market. For change-order material, we add small-quantity premiums and restock fees where the quantity falls below a full pallet or bundle. We also check for any agreed unit rates in the contract that override market pricing.
- Build the labor and equipment backupLabor hours come from the same crew rates used in the base estimate. We add hours for supervision, layout, and cleanup on the changed work. Equipment hours are logged for crane, excavator, or pump time, with mob and demob separated when the trade has already left the site. We also note any productivity adjustments for out-of-sequence work.
- Extend general conditions and markupWe calculate the general conditions impact for the added duration: supervision days, temporary facilities, and final cleanup. Then we apply the contract markup structure, stacking subcontractor markup under GC markup where the change order passes through multiple tiers. We also include bond and insurance costs on the increased contract value.
- Deliver the marked-up backupYou receive an Excel workbook and PDF organized by CSI division, with the clouded plan set attached. Each line shows quantity, unit, unit cost, and extended total. The summary page separates added cost, deleted credit, and net change so you can attach it directly to a COR or CCO. We also include a one-page summary for owner review.
What we need from you
- Change directiveThe written directive, variation request, or field order that defines the changed scope. This sets the boundary for what we price.
- Revised drawingsThe latest issued sheets with revision clouds or delta markers. We need the full sheet, not just the detail, to check adjacent scope.
- Original contract documentsThe drawings and specifications the base contract was priced from. We compare against these to isolate the delta.
- Specification sectionsThe spec sections covering the changed work, including any addenda or substitutions. This tells us the specified material and installation method.
- Contract markup termsYour overhead and profit tiers, subcontractor markup rules, and any agreed unit rates for force-account work.
- Schedule impact notesAny known resequencing, trade stacking, or out-of-sequence work that affects labor productivity on the change.
Sample change order quantity takeoff
A partial takeoff from a revised foundation plan. Each line is tagged to the change directive and priced with ZIP-code-adjusted rates.
| Section | Line item | Qty | Unit | Ref. |
|---|---|---|---|---|
| 03 30 00 | Spread footing 8' × 8' × 24", 4,000 psi | 6 | EA | S-101 |
| 03 30 00 | Slab-on-grade 6" thick, WWF 6×6-W2.9×W2.9 | 4,200 | SF | S-102 |
| 03 30 00 | Grade beam 18" × 24", #5 top and bottom | 320 | LF | S-103 |
| 03 30 00 | Column pier 30" × 30" × 4', #6 verticals | 4 | EA | S-104 |
| 03 30 00 | Equipment pad 10' × 12' × 12", 3,500 psi | 2 | EA | S-105 |
| 03 20 00 | Rebar, #5, including laps and dowels | 3.8 | TON | S-101 |
| 31 23 16 | Excavation for revised footings, 4' depth | 48 | CY | C-101 |
| 03 30 00 | Added concrete pump rental for placement | 1 | EA | S-101 |
| 03 30 00 | Formwork for added footings, 4' height | 320 | SF | S-101 |
| 03 30 00 | Curing compound for added slab area | 4,200 | SF | S-102 |
| 03 30 00 | Vapor barrier under added slab | 4,200 | SF | S-102 |
| 03 20 00 | Rebar dowels into existing footing | 24 | EA | S-101 |
Unit price, units, and how we measure them
Change order quantities are measured from the revised documents and cross-checked against the original takeoff. We use the same units as the base estimate so the delta drops straight into your cost report.
| Item | Unit | How it's measured |
|---|---|---|
| Added concrete volume | CY | Measured from revised footing, slab, or grade beam dimensions, with formwork and rebar separated |
| Added pipe or conduit | LF | Measured along the revised centerline, including fittings, hangers, and terminations |
| Added floor or wall finish | SF | Measured from the revised room finish schedule, with base and trim taken separately |
| Added fixtures or devices | EA | Counted by mark from the revised plan, including rough-in and trim-out labor |
| Added structural steel | TON | Measured from revised framing plans, with connection count and detail weight added |
| Added excavation or fill | CY | Measured from revised site plan contours, with haul-off and backfill separated |
| Force-account labor | HR | Tracked by trade and cost code for T&M change work, with equipment hours logged separately |
Worked example: pricing a revised slab-on-grade area
The dimensions below are illustrative. They show the step-by-step takeoff we run on a change order for a slab area that grew after a revised grid layout. The original contract showed a 60' × 40' slab. The revised sheet shows the same slab extended to 60' × 46'.
Step 1 — Establish the original quantity.
- Original area: 60.0 LF × 40.0 LF = 2,400 SF.
- Original volume at 6" thick: 2,400 SF × 0.50 ft = 1,200 CF.
- Convert to CY: 1,200 CF ÷ 27 = 44.4 CY.
Step 2 — Establish the revised quantity.
- Revised area: 60.0 LF × 46.0 LF = 2,760 SF.
- Revised volume: 2,760 SF × 0.50 ft = 1,380 CF.
- Convert to CY: 1,380 CF ÷ 27 = 51.1 CY.
Step 3 — Isolate the delta.
- Added area: 2,760 SF − 2,400 SF = 360 SF.
- Added volume: 51.1 CY − 44.4 CY = 6.7 CY.
Step 4 — Add waste as a separate line.
- Typical waste factor for slab concrete is 5%. We do not bury it in the quantity.
- Waste volume: 6.7 CY × 0.05 = 0.34 CY.
- Priced concrete: 6.7 CY + 0.34 CY = 7.04 CY.
Step 5 — Take off the dependent items.
- Vapor barrier: 360 SF (no waste, cut and lapped per spec).
- Welded wire fabric: 360 SF × 1.10 lap allowance = 396 SF.
- Curing compound: 360 SF.
- Formwork at the new edge: 60.0 LF × 0.50 ft = 30.0 SF.
- Dowels into the existing slab: 60.0 LF ÷ 2.0 ft spacing = 30 EA.
Step 6 — Price the delta.
- Concrete: 7.04 CY × local ZIP-adjusted unit cost.
- Vapor barrier: 360 SF × unit cost.
- WWF: 396 SF × unit cost.
- Curing: 360 SF × unit cost.
- Formwork: 30.0 SF × unit cost.
- Dowels: 30 EA × unit cost.
- Labor: place and finish crew hours for 360 SF, plus layout and cleanup.
- Equipment: pump or conveyor time for 7.04 CY.
Step 7 — Check for deleted scope.
- The revised grid removed two original dowel locations. We credit 2 EA and the associated labor.
- The original slab edge form at the 46' line is deleted: 60.0 LF × 0.50 ft = 30.0 SF credited.
Step 8 — General conditions and markup.
- If the added 360 SF extends the pour day by half a day, we add supervision and cleanup at the daily rate.
- Subcontractor markup is applied first, then GC markup on the pass-through amount, then bond and insurance on the net increase.
The final backup shows added cost, deleted credit, and net change on one summary line, with every quantity traceable to the revised sheet and the original contract drawing.
What drives change order pricing
Relative impact on a typical estimate for this trade, based on estimator judgment. Select a bar for details.
Resequencing
When a change pushes work out of sequence, labor productivity drops. A wall that was scheduled before the ceiling grid now has to be built after, which means working around hangers and diffusers. We add productivity loss hours where the change affects unchanged work. We compare the original schedule sequence to the revised sequence to quantify the impact.
Small-quantity material carries a premium. A change order for 3 doors costs more per door than the original 30-door package because the supplier adds a restock or small-order fee, and the installer loses the economy of a full run. We add these premiums as a separate line so they are visible and defensible.
When a change pushes work out of sequence, labor productivity drops. A wall that was scheduled before the ceiling grid now has to be built after, which means working around hangers and diffusers. We add productivity loss hours where the change affects unchanged work. We compare the original schedule sequence to the revised sequence to quantify the impact.
If a trade has already left the site, bringing them back costs more than keeping them. We add mob and demob, minimum crew hours, and any equipment re-delivery charges to the change order. We also check if the trade's contract includes a remobilization fee that should be applied.
Every day added to the schedule carries supervision, temporary facilities, and cleanup cost. We calculate the daily general conditions rate and multiply by the added duration shown on the revised schedule. We also include any additional temporary utilities or security required for the extended period.
On a pass-through change order, the subcontractor applies markup, then the GC applies markup on top. We model the contract's specific tiers so the total submitted cost matches what the owner will see. We also apply bond and insurance to the increased contract value using the rates stated in the contract.
Commodity materials like steel, copper, and lumber can fluctuate between the original bid and the change order date. We use current market pricing from RSMeans and note any escalation clauses in the contract. If the change order is priced months after the original bid, we may add an escalation factor.
Changes that affect permitted scope may require revised permits, re-inspections, or plan review fees. These costs come from the local building department, not the drawings. We flag them and note that you should confirm the local fee schedule with the authority having jurisdiction.
Common change order scope pricing gaps we catch
Most change orders lose money in the same places. These are the items that hide in the documents or get left out because they are not visible on the revised sheet.
- General conditions impact: added supervision, temporary power, and cleanup days for the extended duration. This hides in the schedule update, not the drawings. We calculate the daily rate and multiply by the added days.
- Labor productivity loss on unchanged work from resequencing and trade stacking. The revised plan shows the new layout but not the lost efficiency. We compare the original sequence to the revised sequence and add hours where trades now overlap.
- Restock, handling, and small-quantity material premiums. These appear on the supplier quote but are easy to drop when the change order is typed up. We add them as a separate line so they are visible and defensible.
- Remobilization and demobilization of trades that had already left the site. The change directive may not mention it, but the trade's schedule shows they were gone. We add mob and demob plus minimum crew hours.
- Disposal and dumpster fees for demolished or removed material. Deleted scope often generates waste that is not in the original contract. We add dumpster pulls and disposal fees to the credit side.
- Permit revision, re-inspection, and plan review fees where the change is permit-affecting. These come from the building department, not the drawings. We flag them and note that you should confirm the local fee schedule with the authority having jurisdiction.
- Bond and insurance cost on the increased contract value. This is a percentage of the net change and is often overlooked. We calculate it using the rates stated in the contract.
- Temporary protection and weather enclosure for work performed out of sequence. If a change forces work into a different season, we add temporary heat, hoarding, or dewatering as applicable. These costs are rarely shown on the revised drawings.
- Extended equipment rental for tools or machines left on site longer than planned. We log daily, weekly, and monthly rental rates and add the difference between the original and revised durations.
Pricing the material cost delta
A change order is priced on the difference between the original specified material and the substituted or added material. We compare four things on every line.
| Material comparison | Unit cost basis | Waste factor treatment | Labor and lead-time effect |
|---|---|---|---|
| Specified vs. substituted concrete mix | Compare 4,000 psi to 5,000 psi on a per-CY basis, including admixtures. | Waste stays at the typical 5% for slab; higher for formed walls. | Higher strength may require different cure time and finishing window. |
| Rebar grade change (#5 to #6) | Compare per-TON cost including laps and dowels. | Typical 3% for rebar cut and lap waste. | Larger bar diameter increases tying hours per ton. |
| Door and hardware substitution | Compare per-EA cost by mark, including frame and hardware set. | No waste factor; count by mark. | Lead time may drive a temporary door or a schedule extension. |
| Duct material change (sheet metal to spiral) | Compare per-LF cost by diameter, including fittings and hangers. | Typical 10% for sheet metal fittings; spiral is lower. | Spiral installs faster but requires different hanger spacing. |
| Sprinkler head substitution | Compare per-EA cost including escutcheon and trim. | No waste factor; count by head. | Different head type may change the required branch line spacing. |
| Roof assembly upgrade | Compare per-SF cost by assembly, including membrane, insulation, and cover board. | Typical 5% for membrane; insulation waste can run higher on cut-up roofs. | Additional layers add labor passes and may affect the roof warranty. |
| Paint system change | Compare per-SF cost by system, including primer and finish coats. | No waste factor; price by SF of surface. | Extra coat adds a full labor pass and dry time between coats. |
| Structural steel section change | Compare per-TON cost including connections and detail weight. | Typical 2% for steel; connections priced separately. | Heavier sections may require a larger crane and different erection sequence. |
Codes, standards, and specs that affect change order quantities
Model codes
Changes that touch permitted scope must be checked against the adopted model code family: IBC for commercial, IRC for residential, IECC for envelope and energy, NEC for electrical, IPC or UPC for plumbing, and NFPA 13 for sprinkler layout. A revised occupancy, a new wall that creates an exit access issue, or an added electrical load can change quantities beyond what the revised sheet shows. Confirm the adopted code edition and any local amendments with the local building department before you price the change, because the same drawing can require different work under different editions.
Industry standards
Standards govern how the changed work must be installed, which changes labor hours and material quantities. ACI 318 and ACI 301 affect concrete mix, curing, and tolerances. ASTM standards cover rebar, welded wire, and membrane materials. SMACNA governs duct construction and hanger spacing. GA-216 covers gypsum board application. NRCA details govern roof assembly and flashing. When a change substitutes a material, check the standard the original spec referenced; the substitute may require a different fastener, spacing, or substrate prep.
Specification sections
Every change order line should trace to a specification section. Division 01 sections 01 26 00, 01 26 13, and 01 26 16 define how the change is priced, what markup applies, and what backup is required. The changed work itself falls under its own division: Division 03 for concrete, Division 05 for steel, Division 08 for doors, Division 09 for finishes, Division 22 and 23 for plumbing and HVAC, Division 26 for electrical, Division 31 for earthwork. Read the section for submittals, testing, and warranty language, because those items carry cost that is not on the drawing.
Local amendments
Adopted code editions and amendments vary by state, county, and city. A jurisdiction may be on an older IBC edition with local amendments for seismic, wind, or energy requirements. Permit revision and re-inspection fees are set locally and are not on the drawings. Confirm the adopted edition, any amendments, and the current fee schedule with the local building department before you submit the change order. If the project is in a state we cover often, our regional pages for Texas, California, Florida, New York, and North Carolina estimating note common local practices, but the authority having jurisdiction is the final source.
Who uses our change order estimate for contractors
General contractors
You need a defensible backup to submit to the owner or architect. We price the delta and organize it by CSI division so it drops into your COR format. The marked-up plan set shows exactly what changed.
Subcontractors
You are asked to price a change before the GC has issued a formal directive. We take off the affected scope from the revised sheets and give you a number you can submit with confidence, including the small-quantity premiums that protect your margin.
Owners and developers
You receive a change order from the GC and need a second opinion before you approve it. We review the backup, check the quantities against the revised drawings, and flag missing credits or overstated labor.
Architects and engineers
You issue a revision and want to understand the cost impact before the owner asks. We price the change from your revised sheets and return a summary you can share with the project team.