The median electrical or mechanical contract in our set of 1,096 federal awards closed 1.8% above its award price. The dollars closed 9.5% above it. That gap between the typical contract and the typical dollar is the whole story of change orders: most jobs finish close to the bid, and a quarter of them finish more than 10% over, and the quarter carries the money. We pulled 2,439 priced change orders from two kinds of public record: 2,417 modifications to federal construction contracts coded to electrical (NAICS 238210) and plumbing, heating and air-conditioning (238220) contractors on USAspending.gov, and 22 change orders that city councils and utility boards in Fort Worth, Riverside, Kansas City, Sacramento, El Paso and San Antonio approved with the memo attached. This piece sizes the change-order load by project type, size and buyer, sorts the reasons that recur, names the five line items that always grow, checks billed hours against a published labor unit, and ends with the contract language and the contractor ratio table.
The Open Factory Public Bid-Tab Price Book holds the dataset: for every contract the award, the contractor, each change order’s date, value and text, and the URL of the public record.
Source: Open Factory Public Bid-Tab Price Book (compiled from USAspending.gov contract modifications, NAICS 238210 and 238220, and city council and utility board records; as of March 2026)
Of the 1,096 contracts, 383 (35%) closed with no priced change order, 125 finished 0 to 2% over, 148 finished 2 to 5% over, 126 finished 5 to 10% over, 131 finished 10 to 20% over, 106 finished 20 to 50% over, 33 more than doubled or came close to it, and 44 finished below award after deductive changes.
What the 2,439 Records Are
The federal rows come from the USAspending API: every definitive contract (award type D) awarded in fiscal years 2019 to 2024 with a non-change-order value between $1M and $60M, coded to NAICS 238210 or 238220. That returned 1,162 awards, of which 1,096 fit the value window; for each we pulled every modification. A change order is a modification whose FPDS action type is CHANGE ORDER, SUPPLEMENTAL AGREEMENT FOR WORK WITHIN SCOPE, DEFINITIZE CHANGE ORDER or ADDITIONAL WORK, with a non-zero dollar value, dated on or before March 4, 2026, whose text is not a close-out, de-obligation or option exercise. Deducts count. Method and keyword rules: research/notes.md.
The set covers 51 federal buyers and 486 contractors in 54 states and territories. Four buyers dominate: the Army (263 contracts), Veterans Affairs (242), the Air Force (150) and the Navy (74), then GSA’s Public Buildings Service (58), the Bureau of Prisons (45) and the FAA (33). Pricing is almost all firm fixed price: 1,088 of 1,096 contracts, with four time-and-materials and two cost-no-fee awards. On a fixed-price job every dollar in this file is a negotiated modification, not an hours ticket.
The municipal rows are the opposite kind of evidence: few, each with a paragraph explaining why. Riverside’s Board of Public Utilities has to approve any change order that takes a contract past 10% of its original price under Purchasing Resolution 24101, Section 1104, so every overrun above 10% gets a memo. Fort Worth’s council communications list each prior change order with its cause; El Paso’s coversheet has checkboxes for differing site condition, user request, design error and quantity adjustment, and prints the contractor’s first proposal against the negotiated figure. Those 13 contracts carry 22 change orders and every reason category we use.
The Median Is 1.8%. The Dollars Are 9.5%
The 1,096 federal contracts had a combined non-change-order value of $3.54B and collected $338.0M of net change orders: $352.9M additive across 2,263 modifications and $15.0M deductive across 175. The median contract’s net change was 1.8% of award; the mean was 8.8%; the 75th percentile contract sat at 9.9% and the 90th at 23.7%. Among the 715 contracts that had at least one priced change order, the median net change was 6.6% and the median count was two. The median single change order was $45,619, or 1.37% of its contract.
The electrical trade runs lighter than the mechanical trade on every measure. The 445 NAICS 238210 contracts (base $1.49B) carried a median 1.4% and a dollar-weighted 7.4% ($109.4M), and 22% of them ended more than 10% over. The 651 mechanical contracts (base $2.06B) carried a median 2.3% and a dollar-weighted 11.1% ($228.6M), and 26% ended more than 10% over. The median electrical change order was $41,644. A 10% contingency covers the 75th percentile electrical contract with room; on a mechanical package it covers the 75th percentile exactly.
Source: Open Factory Public Bid-Tab Price Book
Contracts of $1M to $3M (n=728) had a median net change of 1.0%, a dollar-weighted 8.3% and 1.45 change orders each, with a median change order of $38,065; $3M to $10M (n=332) had a median 3.7%, dollar-weighted 10.6%, 3.2 change orders and a median change order of $45,619; $10M to $60M (n=36) had a median 3.9%, dollar-weighted 9.5%, 8.3 change orders and a median change order of $84,084. Size buys more change orders, not a bigger share. The 9.5% dollar-weighted figure, not the 1.8% median, is the change-order allowance to put against the electrical and mechanical lines of the Datacenter MEP Cost Table: it is the number the money follows.
Change Orders by Project Type and Size
We classified each contract from its award description into seven types. Generator and backup-power jobs carried the highest median, HVAC the second, and lighting the lowest.
Source: Open Factory Public Bid-Tab Price Book
Generator and backup power contracts (n=39) had a median net change of 2.6% and a 75th percentile of 9.7%; HVAC and mechanical (n=577) 2.3% and 10.7%; substation and MV distribution (n=69) 2.2% and 9.5%; fire alarm, security and communications (n=91) 1.6% and 11.4%; controls and SCADA (n=69) 1.6% and 10.6%, with 72.5% of them carrying at least one change order, the highest share of any type; general electrical renovation (n=197) 1.4% and 9.0%; lighting (n=54) 0.8% and 4.3%. Dollar-weighted, fire alarm and security ran 11.5%, HVAC 10.9%, controls 10.8%, general electrical 7.8%, substation 6.9%, generators 5.0% and lighting 4.7%.
Lighting is the one electrical package where a 5% contingency is enough: the scope is countable from the drawings. Controls and SCADA is the package where a change order is almost certain even when small: seven in ten of those contracts were modified, because integration scope (points lists, graphics, network drops, the PLC another project did not finish) is written after award. Fort Worth’s SCADA replacement is the type specimen: Change Order 1, $125,732.39 on an $8,233,836 contract, for “one additional Category, a PLC that was not part of the original scope of work … from a project that was not complete at the time this project was bid.”
Buyer matters as much as type. Among agencies with 15 or more contracts, the National Institutes of Health carried a median 9.9% (n=15, 80% of contracts modified, 20.2% dollar-weighted), the FAA 6.5% (n=33, 88% modified), the Agricultural Research Service 4.4%, Veterans Affairs 3.7% (n=242, 77% modified, 10.9% dollar-weighted), the National Park Service 3.0%, GSA’s Public Buildings Service 2.4% (11.2% dollar-weighted), the Bureau of Prisons 1.5% and the Army 1.1% (n=263, 62% modified, but 10.1% dollar-weighted). State, the Air Force (n=150), the Navy (n=74) and Customs and Border Protection had a median of zero; fewer than 55% of their contracts were modified at all.
Source: Open Factory Public Bid-Tab Price Book
The buyer table says the owner’s habits set the rate before the contractor arrives. NIH’s central utility plant chiller repairs went from $1,766,165 to $4,016,661 (127%) through in-scope supplemental agreements; the Air Force’s 150 contracts ran 4.6% dollar-weighted with a median of zero. Same trades, often the same contractors, different owners.
The single-contract extremes are owner stories more than contractor stories. SES Electrical LLC’s Fort Bliss hospital renovation design-build went from $2,305,533 to $8,426,580 (265%) through 17 modifications; Precision Mechanical’s Launch Complex 39B environmental control system went from $7,368,751 to $19,158,198 (160%) through 31; Midlands Mechanical’s Denver Mint air handler replacement added a $4,339,862 “Phase II” to a $3,883,087 contract in one modification. Read the count and the text before the ratio: 31 supplemental agreements on a launch-pad HVAC job is a design that was not finished at award, and the price at the end is the price the design should have carried at the start.
Who Writes the Reason Down
Of 2,439 change orders, 1,693 (69%) carry no reason at all: the modification text repeats the project title, or reads “MOD 3”, or names a CLIN. That is a finding about federal contracting officers, not about contractors, and it is why the municipal records matter out of proportion to their count. The federal changes clause, FAR 52.243-4, requires the contractor to “assert its right to an adjustment … within 30 days” of a written change order and promises an “equitable adjustment”; it does not require the reason to be recorded or say how the adjustment is priced. Where a reason is written, the distribution is stable across buyers.
Source: Open Factory Public Bid-Tab Price Book
Of the 746 change orders with a stated reason, 461 (61.8%) were the owner adding or changing scope ($71.5M additive), 93 (12.5%) were unforeseen or differing site conditions ($18.7M), 68 (9.1%) were design errors, omissions or RFI resolutions ($6.6M), 60 (8.0%) were delay, suspension or time-related costs ($9.1M), 42 (5.6%) were deductive credits (net -$1.5M), 11 (1.5%) were code or authority-having-jurisdiction changes, 9 (1.2%) were price escalation and 2 were utility company relocations. The categories are ours (build_dataset.py); the text is the government’s.
Escalation is smaller than the trade press would suggest. Nine federal modifications in seven years said “price increase” in so many words, the largest a $113,840.55 increase (7.9%) on a VA access-control contract in April 2022 and a $23,983.30 increase (0.7%) on Sturgeon Electric’s Denver Federal Center substation transformer in July 2023. Firm-fixed-price federal work has no escalation clause, so the copper and steel moves of 2021 to 2025 landed inside the bid or the contractor’s margin. The municipal record shows where they landed when the contract allowed it: Riverside’s Daikin chiller ordered in April 2021 at $173,845 was repriced to $247,833 (42.6%) in November 2022 because the vendor “was unable to place the order with the Daikin factory at the previously quoted … pricing”, and Riverside’s 69 kV steel poles carried an estimated $222,704 (33.4%) after the fabrication date slipped from June 2021 to January 2022 “which has subjected RPU to rising steel prices”. The Copper and Wire Price Sheet exists so that an escalation clause names an index and a base date instead of a vendor letter.
The Reasons That Recur
Unforeseen conditions are 12.5% of stated reasons and 17% of the stated additive dollars, and the text tells you what they are. RHI LLC’s steam condensate replacement at the Tomah VA Medical Center took a $1,714,015 modification (42.4% of a $4.04M contract) in September 2022 for “extra asbestos abatement, plywood and plastic safety barriers”, after a $561,854 modification three months earlier for “corrections for design oversight, unknown existing conditions”. Brice Builders’ Barter Island job took $1,675,512.80 (23.0%) for “differing site conditions” in December 2021, sixteen months after a $921,278 descope. C.D. Whitfield’s chiller renovation at the DFAS Supply Center in Columbus took $800,000 and then $858,541 (32.8% and 35.2% of a $2.44M contract) in 2023 and 2024 for “replace duct and mold mitigation”. Asbestos, mold and what is behind the wall are the unforeseen conditions of renovation; on greenfield work it is soil and utilities. The governing clause is FAR 52.236-2: “subsurface or latent physical conditions at the site which differ materially from those indicated in this contract”, with notice required “before the conditions are disturbed”.
Design errors and omissions are 9.1% of stated reasons and the category owners most under-count, because the text rarely says “error”. It says “correct quantity of CLIN 1001”, as in Lanotte Refrigeration’s $446,548 modification (43.4%) for the Agricultural Research Service, or “modification to address RFIs 06, 16, 17 and 18”, as in B2 Constructors’ $257,333 (9.7%) for a VA energy management system. Riverside’s version is the clearest on the record: on the Limestone Drive cable replacement, a cap-and-grind step on slurry-seal streets “had not been accounted for during the design phase and was not included in the scope of work when the project was bid. This oversight resulted in a doubling of the unit price for cap-and-grind work”, and with 80 tons of asphalt for pavement delamination the change order came to $115,484 on a $704,840 contract (16.4%).
Owner scope is the majority and it is not a scandal. Fort Worth’s athletic field lighting came in $498,690 under budget and the city spent $368,000 of the savings on a seventh ball field with Change Order 1 (20.1%). Kansas City’s Richards Road electrical upgrade added a new S&C switch with micro switching to feed two hangar transformers for $308,174 (25.4% on a $1,214,435 contract) in November 2022, and the form notes “current lead time for this equipment is 42 to 44 weeks, contract time will be increased at a later date”. Fort Worth Water’s $23.1M generator project relocated a diesel generator from one fence line to another, rerouted the duct banks, and replaced an RTU and PLC for SCADA compatibility in one $221,671.33 change order. These are decisions priced after award; the buyer’s only question is whether they were priced at bid rates or change-order rates.
The Five Line Items That Always Grow
We tagged each change order with the line item its text names. Across the whole set the additive dollars go to HVAC equipment and piping first ($56.0M across 346 change orders), then controls, SCADA and PLC ($13.0M, 107), panels, switchgear and transformers ($9.8M, 112), fire alarm, security and communications ($9.8M, 64), conduit, duct bank and raceway ($8.8M, 61), lighting ($8.3M, 52), civil and finishes ($6.0M, 58), feeders, wire and cable ($5.5M, 49), generators and backup power ($5.1M, 42), time and general conditions ($4.1M, 34) and hazmat abatement ($2.6M, 12).
Source: Open Factory Public Bid-Tab Price Book
Restrict to the 853 electrical-contractor rows and the ranking becomes the list a plant buyer should carry into every electrical negotiation. Of the 334 additive electrical change orders that name a line item, panels, switchgear and transformers appear in 70 ($5.64M, 16.9% of the named dollars), feeders, wire and cable in 37 ($4.84M, 14.5%), fire alarm, security and communications in 50 ($4.63M, 13.9%), generators, ATS and UPS in 33 ($4.58M, 13.7%) and conduit, duct bank and raceway in 39 ($2.66M, 8.0%). Those five items are 229 of the 334 named electrical change orders and 67% of the named electrical dollars. Lighting, the item every owner expects to grow, is 20 and $2.59M.
Each of the five grows for a reason that can be written into the bid. Switchgear and panels grow because the one-line is redrawn after award: M.C. Dean’s Buckley plant recapitalization carries a $146,849.44 modification titled “XFMR AND PANEL ONE-LINE UPDATES” and a $36,170 one for “PANEL UPSIZING”. Feeders grow because sizes and set counts change: the same contract has a $100,562.50 credit for “MV FEEDER CABLES SIZES & SETS” and a $59,017 add for a “BUILDING 201 NEUTRAL FEEDER”. Fire alarm and low-voltage grow because the AHJ reads the drawings last: Broadway Electric’s Cleveland VAMC fire alarm upgrade lists “ALT CONDUIT RUN TO COMPLY WITH NFPA” among eight modifications. Generators grow because the paralleling and fuel scope is discovered at submittal: DLJ Management’s $582,943 modification (15.9%) to “replace additional switches” added 42 calendar days. Conduit grows because quantities are estimated from plan and paid from the field: Riverside’s Doty Bros. job found an unmarked cable-television conduit at the new vault, and El Paso’s Change Order 13 added 9,515 linear feet of conductor and 1,495 feet of 3-inch PVC and bores when El Paso Electric set its service points “far away from the anticipated location” at eight stations. Reading a Switchgear Quote walks the one-line clauses that decide the first of the five; the 2 MW plant service upgrade shows the utility service point deciding the fifth.
When the Change Orders Land
Change orders are not front-loaded. Of the $352.9M of additive federal change orders, 8.0% were signed in the first six months after award, 19.6% in months 6 to 12, 19.1% in months 12 to 18, 17.8% in months 18 to 24, 18.6% in months 24 to 36, 9.9% in months 36 to 48 and 6.9% (60 change orders, $24.3M) more than four years after award.
Source: Open Factory Public Bid-Tab Price Book
The cumulative line crosses 50% in the 12 to 18 month band and 83% at 36 months, so the contingency has to survive past substantial completion: what arrives after month 36 is delay cost, suspension lifts and the second year of off-site storage. Greenland Enterprises’ $774,560.75 modification (8.4%) in December 2024 is titled “delay costs associated with modification nos. P00032 and P00034”; Spees-Hernandez JV’s $999,439 (14.2%) in January 2026 is “2nd year of offsite storage required due to current work suspension”. Equipment lead time turns a scope change into a time change; the Lead-Time Monitor’s published figures for switchgear and generators belong in the schedule clause before award, and the Lead-Time-Adjusted Schedule puts them on a calendar.
Thirteen Contracts With the Memo Attached
The council and board records are few, and they are the only place the reason, the markup and the contractor’s first price appear together.
Source: Open Factory Public Bid-Tab Price Book, Fort Worth, Riverside, Kansas City, Sacramento, El Paso and San Antonio Legistar records
| Buyer | Contractor | Original | Change orders | Net change | % of award | Recorded reason |
|---|---|---|---|---|---|---|
| Riverside General Services | NSWC Mechanical Service | $173,845 | 1 | $73,988 | 42.6% | Factory repricing, steel and copper |
| San Antonio via J3 Company | SAECO Electric & Utility | $331,403 | 1 | $126,531 | 38.2% | CPS duct bank redesigned 4-way to 9-way |
| Riverside Public Utilities | Wireless Structures Consulting | $666,680 | 1 | $222,704 | 33.4% | Design changes, steel escalation (estimate) |
| Kansas City Aviation | Citadel Electric Group | $1,214,435 | 2 | $322,494 | 26.6% | Owner-added S&C switch, 42 to 44 week lead time |
| Sacramento Public Works | David Engineering Construction | $223,000 | 2 | $57,731 | 25.9% | Paving added; ADA van access |
| Fort Worth Park and Recreation | Groves Electrical Service | $1,832,140 | 1 | $368,000 | 20.1% | Seventh ball field funded from bid savings |
| Riverside Public Utilities | Asplundh Construction | $704,840 | 1 | $115,484 | 16.4% | Cap-and-grind omitted from design; delamination |
| Riverside Public Utilities | Doty Bros. Equipment | $118,780 | 2 | $13,043 | 11.0% | Paving discrepancy; unmarked CATV conduit |
| Riverside General Services | Stilwell Construction | $378,707 | 2 | $41,421 | 10.9% | Structural redesign at plan check; ADA drawings |
| El Paso Capital Improvements | Venegas (VEMAC) | $19,583,784 | 13 | $462,323 | 2.4% | CO 13: El Paso Electric moved service points |
| Fort Worth Water | Red Group | $8,233,836 | 1 | $125,732 | 1.5% | PLC from an unfinished adjacent project |
| Fort Worth Water | ACME Electric (Winston Electric) | $23,119,632 | 3 | $321,399 | 1.4% | Generator relocation, fence, insulation |
| Fort Worth Water | ACME Electric (Winston Electric) | $8,647,846 | 3 | $104,941 | 1.2% | Pump starters, cables, deleted control panels |
CSV: data/06-municipal-cases.csv
The 13 contracts split the same way the federal set does: the three above 30% are equipment-heavy contracts under $700,000 where the change was escalation or a redesign, and the four below 2.5% are contracts above $8M with a full-time inspector and a memo for every change. The El Paso coversheet is the model form. It records that the contractor’s original proposal on new items was $31,656.69, that the negotiated amount was $134,309.49 after quantities were reconciled to the field, that an independent cost estimate was prepared, and that pricing used “unit bid prices previously approved” where they existed ($4.04 per linear foot for #4 AWG, $11.76 for #3/0, $10,077.94 per overhead service point) and negotiated unit prices where they did not ($6.24 for #2, $8.90 for #2/0, $10.48 for #4/0, $19.35 per foot of 3-inch PVC, $32.57 per foot bored). A unit-price schedule turns a change order into arithmetic.
Labor Units Against Billed Hours
Every change order on a fixed-price contract is priced as if it were time and materials: hours times rate plus material plus markup, and the hours are the argument. Contractors price them from a labor-unit manual; the one contracts reference is NECA’s Manual of Labor Units, which NECA sells and does not publish. The public proxy is Craftsman’s National Electrical Estimator, whose 2025 preview pages print the units and the method: “The Craft@Hrs column shows the recommended crew and manhours per unit … Costs in the Labor Cost column are the result of multiplying the manhours per unit by the rate of $46.59 per hour.”
Source: Craftsman Book Company, 2025 National Electrical Estimator, preview pages, 2024
Craftsman’s units run 3.25 hours per 100 ft of 1/2-inch EMT in slab or on a trapeze, 3.50 for 3/4-inch, 4.00 for 1-inch, 4.50 for 1-1/4, 5.50 for 1-1/2, 7.00 for 2-inch, 9.00 for 2-1/2, 10.0 for 3-inch, 11.0 for 3-1/2 and 12.0 for 4-inch; concealed in walls and ceilings adds 0.25 to 0.5 hours per 100 ft on the small sizes. Device covers are 0.05 to 0.10 hours each. The check is mechanical: quantity times unit times a difficulty factor equals hours, and the factor has to be named (occupied hospital, overhead in a live switchgear room, night shift). The only itemised hours in our municipal set are Stilwell Construction’s two Cost Change Estimate Breakdowns for Riverside: 3 hours at $109 for field measurement and ADA drawings, and 64 hours at $109 (16 for engineering coordination, 8 for potholing, 24 for sawcutting and removing asphalt at four foundations, 16 for drypack and patching) plus $29,817 of subcontracts and a 15% markup for a structural redesign. None of those tasks has a unit in a conduit table, which is the general case: the hours that get argued about are the ones the manual does not cover. Federal records never show hours at all.
The rate is the second argument, and it is public. Stilwell billed $109 an hour in Riverside in 2025. The May 2025 median electrician wage was $30.38 an hour nationally, $28.37 in Dallas-Fort Worth and $49.21 in Chicago, so a $109 change-order rate carries a 2.2x to 3.8x load of burden, overhead and profit over the median wage, before the markup line. A contract that states the change-order labor rate by classification, and the burden it includes, removes the second argument.
The third argument is the markup, and five public forms show the range.
Source: Open Factory Public Bid-Tab Price Book, San Antonio, Riverside, El Paso and Kansas City Legistar records
| Record | Labor | Equipment | Materials | Subcontracts | Bond | Method |
|---|---|---|---|---|---|---|
| J3 Company, San Antonio, May 2019 | 55% burden + 25% markup | 15% | 25% | 5% | 2% | Lump sum built from the sub’s quote |
| Stilwell Construction, Riverside, RFC 2, Feb 2025 | $109/hr, 15% on total | 15% | 15% | 15% | none listed | T&M estimate |
| Stilwell Construction, Riverside, RFC 1, Jan 2025 | $109/hr, 10% on total | n/a | n/a | 10% | none listed | T&M estimate |
| Venegas (VEMAC), El Paso, CO 13, Dec 2021 | in unit prices | in unit prices | in unit prices | n/a | n/a | Bid unit prices plus negotiated new items |
| Citadel Electric, Kansas City, CO 5-R1, Nov 2022 | in lump sum | in lump sum | in lump sum | in lump sum | n/a | Lump sum, all impact claims released |
CSV: data/07-markup-schedules.csv
The J3 form is the one to study: 25% on materials, 15% on equipment, 5% on the $126,530.63 subcontract and 2% bond produced $8,983.67 of markup on a $135,514.30 change, and the unused labor line is printed at 80%, a 55% burden plus 25% markup. A markup schedule in the contract, one rate on labor and material and a lower one on subcontracts, settles that line before the first change order; the paid section below writes it out.
What to Do Monday
Set the contingency from the dollars, not the median. On a fixed-price electrical package budget 7 to 8% for change orders and on a mechanical package 11%, which is what the $3.54B of federal work in the Bid-Tab Price Book actually consumed, and hold the last third of it past substantial completion, because 17% of the additive dollars arrive after month 36. Then write four things into the RFQ before the bid opens: a unit-price schedule for the five items that grow (switchgear and panel modifications, feeder conductors by size, fire alarm and low-voltage devices, generator and ATS accessories, conduit and duct bank by size and installation type), a stated change-order labor rate by classification with the burden named, a markup schedule with one rate on labor and material and a lower one on subcontracts, and a T&M cap that converts to lump sum at a threshold. The How to Write an RFQ for Capital Equipment piece carries the template; the Quote Check tool prices the equipment lines against the Bid-Tab bands so the base bid is right before the changes start.
Behind the paywall: the model language for allowances, unit-price schedules, T&M caps and the markup schedule, and the Bid-Tab Price Book’s ranking of the 91 contractors with three or more federal contracts in the set, from eight contractors that closed $55.8M of work with zero priced change orders to the one that closed 51.6% over.