How Does a Subcontractor Request a Substitution?

A substitution is a request to use a product, material or method other than the one the contract documents name. Whether you may ask, and how, depends on how the specification names the product:

Federal construction contracts state the "or equal" principle plainly: references in the specifications to equipment, material or articles by trade name, make or catalog number "shall be regarded as establishing a standard of quality and shall not be construed as limiting competition", and the contractor may use any equipment, material, article or process that, "in the judgment of the Contracting Officer, is equal to that named in the specifications, unless otherwise specifically provided in this contract" (FAR 52.236-5). The judgment is the owner's, not yours: an equal product is one the reviewer agrees is equal. On many private projects, the substitution procedure sits in a Division 01 section of the specifications, often numbered 01 25 00; read the version on your job, because the deadlines and forms differ from project to project.

The burden is on the requester. The federal "brand name or equal" clause for supplies lists what an "equal" offer must do: identify the item by brand name, make or model, show that it meets the salient physical, functional or performance characteristics, include descriptive literature, and describe any modifications (FAR 52.211-6); unless an offer clearly says the product is an equal, the brand name product must be provided. In its design-build provisions, the submittal guide specification used on federal construction asks for substantiation that a substitute "is equal in function, performance, quality, and salient features" (UFGS 01 33 00, §1.4.2.3.2). A good request to a GC covers the same ground:

• The specified product: section, paragraph, manufacturer and model, and the drawings where it appears.
• The proposed product: manufacturer, model and options, with product data, test reports and certifications.
• A side-by-side comparison of every characteristic the spec states, with the differences marked.
• Why you are asking: unavailable, a lead time that hurts the schedule, a cost saving offered as a credit, or a better product.
• The effect on other work: dimensions, connections, electrical or structural loads, finishes, other trades.
• The effect on cost and time, stated as a number: a credit, no change, or an add; days gained or none.
• The warranty, and whether the manufacturer's representative supports the installation.

An electrical sub on a fictional clinic is told the specified downlight now has a 14-week lead time. It proposes an alternative with a 4-week lead time and a lower price. The comparison:

The request offers a credit of $18 × 140 = $2,520 and names both differences rather than hoping the reviewer misses them: connected load rises by 140 W (140 fixtures × 1 W), and efficacy drops from 100 to 95 lumens per watt (1,500 ÷ 15 and 1,520 ÷ 16). Those are for the electrical engineer to check against the lighting power allowance and the energy code. The federal submittal specification warns that failure to point out variations may cause the Government to require rejection and removal of the work (UFGS 01 33 00, §1.10.1); the same risk applies to any job where a reviewer later finds a difference you did not disclose.

Talk to the GC before you send it. On federal work, variations from contract requirements need the Contracting Officer's approval and are considered where advantageous to the Government, and "Discussion of variations with the Contracting Officer before submission ... will help ensure that functional and quality requirements are met and minimize rejections and resubmittals" (UFGS 01 33 00, §1.10.1). After approval, the substituted product still needs its normal submittal; the approval of a substitution is not the approval of shop drawings.

The question of whether a named product is acceptable can also come up at bid time. Ask it then, in writing, or list the alternative as a voluntary alternate with its price; see how to bid a GC's job as a subcontractor. A design question that is not about a product goes as an RFI instead.

• Sent after the deadline in the specification's substitution section.
• No comparison, only the proposed product's data sheet.
• A difference the reviewer found that the request did not mention.
• No cost effect stated, when the substitute is clearly cheaper.
• Effects on other trades not considered: a larger housing, a different connection, more load.
• Ordered before approval, which turns a request into a demand.

Reviewers have the other side of this in how to review a submittal; for the sub's whole job from bid to closeout, see the subcontractor's guide.

A substitution request is a short, honest case: what the spec names, what you propose, a side-by-side that shows equality and names every difference, and the cost and time effect, sent through the GC before you order.

Send it early, disclose the differences yourself, and install the specified product until the approval is in writing.

Join the Conflo waitlist

1. FAR 52.236-5, Material and Workmanship — Acquisition.gov, U.S. General Services Administration. Read October 22, 2026.
2. FAR 52.211-6, Brand Name or Equal — Acquisition.gov, U.S. General Services Administration. Read October 22, 2026.
3. UFGS 01 33 00 Submittal Procedures (August 2026), §1.4.2.3.2 and §1.10.1 — Whole Building Design Guide, USACE / NAVFAC / AFCEC. Read October 22, 2026.