What Is a Substitution Request?
By Wyatt Cooper · Published · 3 min read
Key takeaways
- A substitution request proposes a product, material or system other than the one specified, with the evidence that it does the same job.
- The design team accepts or rejects it in writing; until then the specified product is the one to buy.
- Some owners separate an "or equal" (an equivalent product, proposed early) from a substitution (a different product that may change adjacent work).
A substitution request is a contractor's formal proposal to use a product, material or system other than the one the specifications name. The contractor shows the alternative meets the specified function, performance and quality, and the architect or engineer accepts or rejects it in writing. Until it is accepted, the specified product stands.
How a substitution request works
In its design-build provisions, the federal guide specification for submittals asks the contractor to submit a requested substitution with "substantiation" that the substitute "is equal in function, performance, quality, and salient features" to the product named in the accepted proposal (UFGS 01 33 00, 1.4.2.3.2). Where the contract prohibits substitutions of named products, the same paragraph treats the request as a "variation" instead.
The City of Los Angeles draws a line many specs draw: an "or equal" proposes a product "equal or better to the one specified" that normally needs no change to adjacent work, while a substitution proposes one that "can serve the same function" but is not the equivalent and "typically require[s] modifications to adjacent work". Its Master Specifications want or-equal proposals within 30 calendar days after notice to proceed; later ones are processed as substitutions (LA Bureau of Engineering, 16.4). Your own specification's product-requirements section sets the deadline and the form.
Example
Substitution request 03: Type L2 downlight
- Specified
- Manufacturer A downlight, 14-week lead time
- Proposed
- Manufacturer B downlight, 5-week lead time
- Salient features compared
- Lumens, color temperature, dimming, trim size and ceiling cutout: all match
- Effect on other work
- None; same 6-in. cutout
- Price
- Credit of $1,840 (40 fixtures × $46)
- Decision
- Accepted by the electrical engineer in writing
The arithmetic: 40 × $46 = $1,840. The nine weeks saved (14 − 5) is often the real reason to ask; a long-lead item that threatens the schedule is a common trigger.
Substitution, or-equal, RFI or submittal?
| Request | What it asks |
|---|---|
| Or-equal | Accept an equivalent product to the named one |
| Substitution request | Accept a different product that serves the same function |
| RFI | Explain what the documents require |
| Submittal | Review the specified (or accepted) product before it is ordered |
An RFI asks what the documents mean; a substitution request asks to change what they require. Once a substitute is accepted, its product data still goes through the normal submittal review, as how to prepare a submittal describes.
The bottom line
A substitution request is the contractor's case that a different product will do the same job, decided in writing by the design team.
Send it early, compare the salient features side by side, and order nothing until it is accepted.
Sources
- UFGS 01 33 00, Submittal Procedures (August 2026) — Whole Building Design Guide (USACE / NAVFAC / AFCEC). Read October 22, 2026.
- 16.4 Substitution and "Or Equal" Proposals — City of Los Angeles, Bureau of Engineering, Project Delivery Manual. Read October 22, 2026.
Questions
Who approves a substitution request?
The architect or engineer responsible for that part of the design, often with the owner's agreement. The contractor sends it through the general contractor.
Can a substitution be rejected for looks alone?
It depends on the contract. The Los Angeles manual says aesthetics generally are not a reason to reject a functionally equivalent product, except for architectural finishes.
Does an accepted substitution change the price?
It can. A cheaper substitute is often offered with a credit, and any change to the contract sum is made by change order.
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