Kind: Reference explainer, with measured exhibits from the SpecIndex index.
By Asif Hussain, Founder and CEO, SpecIndex
One sentence can end the fight before it starts
On one Alaska air base project, the spec answers the substitution question in a single sentence:
"Trane has been selected as the only manufacturer to supply the requirements for chillers on JBER and no substitutions will be allowed."
(NAF HVAC SITE VISIT, Joint Base Elmendorf Richardson, Alaska; document "Atch 1 - Statement of Work.pdf", pages 3 to 61.)
No form. No process. The answer is no, and it was written before anyone could ask.
Most specs do not say that. We read how the product sections in our index treat the named product, and in about four cases out of five, a challenger is allowed in if it can prove it is as good. The approved list beside the name is short, usually two manufacturers. So on most projects, the real question is not whether you may ask. It is whether your product can prove itself. That proof, and the road it travels, is what this article is about.
A substitution is not a submittal
The two look alike and the contract treats them as opposites. A submittal, a shop drawing, product data, or a sample, proves the contractor will supply what the spec already calls for. A substitution asks to change what the spec calls for. Different ask, different road.
Under AIA Document A201, Section 3.4.2, a substitution needs the owner's written consent, after the architect has evaluated it, and it takes effect through a Change Order or a Construction Change Directive. EJCDC C-700 draws the same line in Paragraphs 7.05 and 7.06, keeping or equal submittals apart from formal substitutes. The point that trips people up is simple: getting a shop drawing approved does not approve an unlisted product hiding inside it. If the substitution procedure was never run, the contract does not recognize the product as approved, however many stamps the drawing carries.
There are two doors, and the early one is far easier
CSI Section 01 25 00, Substitution Procedures, runs the process, and timing decides how hard it is.
Ask before the bid, and your request goes in ahead of a stated deadline so the design team can judge it once, for everyone. If your product is accepted, it is approved by addendum, and every bidder prices the same list. CSI guidance puts that deadline at about 7 to 10 days before bid opening. Treat that figure as guidance about what the standard prescribes; we have not yet counted the deadlines real manuals state, and we say so again in the method note.
Ask after the contract is signed, and the road narrows. Post award requests come in two kinds. A substitution for cause rests on something outside the contractor's control: the specified product was discontinued, its factory lead time now threatens the schedule, or the code changed. A substitution for convenience is about money or effort, and it carries a price: the contractor offers the owner a credit, or a share of the savings. One federal manual states the named product case in a single sentence:
"In order to make a substitution for a 'named' product, submit the details of the requested substitution for Government acceptance."
(Expand/Repair Midfield Facility - AF UMMC, USAF Academy; document "SPECS_W9218F-20-R-0078.pdf", pages 269 to 1042.)
Short road to state. Hard road to travel, because of what you have to carry on it.
The proof is the whole game
The burden sits entirely on whoever proposes the substitute. CSI Form 13.1A is the cover sheet, but the form is not the argument. The evidence behind it is. A complete package answers five plain questions:
- Does it perform the same? A side by side comparison of the properties that matter for this product on this project, tested against the standards the section cites. - Does it comply the same? The code approvals and listing reports the specified product holds, matched. - What does it disturb? Dimensions, weight, and the mechanical, electrical, and structural work around it, shown rather than claimed. - Is it protected the same? A warranty equal to or better than the specified product's. - What does it cost, and what does it save? The credit to the owner stated exactly, with the schedule confirmed to hold.
That list is also the rejection list, read backwards. Requests fail because they arrive late, because the package is a catalog sheet where test data was required, because nobody thought about the work around the product, because a convenience request offered the owner nothing, or because equivalence was claimed on the very qualities the project cares about, finish, color, service life, instead of shown. None of that is a surprise sprung at review. The grounds are published in the procedure itself, before the request is written.
The door is usually open, and the list is short
Here is what we counted. In our October 14, 2026 enumeration of the product sections that name a standard product to design around, about four of five sections let a substitute in against a quality bar, and about one in seven close the door in words, the way the Alaska sentence does. The typical approved list names two manufacturers.
One Division 23 section states the open position and its bar in capital letters:
"FOR THESE BASIS OF DESIGN PRODUCTS, OTHER MANUFACTURERS MAY BE SUBSTITUTED AS LONG AS THE STANDARD OF QUALITY AND CHARACTERISTICS OF THE SUBSTITUTED MANUFACTURER MEET OR EXCEED THE STANDARD OF QUALITY AND CHARACTERISTICS OF THE BASIS OF DESIGN."
(610 CACS Command and Control Facility; document "W912QR11823952_Plans-0000.pdf", pages 78 to 87. Capitalization as in the source.)
Meet or exceed. That is the whole test, printed in the section itself, before any request is filed.
So work in this order
For a manufacturer or a rep, the sequence the evidence points to is short:
- Read the product section before you price anything. [Search projects by state, product and stage](/projects/) is where that language sits in the index. Sort the project into one of three kinds: named and open, named with a short list you can join, or named and closed.
- If the door is open, build the evidence package to the section's own bar. The package is the product. The form is its envelope.
- File inside the window the documents give you. A pre bid approval arrives by addendum and binds the whole bid field. A post award request asks one owner to reopen a settled contract, and a convenience request needs a credit attached.
- If the section is closed in words, say so plainly inside your own team and stop spending there. Put the effort into the specifier relationship and the next project, while its documents are still being written.
For the specifier, the same count cuts the other way. Write the door you mean. If substitutes are welcome against a quality bar, state the bar the way the Division 23 section does, inside the section, where a challenger reads it before deciding to spend. If a product is genuinely the only one, write the prohibition the way the Alaska document does, in one sentence nobody can misread. A short approved list with no stated bar pushes the hardest decision in the process to submittal time, which is the worst time to make it.
The form gets the attention. The language does the deciding. Read the language first, and most substitution questions answer themselves.
Method note and scope
The counts in this article come from the State of the Spec enumeration run on October 14, 2026: a complete count, not a sample, of citable brand positions for 15 national brands across five divisions in the ten states holding the most documents, returning 4,838 positions on 1,421 projects, of which 622 were basis of design positions and 4,216 approved equal positions. Of the 622 basis of design rows, 489 were written or equal (78.6 percent), 90 proprietary (14.5 percent), 28 performance based, and 15 unspecified. The enumeration counted 6.8 approved equal positions for every basis of design position; the median approved list names 2 manufacturers, and 41.2 percent name one manufacturer or fewer. Openness was classified from the language of the section each position was read from. The three quoted exhibits were read live on October 16, 2026; each page citation is the stored span of the section the position was read from, not a single page, and each quote was checked in full before use.
Two limits govern the article. First, the counts describe product section language only. They say nothing about how often substitution requests are made or granted; outcomes are not measured here. Second, the Division 01 procedure layer is unmeasured in this corpus as of October 16, 2026. No count exists yet of the manuals carrying Section 01 25 00, the deadlines those sections state, or the share naming CSI Form 13.1A, because that count runs over the full text of the 354,616 documents the index held with extracted text on that date, and it has not been run. Until it is, the procedure account above rests on the standard documents in the sources, and the 7 to 10 day pre bid window is CSI guidance, labeled as such. We keep the measured and the prescribed apart on purpose.