Kind: Reference explainer
By Asif Hussain, Founder and CEO, SpecIndex
A building product is chosen long before anyone buys it. It is chosen when an engineer writes a specification section, and the record of that choice is a public document on most institutional and government projects.
Almost nobody in the manufacturing side of the industry reads those documents at scale. This is a guide to what is in them, what the language means, and where to find them.
Your name appears as the design basis or on a list, and only one of those is a win
There are two, and the difference between them is worth more than most sales meetings.
Basis of design. The specification writer picked a real product, opened its submittal sheet, and wrote the section around it. The dimensions in Part 2 are that product's dimensions. The performance values are that product's values. A control sequence in Part 3 assumes that product's logic. The drawings show equipment with that product's clearance envelope, and the structural engineer sized a curb for it.
Approved equal, sometimes written as acceptable manufacturer. Your name is on a list. Somebody else's product is the one the section was drawn around.
Both look identical to a search for your company name. Only one of them is a win.
We counted that split in the State of the Spec enumeration published on October 14, 2026. Across about 4,800 citable positions, about one in eight was basis of design and the rest were approved equal positions. For each basis of design position there were nearly seven approved equal positions. Approved lists were short. The median list named 2 manufacturers, and about two in five lists named one manufacturer or fewer. The middle position in the table below is not a rhetorical category. In that count it was the larger one by a wide margin.
Basis of design transfers the burden of proof to everyone else
Basis of design is not a legal term of art. It appears in neither AIA A201 nor the Federal Acquisition Regulation. It is a drafting convention, and what it does is transfer the burden of proof. When your product is the basis of design, every competitor who wants in has to demonstrate equivalence against characteristics copied from your data sheet. When you are an approved equal, you are the one demonstrating.
That asymmetry compounds. The drawings agree with you: a rooftop unit four inches taller than the basis of design product does not fit the curb that was detailed, and a luminaire with a different aperture does not match the reflected ceiling plan. The equipment schedule agrees with you, because it carries a manufacturer and model number, and a contractor pricing the job prices what is scheduled. And the engineer has already spent the effort, which matters because specification writers reuse sections. A section written around your product tends to be the starting point for the next project at that firm.
Basis of design does not close the section
Basis of design does not close the section. On public work it is not meant to. A specification that names one product and forbids alternatives is a proprietary specification, and most public owners either prohibit those or require a written justification on file.
So the normal shape of a public section is a basis of design product, a short list of other acceptable manufacturers, and an or equal clause that lets a contractor propose something else under Division 01 procedures. Being basis of design means you start from the inside. It does not mean you finish there.
It also does not make the specification enforceable on your behalf. A specification is a contract document between the owner and the contractor. The manufacturer is not a party to it. If the contractor gets a substitution approved after award, the section still carries your name and you still did not get the order.
Three positions carry three different costs to displace
| Position | What the section says | What it costs a competitor to displace you |
|---|---|---|
| Basis of design | Your product is named, and the requirements are drawn from it | A substitution request, and at times a drawing change |
| Approved equal | Your name appears on a list of acceptable manufacturers | Nothing. The competitor is on the same list. |
| Proprietary or closed | One product named, no substitutions permitted | The section has to be changed by addendum |
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The middle row is where most manufacturers actually live, and it is where the confusion comes from. A brand can appear in hundreds of sections across a territory and be the basis of design in a handful of them. That is not a coverage problem. It is a spec position problem, and it is invisible if the only thing you count is mentions.
Brand names sit in predictable places inside a section
A project manual for a mid sized institutional building runs to several hundred pages. Almost none of it concerns any one manufacturer, and the parts that do are in predictable places.
The structure is CSI's SectionFormat, and it has three parts in the same order every time.
Part 1, General. Administrative. Scope, related sections, reference standards, submittal requirements, quality assurance, warranty, delivery and storage. This part tells you what you will have to produce and prove, not what the product must be.
Part 2, Products. Manufacturers, then the product: performance requirements, materials, fabrication, finishes, accessories, source quality control. This is where a brand name appears and where basis of design is established.
Part 3, Execution. Examination, preparation, installation, field quality control, adjusting, cleaning, protection, demonstration and training. Contractor territory mostly, but a control sequence written here can constrain the product as tightly as anything in Part 2.
If you only read one part, read Part 2. If you read two, read Part 2 and the submittal article in Part 1, because that is where the cost of getting approved lives.
The Facility Services divisions carry the engineered equipment names
Sections are numbered by MasterFormat division. For manufacturers of engineered building equipment, the relevant ones sit in the Facility Services subgroup.
| Division | Title |
|---|---|
| 21 | Fire Suppression |
| 22 | Plumbing |
| 23 | Heating, Ventilating, and Air Conditioning |
| 25 | Integrated Automation |
| 26 | Electrical |
| 27 | Communications |
| 28 | Electronic Safety and Security |
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A six digit section number places a product precisely and the first two digits are the division. Two practical notes: Division 25 can sit empty on a project, with automation content folded into Division 23, and numbering conventions drift between firms and editions, so search by product noun as well as by number.
A brand name turns up in four places, and a name search finds one of them
In the Manufacturers article of Part 2. A list. If it is alphabetical and carries no product detail, nobody on it holds the position. If one entry is called out with a model number, that is the basis of design. Alphabetical order is a reliable tell: a list written alphabetically was not written around anybody.
In the product description of Part 2, without being named. Dimensions, mounting patterns, performance values and accessory names copied from one manufacturer's data sheet. This is where a nominally open section becomes functionally closed.
In the equipment schedule on the drawings. Not in the specification at all. A schedule carrying a manufacturer and model number establishes basis of design whatever the section says, because that is what gets priced.
In Part 3, inside a sequence of operations. A control sequence written around one manufacturer's logic, or a commissioning requirement that assumes a particular interface. Rare, and decisive when present.
The second and fourth are the ones people miss. Searching a project manual for your company name finds the first. It does not find a section written around a competitor's dimensions.
Or equal means meeting the salient characteristics, on evidence you supply
Two words at the end of a product name change the economics of a section, and most of the supply chain reads them wrong.
"Or equal" does not mean any product that does roughly the same job. It means a product that meets the salient characteristics of the named one, as judged by the party named in the contract documents, on evidence supplied by the party proposing it.
On federal work the governing text is FAR 52.211-6, Brand Name or Equal. It requires that a product offered as an equal "meet the salient physical, functional, or performance characteristic specified in this solicitation." The offeror must identify the item by brand name and model number, include "descriptive literature such as illustrations, drawings, or a clear reference to previously furnished descriptive data", and "clearly describe any modifications the offeror plans to make in a product to make it conform to the solicitation requirements."
Two things in the clause matter more than the requirements themselves.
It sets a default: "Unless the offeror clearly indicates in its offer that the product being offered is an equal product, the offeror shall provide the brand name product referenced in the solicitation." Silence is not an equal offer. Silence is an offer of the named product.
And it puts the burden entirely on the proposer. The contracting officer "is not responsible for locating or obtaining any information not identified in the offer." Nobody will look up your data sheet on your behalf.
State and local statutes vary but the structure is nearly always the same. Private work reaches the same place by a different route: AIA A201-2017 Section 3.4.2 provides that "the Contractor may make substitutions only with the consent of the Owner, after evaluation by the Architect and in accordance with a Change Order or Construction Change Directive."
Salient characteristics are the real specification
Salient characteristics are the physical, functional or performance properties that matter for the application. They are the actual requirements. The brand name is shorthand for them.
Where they are listed explicitly, the section is genuinely open and the evaluation is mechanical. Where they are not, the salient characteristics are whatever the reviewer decides they are, and the reviewer can be the engineer who wrote the section around a particular product.
That is the quiet reason an or equal clause is not the open door it appears to be. Telling the two apart is the whole skill.
Genuinely open. "Basis of design: [product]. Equivalent products meeting the performance requirements of this section will be considered", followed by a performance table with tolerances.
Nominally open. "Basis of design: [product]. Or approved equal", followed by a Part 2 specifying a housing depth, a mounting pattern and an accessory that only the named product has.
If you sell against a section of the second kind, the or equal clause is not your route in. Changing the section is.
Who decides changes with the phase, and the cost of a yes rises each time
| Phase | Who evaluates | What it is called |
|---|---|---|
| Before bids are due | The design professional, through an addendum | Prior approval, or substitution during bidding |
| With the bid | The owner or contracting officer | An equal offer under the or equal clause |
| After award | The architect evaluates, the owner consents | A substitution under A201 3.4.2 |
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The cost of a yes rises at every step. Before bids, adding a manufacturer costs an addendum. After award, it costs a change order, and someone has to want it enough to sign one. For a manufacturer this means the or equal clause is most valuable in the narrow window before the bid date and nearly worthless after award, unless the named product has an availability problem.
A substitution request turns on the six promises at the bottom of the form
A substitution request is one page. Most of it is identification. The part that decides the outcome is the block of certifications at the bottom, and on CSI Form 1.5C there are six.
Each one is a commitment somebody has to be willing to make, and most requests fail because one of the six is not true and everyone in the chain knows it.
"Proposed substitution has been fully investigated and determined to be equal or superior in all respects to specified product." In all respects is doing the work. Not equal on the two characteristics you compete on. A reviewer who finds one characteristic where the proposed product is worse can reject on that alone.
"Same warranty will be furnished for proposed substitution as for specified product." Sections can carry an extended warranty requirement in Part 1. If the section requires ten years and your standard is five, this is a commitment to write a special warranty, which somebody at your company has to approve before the form is signed.
"Same maintenance service and source of replacement parts, as applicable, is available." A local presence test disguised as a product test. Institutional facilities staff will maintain this equipment for decades.
"Proposed substitution will have no adverse effect on other trades and will not affect or delay progress schedule." The most commonly untrue of the six. A different unit can mean a different electrical characteristic, structural load or penetration. During the bid period the answer can be genuinely no effect. After award, once material is ordered and coordination drawings are done, it rarely is.
"Proposed substitution does not affect dimensions and functional clearances." Dimensions are the quiet killer. Service clearances, aperture and lens dimensions, mounting patterns. A product that is functionally superior and dimensionally different is not an equal for the purposes of this form.
"Payment will be made for changes to building design, including A/E design, detailing, and construction costs caused by the substitution." The one that ends most conversations. Whoever signs agrees to pay for redesign the substitution causes, which is an open ended exposure. It is why contractors chase a substitution for a large saving and will not bother for a small one.
The six promises predict a narrow set of winners
A substitution succeeds when the proposed product is dimensionally interchangeable, equal or better on every characteristic the section names, has a service presence, and saves enough that somebody will carry the redesign risk. That is a narrow set.
There is also a timing effect with nothing to do with the product. Project manuals set a Division 01 deadline for substitution requests during bidding, commonly ten days before the bid date. A request arriving after it is rejected without evaluation, and in the record that reads exactly like a rejection on merit.
The two phases are different events with different stakes
| During bidding, Form 1.5C | After award, Form 13.1A | |
|---|---|---|
| What is at stake | Which product gets bid | Changing a signed contract |
| Who evaluates | The design professional | The architect evaluates, the owner consents |
| Instrument | Addendum | Change Order or Construction Change Directive |
| Typical outcome | Manufacturer added to the section for everyone | One project changed, for one contractor |
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The right hand column deserves attention from anyone selling. A substitution approved during bidding is published in an addendum, which means every bidder can use it. The manufacturer who did the work of getting approved may have just opened the section for their competitors as well.
One related trap: A201 Section 3.12.8 makes clear that a submittal is not a substitution. Approval of shop drawings does not relieve the contractor of deviations from the contract documents unless the deviation was specifically flagged and specifically approved. Slipping an alternative product through as a submittal does not make it approved.
Public project manuals are public, and finding them is fragmented
The specification for a publicly funded project is a public document. On most jobs anyone can download the full project manual without paying or signing anything.
The difficulty is not secrecy. It is fragmentation. A project might be published by a federal agency, a state procurement office, a transportation department, a university system, a school district, a city, or an airport or housing authority, each on its own site or on one of several dozen commercial portals, and the portals do not talk to each other.
Four steps find the manual that counts
Identify the owner, not the contractor. The entity publishing the documents is the one paying for the work. A school building is published by the district or its construction manager, not by the general contractor.
Match the owner to its tier. Each tier has a default publishing habit, below.
Find the solicitation, not the project. Public owners publish solicitations, which are procurement events with a number and a due date. The project manual is an attachment. Search by solicitation title or number, because the building's name in a press release may not be the name on the bid.
Download the whole set. The technical specifications are one volume among several. You also want the instructions to bidders, which set substitution deadlines, and the addenda, which are published separately and which change manufacturer lists. A project manual read without its addenda can be wrong.
| Owner tier | Where the documents sit | What to watch for |
|---|---|---|
| Federal agencies, including the military construction commands | The federal contract opportunities system at SAM.gov, project manual attached to the notice | Attachments are sometimes behind a controlled access request even when the notice is public |
| State central procurement | A single statewide portal, in administration, general services or management and budget | Some states route construction through a separate facilities agency |
| State transportation departments | A separate letting system on a monthly or biweekly cycle | Heavy civil. Building product sections are thin except on facilities projects |
| Public university systems | The system's procurement office, with campuses publishing separately in some systems | A deep source of Division 23 and 26 work in a state |
| K through 12 districts | The district website, or a regional purchasing cooperative | The most fragmented tier, and the largest by project count |
| Cities and counties | A municipal e procurement platform, of which several dozen are in use | Registration can be required to download |
| Authorities: airport, port, transit, housing | Their own site | High value work that can be missed because it sits outside the state portal |
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Two habits save the most time. When an owner uses a commercial portal, find the portal once and use it for every project that owner runs, because owners rarely switch. And when a portal requires registration, register once with a real company account rather than working around it, because the same account can cover every agency on it.
Public records cover public work, and private work stays private
Everything above applies to public work. Privately bid projects do not publish a project manual. A private developer's office building, a speculative industrial building, most private healthcare and most private multifamily: the specification exists, it names manufacturers, and it is not a public record.
This matters when reading any conclusion drawn from public documents, including this one. If a brand does not appear in a public specification ledger, it is absent from the public documents that were read. It is not absent from the market. Any source presenting a public records count as a complete market picture is overstating what the records support.
The honest framing is that public bid documents are a large, high quality census of institutional and government construction, which is exactly the work where specifications are most rigorous and where a basis of design position is most durable. That is a good thing to be able to measure. It is not everything.
Ten minutes in the right order reaches an answer fastest
For a section you have never seen, in the order that reaches an answer fastest.
- Part 2, Manufacturers. Who is named, and is one of them called out with a model number.
- Part 2, product articles. Anything only one product satisfies: dimensions, mounting, a named accessory, an unusual performance value.
- Part 1, submittals. What you must produce, and whether a prior approval or substitution deadline is referenced.
- Part 1, quality assurance and warranty. Certifications, listings, experience requirements, warranty length. Any of these can exclude you on its own.
- Part 3, sequences. Only if the product is controlled or commissioned.
- The drawings schedule. Confirm what the section said, or discover that it does not matter.
Keep two cross references open. The Division 01 product requirements section, which sets substitution procedure for the whole project, and the instructions to bidders, which set deadlines. A technical section can be silent on both while being governed by both.
One careful read does not scale across a territory
A careful read of one section gives you your position on one project. It does not give you a number you can manage to.
Take a regional manager covering six states. The live projects in that territory, each with a project manual running to several hundred pages, add up past what one reader can hold. The answer they need is a single figure: in what share of the sections that name us are we the basis of design.
None of the usual sources produce that figure. A lead service tracks projects rather than sections, so it can tell you a job exists and not whether you are in it. A distributor sees the bid, which happens after the section was written, so by the time a quote comes in the position is already set. A rep's own relationships cover the firms they know and nothing else. The figure exists only in the specification text, and reading specification text across a territory is the part nobody has time for.
There is a second problem underneath the first. The answer expires. An addendum published a week before the bid date can add two manufacturers to a section or drop one, so a position read in June may not be the position that gets bid in August. A figure worth managing to has to be re-read, not read once.
The practical consequence is that most manufacturers know their spec position anecdotally. They know the jobs their reps worked. They do not know the ones nobody worked, which are exactly the ones where a competitor became the basis of design without anyone noticing.
If you are doing this by hand, the honest approach is to narrow it. Pick the two or three divisions where your products get named at design, pick the states where your public and institutional business actually is, and read those sections properly instead of skimming everything. Then record what you did not read.
That last step is the one people skip, and it is the one that matters most. An absent brand and an unread document look identical in a spreadsheet. Confusing them is how a manufacturer concludes it has no presence in a state when what it really has is no coverage of that state.
Method note
The measured anchor in the first section comes from the State of the Spec enumeration published on this desk on October 14, 2026. That enumeration counted 4,838 citable positions on 1,421 projects, for 15 national brands, in five divisions and ten states. Of those positions, 622 were basis of design and 4,216 were approved equal. Of the basis of design rows, 489 were or equal, 90 were proprietary, 28 were performance based, and 15 were unspecified. The enumeration found 6.8 approved equal positions per basis of design position, a median approved list naming 2 manufacturers, and 41.2 percent of lists naming one manufacturer or fewer. A position was counted when a specification section named a brand in a citable basis of design or approved equal role, with the document and page behind it. The figures are dated as of that October 14, 2026 enumeration. The corpus keeps growing, so the figures are dated and will move.
As a spot check on October 16, 2026, we ran find_brand_positions for Trane with a limit of 1. Its counts block returned 937 total positions on 814 projects, with 120 basis of design and 817 approved equal. That single brand read shows the same pattern as the enumeration, with approved equal positions outnumbering basis of design positions. The rest of this article is reference material grounded in the public sources listed in the front matter, including FAR 52.211-6 and AIA Document A201-2017.