Teaching Comparability: How We Protect Design Intent

We’ve all seen it: “Manufacturer X or equal.” It feels generous, right? Like we’re keeping the door open for options, collaboration, and creativity. But let’s be honest, “equal” isn’t really possible. No two products are truly identical. They differ in testing methods, warranty terms, composition, performance tolerances, or even the standards they’re certified under. And that’s okay. Those distinctions are what make specifying both an art and a science.

When we write “or equal,” or even “or approved equivalent,” we’re using language that implies a sameness that doesn’t exist. In most of our industry, equivalent and comparable are used almost interchangeably, both suggesting that a substitution should match the performance of the basis-of-design. But in practice, there’s a subtle, important difference.

“Equivalent” tends to read as a claim — a declaration that something is the same.

 “Comparable” reads as an invitation — an opportunity to evaluate how closely something aligns.

That distinction matters, because interpretation invites risk. What’s “equivalent” to the bidder may not be “comparable” to the design intent, and by the time it’s caught, it’s often too late or too costly to correct. Regardless of the term we use, it’s our responsibility to define the basis for comparison. “Comparable” (or “approved equivalent”) only works if we do the work. We have to teach our teams, specifiers, designers, contractors, and owners alike, to perform due diligence: research every listed product, verify claims, and confirm that the proposed substitution truly meets the performance, warranty, and quality standards intended.

Because if we don’t, the decision will almost always default to the least expensive option. That’s the strength of a well-written specification: it doesn’t close the door on alternatives, it simply says, show me how this meets the intent. Specifications are frameworks for alignment. They help us measure what matters, communicate what can change, and protect what shouldn’t. When we move from equal to equivalent, and from equivalent to comparable, we refine our language, and in doing so, we shift from assumption to accountability. That’s where real collaboration begins.