Basis of design versus proprietary spec: keeping a project competitive and enforceable

Every wallcovering specification sits somewhere on a scale from open to closed. An open performance spec names only measurable properties and lets any conforming product win. A closed proprietary spec names one product and forbids substitution. Most real projects need a point in between, and choosing that point deliberately is a large part of the specifier's craft.

The basis-of-design method is the usual middle ground. The section names a specific product, the one the designer selected and detailed the job around, labels it "basis of design," then lists the performance criteria that define an acceptable alternate: the ASTM F793 category, the CFFA type and weight in ounces per linear yard, the ASTM E84 class, the width, and the repeat tolerance. A competing manufacturer may propose an equal, but it is judged against those numbers, which keeps the bid competitive while protecting the design intent.

A fully proprietary spec is legitimate in narrow cases. A tenant matching existing corridors across a portfolio, or an owner standardizing maintenance stock, has a real reason to write a single product with "no substitutions." On publicly funded work, procurement statutes commonly disfavor sole-source finishes and may require a documented justification, and those rules vary by state and agency, so the language is used with cause rather than by habit.

The substitution procedure is the safety valve, and it belongs in Part 1. It should state when substitution requests are due — many project manuals set a cutoff around ten days before bid, though the number is the owner's to set — what the submitting contractor must provide to prove equivalence, and that the burden of proof sits with the party proposing the change. A specifier who writes that procedure clearly rarely has to fight a value-engineering proposal later, because the standard for an acceptable swap was fixed in writing before anyone sharpened a pencil.