What the term tells you
The architect used one maker's product to draw the details. The dimensions, the structural loads, the power and the clearances all come from that product. The spec names it as the basis of design, or BOD. A drawing note can say the same thing.
Does it mean you must use that product?
Not always. Read the rest of the manufacturers paragraph. Three patterns are common.
- Basis of design with other listed makers. The listed makers are acceptable if their product matches.
- Basis of design with the words or equal. Other makers can be proposed and the architect decides.
- Basis of design with no substitutions. Only the named product is acceptable.
Who pays if another product needs changes
Specs usually put that cost on the contractor. Suppose the design is based on one maker's ceiling-hung backstop. Your product has different attachment points. The added steel or redesign is then your cost, not the owner's. Division 01 often states this rule in the substitution or product requirements section.
What to check before you bid another product
- Compare dimensions and clearances with the drawings.
- Compare weight and attachment points with the structure shown.
- Compare power, controls and other connections.
- Compare performance values, finishes, colors and warranty.
- Check if the spec requires approval before the bid.
Basis of design on the drawings
Sometimes the spec is open and the drawings name a product. A schedule or a keynote can carry a model number that no spec section mentions. Treat that as a conflict and ask about it. Do not assume the drawing note is only an example.
Takeoff Tool flags manufacturer questions, with a link to the spec text or the sheet each one came from.
Bid documents · Updated 11 Nov 2026