Guides / Substitution requests

How to write a substitution request that gets approved

A substitution request asks the engineer to accept a product that is not named in the spec. It succeeds when the reviewer can see, line by line, that the product meets the same requirements.

Before you submit

• Check the spec's substitution procedure: deadlines, forms and whether substitutions are allowed at all.
• Compare the substitute with the basis-of-design product against every requirement in the section, not only the headline ratings.
• List every difference, including dimensions, weight, electrical data and service clearances that affect other trades.

What to include

• A side-by-side comparison with a page reference for every claim.
• Product data with the submitted model and options highlighted.
• Listings, certificates and manufacturer letters the section requires.
• A clear statement of any deviations and why they are acceptable.
• Any effect on schedule, cost or coordination with other trades.