"Or Equal" Substitutions

When the reroof spec names another sub-purlin brand

Many metal reroof specifications name one retrofit sub-framing product as the basis of design, often Roof Hugger™ under Section 13 34 21, and then allow an "equal" product with prior approval. The name in the spec sets the standard a product has to meet, not the price you have to pay. Here is how that approval works, what to submit, and how TopHat helps you get the TopHat Zee Strip or TopHat Subframe approved before bid.

Send Us the Spec Section

1. Read the specification

  • Basis of design with "or equal" / "or approved equal": other products can be used if the architect or engineer approves them, usually before bid.
  • "No substitutions": the named product is required. On private work, the owner can still choose to allow an alternate; ask early.
  • Division 01 (Section 01 25 00, Substitution Procedures, or similar): sets the deadline, the request form, and who submits. Pre-bid requests are commonly due 7 to 10 days before bid opening.
  • Federal projects: "brand name or equal" purchases list the salient characteristics the equal product must meet. Your submittal should address each one.

2. Assemble the substitution request

Approvers are checking that the substitute does the same job with no added risk. A complete package answers that in one read:

  1. The project's substitution request form, filled in.
  2. Product data and the CSI specification section.
  3. A side-by-side comparison with the basis-of-design product: profile, gauge, how it fits the existing panel ribs, attachment, and fastener spacing.
  4. Project-specific structural calculations sealed by a professional engineer licensed in the project's state, for the project's wind and snow loads and existing purlins.
  5. Test reports behind the design values (see TopHat test results).
  6. Standard details (PDF and DWG) for the existing roof profile.
  7. Any conditions you will accept, such as on-site fastener pull-out tests.

3. Approval comes by addendum

If the architect or engineer accepts the request, the approval is issued to all bidders in an addendum, and any conditions come with it. Keep the addendum with your bid. After award, substitutions are usually harder to get, so start before bid whenever you can.

Example: a public reroof bid

On a 2024 State of Iowa roof replacement bid (Iowa Department of Administrative Services, RFB935700-01), Addendum No. 2 listed under Section 13 34 21, Structural Retrofit Roof Sub-framing: "Top Hat Zee-Strip is approved."

The same addendum added on-site fastener pull-out testing, with results for the field, perimeter and corner zones. Plan for conditions like this; they are a normal part of approving an equal.

How TopHat helps

Send us the sub-framing spec section, the roof plan or roof size, the existing panel profile, and the bid date. We will put together the product data, specification, test reports, details and project-specific engineering for your substitution request. Two weeks is our normal turnaround once we have all the project information. When a spec calls for on-site fastener pull-out testing, TopHat can help arrange it through its approved fastener supplier. TopHat is made in the USA, ships to jobsites nationwide with delivered pricing, and keeps popular sections in inventory. Pricing an equal is often how owners find out what the named brand was costing them.

Start a substitution request

Roof Hugger is a registered trademark of its owner. TopHat Framing Systems is not affiliated with Roof Hugger, LLC. This page is general guidance; always follow the project's contract documents.