Engineering letter

An engineering letter is a brief document, sealed and signed by a licensed engineer, certifying a specific and narrow fact: that an existing structure can carry a proposed load, that an installation as built meets a standard, that a detail is adequate as constructed.

Where it applies in the lifecycle

• Preparation. Provided up front where the department is known to require one.
• Plan review. Very often requested in response to a comment, as the accepted way to close out a question the drawings did not answer.
• Inspections. Requested by an inspector when a field condition differs from the approved drawings and someone qualified needs to certify it is acceptable.

Typical uses

• Certifying an existing roof can carry new equipment
• Confirming an existing wall can take a new opening
• Certifying an installation completed before it could be inspected
• Resolving a field condition that departs from the plans

Practical points

The letter must be sealed by an engineer licensed in the project's state, and it should state precisely what is being certified and on what basis, including whether the engineer inspected the condition personally. A vague letter draws a follow-up comment and costs another cycle.

Where an inspector requests one because work was covered before inspection, the letter is the alternative to opening the work back up. That makes it worth having the engineer look before the drywall goes on, not after.