Class code 5645 covers carpentry in residential construction — one of the most-used construction classes in the system, and one of the most fought-over at audit because of what it borders: cheaper interior trim work on one side, expensive roofing on the other.

Who falls under 5645

Carpentry operations on detached one- or two-family dwellings: framing, exterior trim, siding in many states, deck construction, and general residential carpentry work.

Common misclassification traps

Boundary disputes define this code. Crews that touch roofs risk payroll moving to 5551; commercial carpentry belongs in different codes; and ‘general contractor’ operations doing carpentry with subs need clean records separating self-performed carpentry payroll from subcontracted trades — plus certificates from every sub, or their payroll lands here too.

Rate context

5645 typically runs mid-to-high single digits up to the teens per $100 of payroll by state — a serious rate that still beats roofing by a wide margin, which is exactly why the 5645/5551 boundary gets audited. See our guide to how premiums are calculated for the full mechanics.

Related codes

5651 (interior carpentry/cabinet work) where applicable, 5551 (roofing), 5437 (interior trim in some states), 5403 (commercial carpentry in some states).

Class code 5645 FAQs

What does class code 5645 cover?

Carpentry work on detached one- and two-family residential dwellings — framing, decks, exterior trim, and general residential carpentry.

What’s the biggest misclassification risk with 5645?

The roofing boundary: crews that touch roofs risk having payroll moved to 5551 at multiples of the rate. Documented scopes of work and payroll records are what hold the line at audit.

What does 5645 cost per $100 of payroll?

Mid-to-high single digits to the teens per $100 of payroll depending on state — expensive, but far below roofing, which is why the classification boundary matters so much.

Can one business use multiple class codes?

Usually, yes — most businesses have an office/clerical component (8810) alongside their governing class, and payroll can often be split when records support it. Done correctly, splitting payroll across codes is one of the most reliable premium reductions available. Done sloppily, it’s an audit dispute.

Not sure your operation is classified correctly? Misclassification runs both directions — some businesses overpay for years, others build audit bombs. Have us review your class codes, or browse the full class code guide.