The boards are only one part of the deck
The North American Deck and Railing Association’s Deck Evaluation Guide inspects stairs, footings and posts, beams and joists, the ledger, the deck boards, and the handrails and guards as separate items. Replacing one part does not tell you the condition of the others. Ask the person assessing the deck which parts can stay and why. If the connection to the house is hidden, the assessment should say so rather than assume it is fine.
When reusing the frame is more plausible
Trex’s guide to deck demolition says that if the ledger flashing still works, the framing is properly spaced and structurally sound, and all fasteners meet current building code, you might be able to remove only the boards and install new decking on the existing frame. It also says to inspect the joists for rot, splitting and spacing, and to reinforce or replace damaged framing first. It notes that many modern decking materials need different framing, such as joists 12 or 16 inches apart rather than 2 feet. So ask for the exact proposed product and its installation instructions, and whether the existing framing suits it.
What should pause a boards-only plan
Visible decay, cracked or damaged framing, corroded connections, or a ledger attachment that cannot be evaluated are reasons to deal with the structure before choosing new boards. NADRA’s Deck Evaluation Checklist records these conditions, flags several that need additional analysis, and states that an evaluation using it does not by itself make a deck code compliant.
If the deck moves, sags, or has a loose guard or step, keep people off that area and arrange an on-site assessment. Do not jump on it, take connections apart, or crawl under it to test it. Photos taken from a safe spot can help explain the concern, as described in what photos help with a home repair estimate, but they do not replace an inspection.
Make the estimate explain what is unknown
Ask for a written scope that lists board replacement separately from any framing, connection, stair or guard work. Ask who will review conditions found once the old boards are off, when work would pause for your decision, and how a change would be documented. Confirm the permit question with the local building office using the actual work: in Philadelphia, start with L&I’s permits and certificates page; in Bucks County, the township or borough. Our checklist for hiring someone for a home repair covers the rest, and more deck questions are on our decks page.