Deck and Pergola Permits: What Inspectors Look For in Structural Details

Where a deck attaches to the house is the single highest-risk connection in the entire structure — it's the detail most associated with deck collapse when done incorrectly. Permit drawings need to specify the ledger fastener type, spacing, and flashing method, not just show a line where the deck meets the house.

Footing depth requirements are driven by the local frost line, which varies significantly by region, so a footing detail that's correct in one state can fail inspection in another. Post sizing and beam spans need to be calculated for the actual joist span and tributary load — not assumed from a similar-looking deck down the street.

Guardrails are required once a deck surface exceeds a certain height above grade (commonly 30 inches, though this varies by jurisdiction), and the code is specific about baluster spacing — generally no gap large enough to pass a 4-inch sphere — along with graspable handrail profiles on stairs with a minimum number of risers.

Pergolas are often assumed to be exempt from structural review because they're not fully enclosed, but most jurisdictions still require permit drawings for post footings, beam sizing, and — increasingly — wind uplift connections, especially in regions with higher wind speed requirements.

Framing inspectors consistently flag the same three items: undersized or improperly fastened ledger connections, footings that don't reach the required frost depth, and guardrail spacing that doesn't meet the baluster gap requirement. All three are catchable on paper before construction starts, which is exactly why they belong on the permit drawings in dimensioned detail rather than as a general note.