What's Required in St. Louis
- Building permit for any deck or porch except a wooden platform resting on the ground or a rock base, 12 in or less above grade, with no roof and no permanent foundation
- Fee: $25 application plus $19 to $30 for work up to $3,000, then $10 per $1,000 of estimated cost or fraction thereof
- Plans: site plan with distances to each property line, foundation or pier plan, framing plan, elevations and a typical deck section
- Footings and piers 30 in minimum below finished grade (R403.1.4.1 as amended) unless built to R403.3, ASCE 32-01 or on solid rock
- Drawings must show post and beam sizes, the bolted beam-to-column connection, joist size and span, and how the deck attaches to the house
- All framing, decking and railing of approved naturally durable or pressure-treated wood
- Handrails and guardrails drawn on the plans; the handout calls for a guard once the floor is 15 1/2 in above grade
- No deck or stairs across two parcels; keep the side yard (4 ft each side in the A district) or get a notarized maintenance agreement from the neighbor
- Photographs with the application in a historic district or within 300 ft of a park, historic district or landmark
Do You Need a Permit to Build a Deck in St. Louis?
Yes. The Building Division lists porches, decks and retaining walls as permit work, and the city's 2018 Residential Code ordinance (70795) requires a permit to construct, enlarge or alter a structure. The one exemption that matters for backyards is item 25 of Section 105.2: a concrete patio slab or a wooden patio or deck that rests directly on the ground or a rock base, with no roof or canopy, no permanent foundation, and no more than 12 inches above adjacent grade. Anything on posts and footings, anything attached to the house with a ledger, and any deck with a roof needs a building permit. Minor like-for-like repairs to an existing deck, such as replacing handrails, treads or balusters without touching the structural members, are exempt under item 11; replacing joists, beams, posts or footings is not.
St. Louis Deck Permit Rules by Scenario
| What you are doing | City filing | Rule |
|---|---|---|
| Attached deck on posts and footings, 24 in above grade, $8,000 | Building permit, $105 ($25 + $80) | Permit criteria page; fee table |
| Ground-level wood platform resting on the ground or a rock base, 12 in or less above grade, no roof, no footings | None | Ord. 70795 Sec. 105.2 item 25 |
| Replacing decking boards, handrails or balusters like-for-like without touching joists, beams or posts | None | Sec. 105.2 item 11 |
| Replacing joists, beams, posts or footings, or enlarging the deck | Building permit | R105.1; criteria page lists structural beams and joist replacement |
| Adding a roof or canopy over a deck | Building permit | Item 25 exemption excludes covered decks |
| Cutting a new door opening onto the deck | Building permit; header or lintel size on the drawings | Deck handout 3.9 |
| Deck at a house in a City Historic District or within 300 ft of a park | Permit plus photographs; Cultural Resources review | Deck handout; permit criteria page |
How Much Does a Deck Permit Cost in St. Louis?
The building permit fee follows the estimated cost of the deck, including labor. The Building Division's table charges a $25 application fee plus $19 (total $44) for work up to $1,000, $23 ($48) up to $2,000, $30 ($55) up to $3,000, then $10 per $1,000 or fraction above that. An $8,000 deck pays $25 + $80 = $105, a $15,000 deck $175, and a $25,000 composite deck $275. The $25 application fee is paid at filing and the permit fee when the permit is ready to issue; nothing is refundable, and cards carry a 2.55 percent fee online. Start building first and Table R109.4 adds a surcharge of $90 on a permit fee of $51 to $200 or $240 on $201 to $500.
What Do Deck Plans Need to Show?
The Plan Exam sun-deck handout asks for six sheets: a site plan with distances to each property line, a foundation or pier plan, a framing plan, elevations, a typical deck section, and any extra details. The reviewer wants footing size and depth, post and beam sizes with the bolted beam-to-column connection, joist size, spacing and span, how the deck attaches to the house, stair risers and treads, and handrails and guardrails. All framing, decking and railing must be naturally durable or pressure-treated wood. The amended frost rule (R403.1.4.1) puts footings 30 inches below finished grade. The handout's 2001 note calls for a guard once the deck floor is 15 1/2 inches above grade; the plan examiner applies the current code, so draw the guard and ask if your deck is low.
How Do You Apply for a Deck Permit in St. Louis?
Apply online at stlcitypermits.com (homeowners can register) or at the Permit Section in Room 425, City Hall, with five sets of plans. An owner-occupant of a one- or two-family home may draw the plans without an architect's seal. The Plan Exam page says decks, porches and room additions may be approved over the counter at the Hot Spot desk (9 AM to 3 PM), and the portal says 70 percent of permits issue the same day; routed reviews typically take 2 to 4 weeks. The permit is issued in the owner of record's name for six months and can be extended in writing. Request each inspection at least one working day ahead and do not conceal structural framing before it is approved.
Zoning: a deck may not be built across two parcels, and the handout's rule of thumb is 4 feet from each side line with 10 feet total, which matches the A district side yard. A tight side setback can sometimes be solved with a notarized maintenance agreement from the neighbor.
How to Get a Deck Permit in St. Louis
Confirm the deck needs a permit
On posts, attached to the house, roofed or more than 12 in above grade: building permit. A platform resting on the ground under 12 in with no roof: none.
Draw the six sheets
Site plan, foundation or pier plan with 30 in footings, framing plan, elevations, deck section and details. An owner-occupant can draw them; no seal needed.
Apply and pay the $25 application fee
Upload at stlcitypermits.com or bring five sets to Room 425. The Hot Spot desk (9 AM to 3 PM) can approve decks over the counter.
Pay the permit fee and post the permit
Once approved, pay the balance ($105 for an $8,000 deck), print the permit and display it on site. Pull a separate electrical permit for any new circuit.
Call inspections as you go
Give at least one working day's notice. Footings and framing must be approved before they are covered, and a final inspection closes the permit.