Planning a deck.

A deck looks simple on paper: posts, beams, joists, boards, a railing. That simplicity is why so many deck projects get stuck. The parts that matter to a permit office are the ones you can't see in a finished deck: how it's attached to the house, what it stands on, how high it sits and how close it comes to the property line. Get those right on paper and the rest of the job is carpentry.

This guide walks through what to decide, what to measure and what to ask before you buy a single board. It is general guidance. Rules vary a lot from town to town, and your local permit office makes the final call.

Why decks get extra attention

Most building departments treat decks as structures, not furniture. A deck carries people, sometimes a lot of them, at a height where a failure hurts someone. The two details inspectors care about most are the connection to the house (often called the ledger) and the footings that carry the posts. A deck that pulls away from the house or settles unevenly is the failure they are trying to prevent.

Zoning is the other half. Even a deck that is structurally perfect can be turned down if it sits too close to a lot line or pushes the property over a limit on how much of the lot can be covered. That's why many towns send deck applications through both a building review and a zoning review.

When a permit usually comes up

Every town draws its own lines, but these are the questions that usually decide whether a deck needs a permit:

• Is it attached to the house? Attached decks are commonly treated more strictly than freestanding ones, because the ledger connection matters so much.
• How high is the walking surface? Many towns set a height above grade where a permit, guards, or both become required.
• How big is it? Some towns exempt small platforms below a size threshold. Others don't exempt anything.
• Does it serve a door? A deck that serves an exterior door can bring in rules about landings and stairs.
• Is there a roof, hot tub or screen enclosure planned? Extra load and extra structure usually means extra review.

You'll notice there are no numbers in that list. That's on purpose. The exact thresholds come from your town's adopted code and its local amendments, and they really do differ. Sully looks them up from your town's own pages first and labels where each rule came from.

What to decide before you call anyone

You'll get better answers, from the office and from Sully, if you've made a few decisions first:

1. Attached or freestanding. If attached, know what the house wall is made of where the deck meets it. Siding over sheathing over a rim joist is a very different conversation from brick veneer.
2. Footprint. A rough length and width, and whether it wraps a corner.
3. Height. Where the deck surface lands relative to the door threshold and the ground below. On a sloped yard, measure at the low corner too.
4. Stairs. Where they come down and what they land on.
5. Materials. Pressure-treated lumber, composite decking, or something else. It affects joist spacing and fasteners.
6. Who builds it. Doing it yourself, hiring it out, or a mix. Some towns let homeowners pull their own permit for work on their own home; others require a registered contractor for certain work.

What to measure

A tape measure and twenty minutes in the yard will save a lot of back-and-forth:

• Distance from the house to each side property line and to the rear line, if you can locate it. A survey or plot plan from your closing papers helps.
• The deck's planned distance from each of those lines.
• Height from the ground to the planned deck surface at the house and at the far corners.
• Door threshold height, so the deck surface lands at the right step down.
• The location of anything underground or overhead: gas and electric service, septic, well, overhead wires.

Before you dig footings, call your state's one-call utility locating line (811 in the U.S.). It's free and it's the single best habit in this whole guide.

Questions to ask your permit office

When you call or visit, these questions get you most of what you need in one conversation:

• Does this deck need a building permit, a zoning permit, or both?
• Which code edition and local amendments apply to decks here?
• Do you have a deck handout or typical deck detail I can follow?
• What setbacks apply to a deck in my zoning district?
• What do you want with the application: a site plan, a framing plan, footing details, product sheets?
• Which inspections are required, and at what stage do I call for each one?
• Can I, as the homeowner, pull this permit myself?

Write down the answers and the name of the person you spoke with. If something later contradicts what you were told, that note matters.

What offices commonly ask for

Applications vary, but deck packets often include:

• A site plan showing the house, the deck and distances to property lines.
• A framing plan with joist size, spacing and direction, beam size and post locations.
• Footing details: size, depth and what the posts connect to.
• Ledger attachment details, if attached.
• Guard and stair details where they apply.
• Product information for composite decking or engineered connectors.

Sully's filing packet pulls these into one PDF: a cover sheet, your project details, a conceptual schematic from your sketch, the rules that apply with their sources, and a checklist of what your office says it wants.

Common reasons deck applications get sent back

• The site plan doesn't show distances to property lines.
• The ledger attachment isn't described, or the house wall can't take one.
• Footing depth or size isn't shown.
• The framing plan doesn't match the size on the application.
• Guards or stairs are missing from the drawings even though the deck is high enough to need them.

Most of these are paperwork gaps, not design problems. A complete packet fixes them before they happen.

Do it yourself or hire a pro?

Plenty of homeowners build solid decks. The deciding questions are honest ones: Have you set footings and hung joists before? Is the deck high off the ground? Does it attach to an older house where you're not sure what's behind the siding? Is there a hot tub in the plan? The higher, heavier and more attached the deck, the more a licensed contractor or engineer earns their fee. Sully's report includes a plain "should you hire a pro?" note for your project, and some towns require a design professional for certain decks.

How Sully helps with a deck

Tell Sully the project and your city and state. Sully asks one question at a time, the ones that actually change the answer, and turns a photo of your sketch into a clean conceptual schematic. Then Sully reads your town's own pages first, then the county, then the state, then the model code, and labels every rule with where it came from. You get a permit report with a verdict, the rules grouped by source, who to call, the form if the town posts one, ordered steps and common rejection reasons. The materials list is sized only from details you've confirmed, with a waste allowance and any missing measurement called out. If Sully can't find your town's deck rule, the report says so and tells you who to ask.

Related reading: Do I need a permit for a deck? and What the permit office wants in an application.