Is a patio included when you buy a restaurant?

It depends on how the property is titled and what the purchase agreement says. For a sale, check the legal description and survey. Shared outdoor areas may not transfer with the building, so confirm the patio is part of what you're buying in writing.

Do restaurants need a permit for outdoor seating?

Often, yes. Requirements vary by city and county and can cover seating counts, hours, music, and placement near sidewalks or parking. Ask the local planning or zoning office about the specific address and your planned use before you rely on the space.

Does a patio always increase revenue?

No. A patio helps most where weather and foot traffic support outdoor dining for much of the year. Model the months it's usable, and don't assume the same sales per seat as the indoor dining room.

A Patio Can Be the Most Valuable Square Foot in a Restaurant: How to Value Outdoor Seating When You Buy or Lease

Two restaurant spaces can have the same square footage and the same rent, and one can do far more business because of a patio. Outdoor seating adds tables without adding walls, and in a warm-weather market it can be the difference between a slow spring and a strong one. The catch for buyers and tenants is that a patio isn't always part of what you think you're getting.

TL;DR

Confirm the patio is in the deal. In a sale, it should be part of the real estate. In a lease, check whether it's inside the leased premises or a shared common area.
Check the rules before you count the seats. Outdoor dining often needs city or county approval, and some places limit hours, music, or seating counts.
Look at access and parking. A patio that's hard to reach, or has no nearby parking, gets used less.
Shade and setting matter. A mature tree or covered area can extend the season more than most upgrades.

Why a patio can change the math

A dining room has a fixed number of seats. A patio adds a second room for part of the year, which changes how much revenue the same rent and labor have to support. Two properties that look alike on paper can perform very differently because one has seating outside and the other doesn't.

That's why patios show up in listings as a feature in their own right, and why serious buyers ask about them early. A patio on a floor plan is not the same as a patio that's usable on a Saturday in April.

Examples: a patio in a sale and a patio in a lease

Two current listings on ListingLedge show how the same feature can appear in different deals:

A freestanding restaurant property for sale, with three outdoor patio areas and a large parking area. In a sale, the question is whether all three patios are part of the real estate, and whether any are shared with neighboring properties.
A restaurant space for lease, with bar seating inside and a patio shaded by a large oak tree. In a lease, the question is whether the patio is inside the leased premises, and who controls it.

Listing descriptions are a starting point, not a guarantee. Before you rely on any feature, confirm it with the agent and in writing.

What to check before you count the patio

Ownership or control. In a sale, check the survey and legal description. In a lease, check the premises description and any common-area rules.
Permits. Ask the local planning or zoning office whether outdoor seating is approved for that address and for your use. Some jurisdictions require a separate permit for an outdoor patio.
Hours and noise rules. A patio that has to close at 9 p.m., or can't have music, is worth less than its seat count suggests.
Accessibility. The path from the parking lot and the dining room should work for wheelchairs and strollers. Ramps and thresholds are common costs.
Upkeep. Surfaces, furniture storage, and drainage are easy to overlook until they fail. Find out who pays for them under the lease or the purchase agreement.

Write the patio into the deal

If the patio matters to your plan, put it in the letter of intent, then in the purchase agreement or lease. Name the area, the permitted uses, and any conditions. For a lease, ask for language on the patio's use, your right to keep it through renewals, and what happens if the landlord changes shared outdoor space. The restaurant letter of intent guide lists the terms to negotiate before due diligence starts.

Common mistakes

Counting seats you can't legally use. Confirm permits before you build a model around a patio.
Assuming the patio transfers with the building. Shared or common outdoor space may not come with the deal the way you expect.
Ignoring the off-season. A patio that's great in spring and fall can cost more to run in summer heat and winter cold. Model the months it's really used.
Paying for a feature you can't use. If the patio is unusable as it stands, the price should reflect that.

The bottom line

A patio can be one of the most useful parts of a restaurant property, but only if it's yours to use, it's permitted for how you plan to operate, and guests can reach it easily. Verify those three things first, then decide how much the outdoor seats are worth to you.