Field Guide 04 · Outdoor kitchens
Why installing a patio will improve your summer BBQ
A level patio and a timber roof over the grill change how a summer cookout works. Here is how to engineer one: footings, hearth clearances, smoke ventilation and cedar roof decking.
Why a patio changes summer cooking
A grill on a lawn works until it rains, or until the sun is high and the cook is standing in it for an hour. A proper patio with a timber roof over the cooking area fixes both. It gives you level, solid ground for a grill and table. It keeps the cook in the shade. And it lets the party carry on through a passing storm.
The trick is building it so smoke, heat and weather are handled on purpose. Here is how we engineer heavy-timber patio pavilions and outdoor kitchens.
Footings and frost depth
Every post in a timber pavilion carries a share of the roof, and in winter, the snow. Each post needs a concrete footing that bears below the frost line. If water under a footing freezes, it expands and lifts the footing, and the frame racks out of square.
| Region | Typical footing depth | Notes |
|---|---|---|
| Lancaster County, PA | 36 in. | Common local requirement |
| Northern PA and New England | 42–48 in. | Deeper in hill country |
| Upper Midwest | 48–60 in. | Some areas deeper |
| Mild coastal and southern climates | 12–18 in. | Footings still need firm, undisturbed soil |
The patio surface itself works differently. Flagstone, bluestone or brick pavers sit on a compacted base, typically 4 in. to 6 in. of crushed stone for foot traffic, topped with a thin layer of stone dust or sand for setting. That base drains water away fast, so the surface moves very little. It is not the same as a footing, and posts should never bear on pavers.
Where the posts come up through the patio, we set them on galvanized standoff bases that hold the end grain at least an inch above the concrete. That gap keeps oak and fir from wicking up water.
Masonry hearths and clearances
An outdoor kitchen under a timber roof brings fire close to wood. The rules here come from two places: the listing and installation manual for your grill or appliance, and the building code for masonry fireplaces. Follow both, and the stricter one wins.
For a wood-burning masonry fireplace, the residential code numbers we design to are:
| Item | Requirement |
|---|---|
| Hearth extension in front, opening under 6 sq ft | 16 in. |
| Hearth extension each side, opening under 6 sq ft | 8 in. |
| Hearth extension in front, opening 6 sq ft or larger | 20 in. |
| Hearth extension each side, opening 6 sq ft or larger | 12 in. |
| Combustibles to front and sides of masonry | 2 in. air space |
| Combustibles to back face of masonry | 4 in. air space |
| Chimney top above roof penetration | 3 ft minimum |
| Chimney top above anything within 10 ft | 2 ft higher |
For gas grills and smokers, the manufacturer sets the clearances. Many call for 24 in. to 36 in. from combustibles on the sides and back. We design the frame so no timber falls inside the listed clearance, and we keep the nearest posts and braces out of the plume entirely.
Smoke hoods and ventilation pitch
Smoke rises, then wind pushes it sideways. An outdoor hood has to win against both. Indoor hoods are tested in still air; outdoor ones fight crosswinds, which is why outdoor-rated hoods often move 1,000 CFM or more. A few rules we follow:
- Oversize the hood. It should overhang the grill by at least 3 in. on each side, more on a windy site.
- Mount it at the manufacturer's height. Too high and smoke escapes around it, too low and grease builds up fast.
- Pitch the roof to help. A steeper roof over the cooking area, 10/12 to 12/12, lets smoke climb to a ridge vent or a small cupola instead of pooling under the eaves.
- Use a metal liner. Above the grill, the roof decking gets a non-combustible liner wherever heat or grease can reach it.
If you are not using a powered hood, a vented cupola over the grill station does a surprising amount of work. Hot air rising out of the top pulls fresh air in under the eaves and carries smoke with it.
Cedar roof decking
Our patio pavilions are roofed with 2×6 tongue-and-groove western red cedar laid over timber purlins. Cedar is light, stable, decay-resistant and smells wonderful on a hot day. We lay it with the V-groove facing down so the underside, the part guests see, looks finished.
Over the decking goes a synthetic underlayment and then standing-seam metal or cedar shingles. Near a grill or fireplace we recommend metal. It sheds snow cleanly, it is a non-combustible roof surface, and embers from a fire pit simply die on it.
Purlin spacing is set by the snow load. Higher loads mean purlins closer together so the decking spans less. In our heavier snow zones we drop purlin spacing from about 4 ft to 3 ft.
A typical grill pavilion, by the numbers
| Item | Specification |
|---|---|
| Frame | Three white oak king-post bents, two 10 ft bays |
| Posts | 8×8 in., 10 ft eave height |
| Tie beams | 8×10 in. |
| Roof | 10/12 pitch, cedar T&G under standing-seam metal |
| Footings | Six piers, 36 in. deep, standoff post bases |
| Patio | Bluestone on 6 in. compacted stone base |
| Cooking zone | Metal-lined ceiling bay, ridge cupola, powered hood |
Before you pour anything
Check with your township about permits. Most roofed structures need one, and outdoor fireplaces nearly always do. Have the gas line run by a licensed fitter. Then decide on the frame. The size of the cooking area, the span you want clear of posts, and your local snow load are all you need to start sizing it.