How to build a patio cover

Plan the cover before you buy lumber

A patio cover looks simple: a few posts, a beam, rafters and a roof. The decisions that make it last, and pass inspection, come before the first cut.

Attached or freestanding. An attached cover hangs one side on a ledger board bolted to the house, so it needs fewer posts, but the city reviews it like an addition. A freestanding cover stands on its own posts and is reviewed as an accessory structure^[3]. In Plano, a detached cover must have at least two open sides and be structurally independent^[3].

Size and height. Under the IRC patio cover appendix, a patio cover is one story and no taller than 12 feet^[1]. The roof must carry at least 10 pounds per square foot of live load, or your local snow load where that is higher, plus the code's minimum wind loads^[1].

The roof. Open slats give shade. A solid roof keeps rain off. Weight matters: the Laguna Hills standard drawings only cover roofing assemblies weighing less than 10 pounds per square foot, such as asphalt or fiberglass shingles and cap sheets; heavy roofs such as concrete, clay or slate tile need calculations and plans by a licensed engineer^[4]. Colton's standard handout applies only to flat roofs with a slope under 2 in 12, without tile or a deck on top^[6].

The distance to your property lines. Milpitas does not let a patio cover come closer than 3 feet to a side or rear property line^[2], and Laguna Hills requires a one-hour firewall when the face of a post or wall is less than 5 feet from the property line^[4]. Check yours before you settle the size.

How open it stays. If you plan screens or panels later, remember the rule: the longer wall and one more wall must stay at least 65 percent open or glazed below 6 feet 8 inches^[1].

Materials and tools

The exact grades come from your city's handout or your approved plans. As one real standard, East Palo Alto, California, asks for^[5]:

• framing members of Douglas Fir-Larch number 2 or better;
• standoff post bases under every support post;
• new, unused structural materials;
• hot-dipped zinc-coated galvanized or stainless steel fasteners in preservative-treated wood.

Laguna Hills adds that rafters must be marked Douglas Fir grade number 2 or better, beams number 1 or better, framing hardware ICC approved for the use, and the roof covering Class A or better^[4]. Tools: a post-hole digger or auger, a level and string line, a circular saw, an impact driver, a drill with long bits for the ledger bolts, ladders and a helper.

Step by step

Mark the layout and call for utility locates

Snap the outline of the cover on the patio or ground, mark each post and check the distances to the property lines against your site plan. Before digging, have buried utilities located. If you will cut an existing slab for posts, Milpitas warns to check first whether it is a post-tensioned slab: cutting a tendon can be very dangerous and expensive to repair^[2].

Fasten the ledger to the house framing

The ledger carries half the roof, so it must bite into real structure. In Milpitas, lag screws must fully engage a wood stud or rim joist and have washers^[2]. Do not hang the cover on decorative facing: Plano forbids anchoring a patio cover to brick or siding veneer^[3]. And do not lean on the roof overhang: in Laguna Hills, no patio cover may rely on the existing rafter tails or roof projection without an engineer's calculations^[4].

Dig the footings and call the first inspection

Dig the post footings to the size and depth on your approved plans. The first inspection comes now: in Laguna Hills, after the footing excavation and before any concrete is poured, together with a check of the solid wood backing for the ledger bolts^[4]. Colton likewise requires footing excavations, forms, reinforcement and column bases to be inspected before any concrete is placed^[6].

Posts can sit on a slab without separate footings only where the frost depth is zero, the slab is at least 3.5 inches thick and each column carries 750 pounds or less^[1].

Set the posts on raised bases

Pour the concrete, then set the post bases. Colton requires posts to rest on concrete piers or metal post anchors that stand at least 8 inches above exposed ground and at least 1 inch above a surrounding concrete slab^[6]. Plumb each post and brace it temporarily.

Install the beam and the lateral bracing

Set the beam (header) on the posts with approved post caps or straps. The beam size depends on the span between posts: use the span table of your city's handout or your plans. A cover also has to resist sideways movement, and Milpitas asks the plans to show how: embedded posts, knee braces or another approved method^[2].

Hang the rafters and block them

Fix the rafters to the ledger with hangers and to the beam with ties or clips. Milpitas requires rafters to be supported laterally at the ends and at each support by solid blocking, unless their ends are face-nailed to a header or rim joist^[2]. Give the roof a slope so water drains: Colton's standard detail shows at least 1/4 inch per foot^[6].

Sheathe, roof and call the framing inspection

Lay the sheathing or the open slats, then call the framing inspection before the roofing hides the work. In Laguna Hills, the second inspection covers all framing, the roof sheathing and the nailing^[4]. Then install the roof covering and flash the joint with the house wall.

Add electrical work with its own permit

Fans, lights and outlets are electrical work. Plano asks for an electrical plan when they are part of the cover^[3], and Laguna Hills requires a separate electrical permit when the project adds any electrical work^[4].

Pass the final inspection

The final inspection comes once the roof covering is installed^[4]. Keep the signed permit card with your house papers: it is your proof that the cover was approved.

Mistakes that fail inspections

• Pouring concrete before the footing inspection. The inspector needs to see the holes and the forms first^[4][6].
• Lagging into veneer or siding only. The ledger must reach a stud or rim joist^[2][3].
• Resting on the roof overhang without an engineer's calculations^[4].
• Posts sitting directly on soil or a slab instead of raised bases^[5][6].
• Turning the cover into a room. A patio cover cannot be used as a carport, garage, storage room or habitable room^[1], and East Palo Alto requires covers used for storage or living space to be removed at the owner's expense^[5].

Do you need a permit to build a patio cover?

Everything above happens under a permit in most cities. Santa Clarita, California, lists patio covers among the projects that require a building permit, and it can issue a stop work order for unpermitted construction, with fines and a lien on the property if work continues^[7]. The permit page explains when you need one and what the city asks for: drawings, a site plan and the inspections listed here.

How we can help

Our All-in offer gives you the paperwork side of this guide, done for your address: your city's patio cover rules with links, a scaled site plan, the framing drawings for the permit application, the forms and the fee, then our team's review and follow-up until the permit is approved. You build.

Common questions