What's included
- Solid-roof covers tied into the house and framed for Boise's 25 psf minimum roof snow load, with flashing at the tie-in and a gutter and downspout plan so runoff doesn't land on the deck stairs.
- Open pergolas in cedar, pressure-treated wood or aluminum, with rafter and slat spacing chosen for the shade you want at 4 p.m. in July rather than at noon.
- Footings sized for the concentrated post loads a roof creates, set below the 24-inch frost line and usually larger than the deck's own footings.
- Wind uplift and racking resistance: hold-downs at the posts and knee braces or rigid connections, especially on open-sided structures in higher-wind areas such as Star, which designs for 115 mph.
- Engineering where it applies: Boise usually treats gazebo and pergola structures as pole construction that needs structural engineering by an Idaho-licensed engineer.
- Ceiling finishes, fans and lighting planned with the framing. In Boise, low-voltage outdoor lighting needs no electrical permit, while 110-volt fixtures and fans do.
- Snow-shedding layout: roof slope and edges placed so snow sliding off the cover, or off the taller house roof above it, lands away from stairs, doors and walkways.
Materials we use
| Category | Options |
|---|---|
| Solid roof covers | Shingle or metal roof matched to the house · Insulated aluminum roof panels · Polycarbonate panels for a light-transmitting cover · Tongue-and-groove or soffit ceiling finishes |
| Pergolas | Western red cedar · Pressure-treated pine, stained · Powder-coated aluminum · Louvered aluminum systems with adjustable blades |
| Structure | Glulam or built-up beams · 6x6 posts on standoff bases · Engineered footings below 24 inches · Rafter ties, hold-downs and knee braces |
| Drainage and flashing | Step and counter flashing where the cover meets the house wall · Aluminum gutters and downspouts sized for the cover's roof area · Downspout extensions or drains routed away from footings · Self-adhered membrane at low-slope tie-ins |
How the work goes
Shade and load study
We watch where afternoon sun hits the deck, where snow slides or drifts off the house roof, and how a cover would meet the existing roofline or wall. Headroom under the beam, the slope needed to drain, and the height of the eaves set the options.
Structural design
Posts, beams, rafters and footings are sized for snow, wind and dead load. Covers outside prescriptive limits go to an Idaho-licensed engineer; for attached covers, Boise's Residential Patio Cover Construction Policy can remove the need for engineering when a design meets it.
Permits and HOA
Boise requires a permit for any attached patio cover regardless of size, and for stand-alone pergolas over 200 square feet. Meridian's threshold for detached shade structures is also 200 square feet. HOAs often review roof color and material to match the house.
Build the structure
Footings go in first, then posts, beams and the ledger or house tie-in. On an existing deck, cover posts get their own footings rather than bearing on deck joists, passing through the decking where the layout calls for it.
Roof, finish and drainage
Roof panels or pergola slats, flashing, gutters and downspouts, ceiling finishes and lighting go on last. We run a hose over the finished roof before leaving so water ends up where the plan says it will.
Treasure Valley conditions we design for
- Permit needed above
- 12 in
- Frost depth
- 24 in
- Ground snow load
- 20 psf
- Design wind
- 90 mph
- Nights ≤ 32°F / yr
- 108
- Annual precip
- 11.51 in
Sources: City of Boise — Residential Construction brochure; City of Boise — current codes & design criteria; NOAA NCEI U.S. Climate Normals 1991–2020, Boise Air Terminal (USW00024131)
Red flags to watch for in any quote
- Cover posts bearing on deck joists or on the deck's existing small footings. Roof loads need their own path to the ground, and a deck footing sized for foot traffic isn't sized for snow on a roof.
- A cover tied into the house with no detail for flashing where it meets the existing roof or wall.
- No answer when you ask what roof snow load the design uses. A cover detailed for a snowless climate isn't built for Boise.
- A pergola quote with nothing about uplift or bracing. Open structures still catch wind, and shade panels or louvers catch more.
- "Pergolas never need a permit." In Boise, any attached patio cover does, and stand-alone structures over 200 square feet do.
- A solid cover whose drip edge lands right over the stairs or the door you walk out of. Every melt-off ends up as ice on the busiest step of the deck.
Budgeting? Our covers & pergolas cost guide breaks down published Treasure Valley price ranges.
Frequently asked questions
- Do I need a permit for a pergola or patio cover in Boise?
- For an attached patio cover, yes, regardless of size. For a stand-alone pergola or gazebo, Boise requires a permit once it exceeds 200 square feet, and the city usually treats those as pole construction that needs an Idaho-licensed engineer's design. Setbacks come from Planning at 208-608-7100, and height limits can apply in some areas. The Boise deck permit guide covers the deck side of the submittal.
- Do I need a permit for a freestanding pergola in Meridian?
- Meridian lets a detached shade structure — pergola, arbor, gazebo or patio cover — go without a building permit if it is under 200 square feet. Over that, it needs a Residential Patio Cover permit and has to meet rear and side setbacks. A cover attached to the house is a different case and needs a permit. HOA rules apply either way. The Meridian deck permit guide explains the deck rules that sit alongside it.
- How much snow does a covered deck have to hold in Boise?
- Boise's design criteria set a 20 psf ground snow load and a 25 psf minimum roof snow load, and Star publishes the same snow figures. Snow sliding or drifting off a taller house roof can add more where the cover meets the house, which is why the beam nearest the wall often ends up the heaviest member. Our deck snow load resource explains how those numbers become beam and footing sizes.
- How much does a covered deck cost?
- A cover adds roof framing, larger footings, flashing, drainage and sometimes engineering, so it is priced separately from the deck surface. The covered deck cost guide collects published ranges with sources. In our calculator, covers and pergolas are listed as items priced at the site visit rather than guessed from square footage, because the engineering and footing count vary so much from one house to the next.
- Can you add a cover to my existing deck?
- Often. The deck frame usually wasn't designed for roof loads, so the cover gets its own posts and footings, set outside the deck or through it to new footings below. We also check the house wall or roof where the cover ties in. If the deck itself is near the end of its life, rebuilding both at once can cost less than doing them separately.
- Pergola or solid roof — which works better for Boise summers?
- A solid roof gives full shade and keeps rain and snow off, but it darkens the rooms behind it and carries snow load. A pergola gives partial, moving shade, lets low winter sun through and needs lighter framing. Louvered aluminum systems sit between the two at a higher price, opening for sun in spring and closing against July afternoons. Our covered deck ideas show common layouts.
- Does wind matter for a pergola in the Treasure Valley?
- Yes. Boise designs for 90 mph wind and Star for 115 mph, and an open-sided structure with shade cloth, louvers or a solid roof is pushed upward as well as sideways. Posts need hold-downs into their footings and bracing against racking. Privacy panels or roll-down shades added later raise the wind load, so mention them at design time.
- Does a covered deck need gutters?
- Usually. A solid roof collects every bit of rain and snowmelt that lands on it and drops it along one edge, often right where people step off the deck. A gutter and downspout carried away from the deck footings and the house keeps that water off the stairs and out of the soil around the footings, where it would feed frost heave. Open-slat pergolas don't need them; louvered systems usually drain through channels in their beams.
Sources
- City of Boise — 301 Current Codes and design criteria (2018 IRC; snow, wind, frost depth)
- City of Boise — Residential construction permit guide (deck, patio cover, pergola rules)
- City of Star — Adopted codes and design criteria
- City of Meridian — Residential detached accessory structures handout
- NOAA NCEI U.S. Climate Normals 1991–2020, Boise Air Terminal (USW00024131) — monthly
- American Wood Council — DCA 6 Prescriptive Residential Wood Deck Construction Guide
Last reviewed .