Classic 4-post pergola plan

Beta — engineering review in progress

Four 6x6 posts, doubled beams and open rafters with knee braces: the classic free-standing pergola over a patio.

Size: 12' x 12'
Posts: 4 6x6 on footings
Est. materials: $695–$2,816
Skill level: Medium

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Classic 4-post pergola in a backyard (representative image) — Representative image.

Sizes, framing and cost

Classic 4-post pergola by size
Size	Posts	Beams	Rafters	Footings	Materials (est.)
8' x 8'	4	2-2x8, 4' 8 1/2" span	2x8 at 24 in	12 in round, 36 in deep	$695–$1,418
10' x 10'	4	2-2x10, 6' 6" span	2x8 at 24 in	12 in round, 36 in deep	$761–$1,660
12' x 10'	4	2-2x12, 8' span	2x8 at 24 in	16 in round, 36 in deep	$905–$1,972
12' x 12'	4	3-2x10, 8' span	2x10 at 24 in	16 in round, 36 in deep	$1,015–$2,326
14' x 12'	4	3-2x12, 10' span	2x10 at 24 in	16 in round, 36 in deep	$1,142–$2,816

Worked out by our plan engine. Costs are estimates from typical US home-center prices.

What the materials cost

Pressure-treated (Economy) and cedar above the posts (Durable), from the plan's own shopping list (12' x 12').

Economy materials

$1,015 to $1,486

Pressure-treated wood throughout. Same posts, sizes, footings and connectors.

Lumber: $467–$634
Concrete and footings: $280–$392
Structural connectors: $174–$300
Fasteners and hardware: $94–$160

Durable materials

$1,536 to $2,326

Cedar beams, rafters and braces. Same posts, sizes, footings and connectors.

Lumber: $988–$1,474
Concrete and footings: $280–$392
Structural connectors: $174–$300
Fasteners and hardware: $94–$160

Estimates from typical US home-center prices; your local prices will vary. Prices last updated: Oct 23, 2026. Not included: sales tax, delivery, tools, gravel/base material, paint or stain.

Plan specifications & limitations

Rafter span
2x10 at 24 in: at most 10' 7" (deck joist table, conservative for an open pergola)
In this plan: 10' · Source: web-media.awc.org
Rafter overhang
At most 2' 6"
In this plan: 1' · Source: web-media.awc.org
Beam span
3-2x10: at most 9' 1" (deck beam table, conservative)
In this plan: 8' between posts · Source: web-media.awc.org
Posts
6x6 pressure-treated on uplift-rated post bases; 6x6 posts allow 14 ft (IRC Table R507.4)
In this plan: 8' to the beams · Source: codes.iccsafe.org
Knee braces
Post bases alone do not stop a free-standing frame from rocking; braces at every post both ways
In this plan: 4x4, 24 in legs, 1/2 in lag at each end · Source: Our design choice
Uplift
Every rafter tied to each beam; posts in uplift-rated post bases
In this plan: Hurricane ties and post bases · Source: buildsite.com
Footings
At least 12 in below grade; frost protection not required for small free-standing accessory structures (local codes may still ask)
In this plan: 16 in round, 36 in deep (deeper for uplift) · Source: codes.iccsafe.org
Height
Eave at most 10' for that exception
In this plan: 8' under the beams · Source: codes.iccsafe.org

Sizing rules used by this plan, with sources
Rule	What every plan uses	In this plan	Source
Rafter span	2x10 at 24 in: at most 10' 7" (deck joist table, conservative for an open pergola)	10'	web-media.awc.org
Rafter overhang	At most 2' 6"	1'	web-media.awc.org
Beam span	3-2x10: at most 9' 1" (deck beam table, conservative)	8' between posts	web-media.awc.org
Posts	6x6 pressure-treated on uplift-rated post bases; 6x6 posts allow 14 ft (IRC Table R507.4)	8' to the beams	codes.iccsafe.org
Knee braces	Post bases alone do not stop a free-standing frame from rocking; braces at every post both ways	4x4, 24 in legs, 1/2 in lag at each end	Our design choice
Uplift	Every rafter tied to each beam; posts in uplift-rated post bases	Hurricane ties and post bases	buildsite.com
Footings	At least 12 in below grade; frost protection not required for small free-standing accessory structures (local codes may still ask)	16 in round, 36 in deep (deeper for uplift)	codes.iccsafe.org
Height	Eave at most 10' for that exception	8' under the beams	codes.iccsafe.org

Loads
An open frame with no roof, sized with the deck tables (40 psf live + 10 psf dead), which is more than an open pergola carries. Check local snow, wind and frost depth with your building department. Frost depth varies by location: check your local code before you dig.
No roof, no extra loads
Do not add a solid roof, a swing, a hammock or hanging planters heavier than a few pounds: the plan is not sized for them.
Wind and uplift
Uplift-rated post bases, a hurricane tie on every rafter and knee braces at every post. In high-wind areas, ask your building department.
Footings
Round concrete footings on undisturbed soil, 36 in deep; local frost depth may ask more. Never bolt the posts to an existing patio slab.
Permits and HOA
Many cities and counties require a permit for structures above 120 sq ft. Some require one for smaller ones. Many places need a permit for a deck or a pergola; HOA rules may limit size, height or color. Checking permits, setbacks and HOA rules is your responsibility.
Not an engineered plan
The plan is a general guide built from published prescriptive tables. It is not stamped or engineered, and it is not a substitute for engineering or local approval.

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Questions about this plan

What size is the classic 4-post pergola?

8' x 8', 10' x 10', 12' x 10', 12' x 12', 14' x 12', 8 ft under the beams (7 or 7-1/2 ft also possible) and about 9' 6 1/2" to the top.

How much does it cost to build?

Estimated materials run $695 to $2,816, depending on size and the material group (pressure-treated or cedar above the posts), concrete and connectors included.

How deep are the footings?

16 in round, 36 in deep in this plan, on undisturbed soil. Frost depth varies by location: check your local code before you dig.

More in our guide: Pergola post, beam and rafter sizes

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