PROJECT SUMMARY
Carport project summary
Carport20 × 20 ft · 400 sq ft
- Clearance
- 9 ft
- Roof
- Gable · metal
- Posts
- 4 × 6×6
- Configuration
- Freestanding
- Footings
- 4 · 27 bags
- Difficulty
- Advanced
- Build time
- 3–5.5 days
- Estimated materials
- $1,871–$2,532
Carport Cost & Materials Calculator
Posts, beams, rafters, roofing and footings for a freestanding or attached carport.
Configure
Carport calculator
Roof cover
Attachment
Advanced optionsfine-tune the details…
Estimates are planning aids, not a professional quote. Double-check quantities and product coverage — and any local code or permit requirements — before you buy.
⚠ A carport is a permitted structure almost everywhere, and the roof must be designed for your local wind and snow loads — underbuilt carport roofs collapse under snow. Confirm post size, footing depth and rafter spacing with your building department.
Cost breakdown
Material only · national-average rates
| Lumber & Decking | $1,089–$1,473 |
| Roofing | $333–$451 |
| Connectors & Brackets | $182–$246 |
| Concrete & Footings | $161–$217 |
| Finishing & Sealant | $68–$92 |
| Fasteners & Hardware | $39–$53 |
| Total | $1,871–$2,532 |
Excludes tools, delivery, tax and permit fees. Labor not included — this is a DIY materials estimate.
Shopping list
Every item · grouped by store sectionThese are affiliate links: we may earn a commission if you buy through them, at no extra cost to you. It never changes what the calculator recommends — the shopping list comes from your dimensions, not from what pays.
Lumber & Decking
- 4× 14 ftPosts — 6×6 pressure-treated — 2 per side · ~9 ft clearance
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- 8× 16 ftBeam plies — 2×10 PT — 2 × 2-ply beams
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- 22× 16 ftRafters — 2×8 (11.3 ft) — gable · 3:12 · 24" OC
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- 2× 16 ftRidge board — 2×10
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- 2× 8 ftKnee-brace stock — 6×6 / 4×4 — 8 braces for lateral stability
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Roofing
- 16× 12 ft panelsMetal roof panels — 3 ft wide panels + closures & screws
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Concrete & Footings
- 27× bagsConcrete — 80 lb bags (footings) — 4 footings · 14" dia × 42" deep
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Connectors & Brackets
- 4× eaPost bases (standoff)
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- 4× eaPost-to-beam brackets
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- 44× eaHurricane / rafter ties
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Fasteners & Hardware
- 1× boxStructural connector screws
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Finishing & Sealant
- 2× galExterior stain / sealer — protect posts and exposed framing
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Tools
✓ required · ○ helpful
- Post-hole digger or power auger — 4 footings
- Circular saw
- Cordless drill / impact driver
- 4 ft level + post level
- String line & batter boards — squaring the posts
- Socket / ratchet set — lag screws & brackets
- Extension ladders or scaffold — beam & roof height
- Impact wrench
- Metal snips / nibbler — trimming panels
Project notes
- Estimates are a planning aid, not engineered drawings. A carport needs a permit nearly everywhere and the roof must be sized for your local snow and wind loads — get the beam, rafter and footing sizes confirmed before you build.
- Footings are figured at 14" diameter and 42" deep (below a 36" frost line). Set the post bases square and at one height, and let the concrete cure before loading the beams.
- Set and plumb all posts first and trim them to a common height, then lift the doubled beams on with post-to-beam brackets. Add knee braces at every post — a carport has no walls, so the bracing is what keeps it from racking.
- Tie every rafter to the beam with a hurricane tie, and on a metal roof, lap the panels into the prevailing wind and seal the fastener gaskets. Flash an attached ledger so water sheds outward.
About this calculator
How to estimate a carport
Enter a size and clearance height and the whole structure gets laid out: the 6×6 posts and their footings, the doubled beams, the rafters and ridge, a metal or shingle roof, and every bracket, tie and brace — with the tools, a cost range and a build time. It handles both a freestanding carport and one attached to the house.
Choose a gable or single-slope roof, metal or shingles, and the framing and roofing adjust together. Open advanced options for roof pitch, frost depth and waste. A carport is a permitted, load-bearing structure, so treat this as a budgeting takeoff and confirm the framing against local snow and wind loads.
Step by step
How to build a carport
A step-by-step walkthrough to go with your plan above. Follow the product instructions and any local code or permit requirements as you work.
- 1
Lay out and check square
Mark the post centers with batter boards and string, and equalize the diagonals so the layout is square. Confirm your permit and local snow/wind requirements before you dig.
- 2
Dig and pour the footings
Auger each footing below the frost line, set a standoff post base or anchor, and pour the concrete. Get the bases square and at a consistent height, and let it cure.
- 3
Set and plumb the posts
Stand each 6×6, brace it plumb on two faces, and pull a string to align the tops. Leave them long, then trim them all to one height with a level or laser.
- 4
Raise the beams
Assemble the doubled beams on the ground, lift them onto the posts with a helper, and lock them down with post-to-beam brackets. For an attached carport, flash and lag the ledger to the house first.
- 5
Set the rafters
Cut one rafter as a pattern, test-fit it, then cut and hang the rest at 24 inches on-center, tying each one to the beam (and ridge, for a gable) with a hurricane tie.
- 6
Brace the structure
Add knee braces at every post. A carport has no walls, so the bracing is what stops it from racking in wind — don't skip it.
- 7
Install the roof
Screw down metal panels lapped into the prevailing wind with gasketed screws, or sheathe, dry-in and shingle for an asphalt roof. Add closures or drip edge at the eaves.
- 8
Seal and inspect
Seal the posts and exposed framing, double-check every bracket and tie, and call for your inspection where required before parking under it.
Equip the job
Recommended gear for this build
Hand-picked categories that match the shopping list above. Links open a current selection so you can compare brands and prices.
These are affiliate links: we may earn a commission if you buy through them, at no extra cost to you. It never changes what the calculator recommends — the shopping list comes from your dimensions, not from what pays.
Connectors & BracketsHeavy 6×6 post base bracketsStandoff bases keep post ends off the footing so they don't wick water and rot.
$18–28 ea
Connectors & BracketsHurricane / rafter tiesTie every rafter to the beam against uplift — code requires them and inspectors check.
$1–2 ea
RoofingMetal roofing panels & closuresLightweight, fast, and ideal for the low pitch of a carport roof.
$22–32/panel
Fasteners & HardwareStructural wood screwsDrive straight into beams and braces — no pre-drilling or lag wrenches.
$30–50/box
ToolsPost levelStraps to each post and shows plumb on two faces hands-free while you brace.
$8–15
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Answers
Frequently asked questions
What size carport do I need?
For a single car, plan at least 12 feet wide and 20 feet long; for two cars, 20–24 feet wide. Add length if you want to walk around the vehicle or store gear, and raise the clearance to 12+ feet for trucks, vans or an RV. The calculator scales the posts, beams and roof to whatever footprint and height you set.
Do I need a permit for a carport?
Almost always, yes. A carport is a permanent, load-bearing structure, so building departments require a permit and a roof designed for your local snow and wind loads, with footings below the frost line. Treat this planner as a budgeting and shopping takeoff, and confirm the post, beam, rafter and footing sizing with your local code or an engineer before building.
Metal roof or shingles?
Metal panels go up fast, shed snow well, weigh less on the structure, and suit the low pitches carports usually have — they're the most common choice. Shingles look more like a house roof and can match an attached home, but they need a solid sheathed deck and a steeper minimum pitch. The calculator swaps the roofing materials to match your pick.
Freestanding or attached?
An attached carport hangs one side from a ledger bolted to the house, so it uses fewer posts but must be flashed and lagged into solid framing. A freestanding carport stands on its own posts on all sides, which needs more footings and good knee bracing for stability but doesn't touch the house. The planner adjusts the post count and adds ledger hardware for the attached option.