Deck & Porch Builders in St. Louis: Options, Costs & Top Contractors

You want more outdoor living space, but you're not sure whether a deck, a porch, or some combination makes the most sense for your St. Louis home. That's a bigger decision than it sounds — especially when Missouri winters punish the wrong material choice and a poorly set footing can heave out of the ground by March.

Here's what you need to know about building a deck or porch in St. Louis: the real costs, the permit situation, how to find a contractor who can handle both, and which structure actually makes sense for your property.

For a broader look at deck pricing across different materials and regions, see our complete deck cost guide. Timing your build right can also save thousands — check our guide on the best time to build a deck.

Deck vs Porch vs Screened Porch: What's the Difference?

These terms get used interchangeably, but they're structurally different — and that affects your budget, your permit requirements, and how much use you'll get out of the space in St. Louis's climate.

Deck: An open, elevated platform attached to your house (or freestanding). No roof, no walls. You're fully exposed to weather. In neighborhoods like Soulard, Tower Grove South, and Webster Groves, decks are the most common backyard addition.

Porch: A covered structure, usually with a roof tied into the home's existing roofline. Open sides, but the roof gives you rain protection and shade. Front porches are a defining feature of many St. Louis neighborhoods — think Compton Heights, Shaw, and the older homes in Kirkwood.

Screened porch: A covered porch with screened walls on all sides. Keeps out mosquitoes (and St. Louis has plenty from June through September). Gives you a bug-free, shaded space without full enclosure.

Quick Comparison

The right choice depends on how you'll actually use the space. If you mostly grill and entertain on summer evenings, a deck works fine. If you want to sit outside during a July thunderstorm without getting soaked — or eat dinner without swatting mosquitoes — a screened porch is worth the premium.

Deck & Porch Costs in St. Louis (2026 Pricing)

St. Louis sits in a moderate cost-of-living zone, but the shorter building season (roughly May through October) means contractor schedules fill up fast. Book by March if you want your project done before summer.

Deck Costs by Material

These are fully installed prices including framing, footings, railing, and stairs. Your actual cost depends on height off the ground, railing style, and site access. A second-story deck on a hillside lot in Sunset Hills will cost significantly more than a ground-level platform in Brentwood.

For a deeper look at how composite decking compares across brands, check out the best composite decking options in Canada — the brand comparisons apply regardless of where you're building.

Porch and Screened Porch Costs

Adding a roof changes everything. Expect these ranges:

• Open covered porch: $50–$90/sq ft installed. The roof structure, tie-in to your existing roofline, and proper flashing add substantial cost.
• Screened porch: $70–$120/sq ft installed. Includes the roof, screened wall panels, a screen door, and often a finished ceiling.
• Three-season room: $100–$175/sq ft installed. Adds insulated windows, better flooring, and sometimes electrical work.

A 200 sq ft screened porch in St. Louis typically runs $14,000–$24,000 all in. A three-season room the same size can hit $20,000–$35,000.

Screened Porch vs Open Deck: Which Handles St. Louis Winters Better?

St. Louis weather is brutal on outdoor structures. You get hot, humid summers, then temperatures that swing between freezing and thawing all winter long. That freeze-thaw cycle is the single biggest threat to your investment.

What Freeze-Thaw Does to Decks and Porches

Water gets into wood grain, concrete footings, and gaps between boards. It freezes, expands, thaws, and repeats — sometimes multiple times per week in a St. Louis January. Over a few seasons, this cycle:

• Cracks concrete footings that weren't poured below the frost line
• Splits wood decking boards — especially pressure-treated pine that wasn't properly sealed
• Pops fasteners as boards expand and contract
• Causes frost heave, literally pushing footings and posts upward

How Each Structure Holds Up

Open decks take the full force of Missouri weather. Snow sits on the surface, meltwater pools in low spots, and ice forms between boards. If you go with an open deck, composite or PVC decking is the smart play — it won't absorb moisture the way wood does. Pressure-treated lumber can work, but you're committing to annual sealing to keep moisture out, and you'll need to clear snow promptly.

Screened porches have a major advantage: the roof keeps snow and direct rain off the deck surface. You'll still get wind-driven moisture, but the structure lasts dramatically longer because it's not sitting under snowpack for weeks at a time.

For footings in either case, St. Louis's frost line sits at roughly 36 inches deep. Any reputable builder will dig to at least that depth — often going to 42 inches for safety. If a contractor quotes you shallow footings, walk away. Frost heave on a porch can crack the roof connection to your house, and that's a five-figure repair.

If you're weighing material durability, affordable deck builders in Chicago face similar freeze-thaw challenges — their material recommendations apply here too.

Material Recommendations for St. Louis

• Best overall: Composite or PVC decking on pressure-treated or steel framing. Zero moisture absorption, no annual maintenance, handles temperature swings without splitting.
• Budget option: Pressure-treated pine with aggressive annual maintenance. Seal every spring, replace damaged boards as needed. Expect a 10–15 year lifespan vs 25+ years for composite.
• Premium choice: Ipe hardwood is incredibly dense and naturally weather-resistant, but it's expensive and difficult to work with. Most St. Louis contractors have limited experience with it.

Use PaperPlan to visualize different decking materials on your own home before committing — it helps you see how composite vs wood actually looks against your siding and trim.

Three-Season Room Options in St. Louis

A three-season room splits the difference between a screened porch and a full addition. You get windows instead of screens (usually removable or sliding), insulated walls, and a finished interior — but typically no HVAC.

Why Three-Season Rooms Work Well in St. Louis

St. Louis has about 8 months of usable outdoor weather if you have some protection from the extremes. A three-season room extends your season from roughly April through November. On a mild December day (and St. Louis gets plenty of 45–55°F days in early winter), you can still use it comfortably.

What to Expect

• Cost: $100–$175/sq ft installed, or $20,000–$35,000 for a 200 sq ft room
• Construction time: 3–6 weeks depending on complexity
• Permit required: Yes — this is treated as a building addition in most St. Louis municipalities
• Foundation: Typically requires a concrete slab or piers to frost depth (36"+)

Three-Season Room vs Four-Season Addition

If you need the space in January and February, a four-season addition is the move — but you're looking at double the cost or more. For most St. Louis homeowners, a three-season room hits the sweet spot.

Finding a Builder Who Does Both Decks and Porches

Not every deck builder can handle porch construction, and not every porch contractor wants to build a simple deck. The skill sets overlap but aren't identical.

What to Look For

Roofing integration experience. A porch roof has to tie into your existing roof without creating leaks or ice dams. In St. Louis, ice dams are a real concern — if the porch roof doesn't have proper ventilation and flashing, melting snow backs up under the shingles and into your walls. Ask specifically about their approach to roof tie-ins.

Footing expertise. Any builder working in St. Louis needs to understand frost line requirements. They should be digging to 36 inches minimum without you having to ask.

Licensing and insurance. Missouri doesn't require a state contractor license, but St. Louis County and many municipalities do. Verify your contractor is licensed for the jurisdiction where you're building — the City of St. Louis and St. Louis County are separate entities with different requirements.

Red Flags

• No mention of footing depth. If a contractor doesn't bring up frost line requirements unprompted, they may not have experience with Missouri's climate.
• Quoting a porch without a structural engineer. Any roof structure attached to your home should have engineering behind it.
• Can't provide references for porch projects. A deck portfolio doesn't prove porch competence. Ask for porch-specific references.
• Pushing to start in November. The realistic building season for outdoor structures in St. Louis is May through October. Starting late risks incomplete weatherproofing before winter.

How to Vet Contractors

1. Get at least three bids — but compare scope, not just price
2. Check the Missouri Attorney General's contractor complaint database
3. Verify insurance — ask for a Certificate of Insurance naming you as additional insured
4. Visit a current or recent job site if possible
5. Confirm they'll pull the permit (not ask you to do it)

For more on evaluating deck contractors in similar Midwest markets, see how homeowners approach finding deck builders in Indianapolis and Columbus.

Permits for Porches vs Decks in St. Louis

Permit requirements differ between the City of St. Louis and St. Louis County municipalities. Here's the general framework:

When You Need a Permit

In St. Louis, deck permits are typically required for structures:

• Over 200 sq ft in area
• Over 30 inches above grade at any point
• Attached to the house (some jurisdictions)

Porches and screened porches almost always require a permit because they involve a roof structure and attachment to the existing building.

Three-season rooms require a building permit in every jurisdiction — they're classified as additions.

Permit Costs and Timeline

• Deck permit: Typically $75–$200 in St. Louis area municipalities
• Porch/screened porch permit: $150–$400, sometimes more if engineering review is required
• Three-season room: $300–$800+ depending on scope
• Timeline: Allow 2–4 weeks for permit approval. Plan submissions in spring can take longer due to volume.

Contact the St. Louis Building/Development Services department for the City, or your specific municipality's building department for County locations. Unincorporated St. Louis County falls under the County's Department of Public Works.

Inspections

Expect at minimum:

• Footing inspection before concrete is poured
• Framing inspection before decking or roofing goes on
• Final inspection after completion

Your contractor should coordinate all inspections. If they suggest skipping the permit process, that's a major red flag — unpermitted work can kill a home sale and void your insurance.

For a broader look at how deck permits work across different cities, deck permit requirements in Philadelphia covers a similar regulatory structure.

Frequently Asked Questions

How much does it cost to build a screened porch in St. Louis?

A screened porch in St. Louis typically costs $70–$120 per square foot installed. For a standard 12x16 (192 sq ft) screened porch, expect to pay $13,500–$23,000 including the roof structure, screening, door, and a composite or pressure-treated floor. Costs increase if you need electrical work, ceiling fans, or upgraded flooring.

Do I need a permit to build a deck in St. Louis?

Most likely, yes. St. Louis requires permits for decks over 200 sq ft or over 30 inches above grade. Even smaller decks may need a permit if they're attached to the house, depending on your specific municipality. Porches and screened porches always require a permit. Contact your local building department before starting — permit fees are minor compared to the cost of tearing out unpermitted work.

What's the best decking material for St. Louis weather?

Composite or PVC decking handles St. Louis's freeze-thaw cycles best. These materials don't absorb moisture, so they won't crack, split, or rot from repeated freezing and thawing. Pressure-treated wood is the budget option but requires annual sealing to perform well. Cedar looks great but needs even more maintenance in Missouri's humid climate. For more on choosing composite decking brands, the performance comparisons are useful regardless of location.

When should I book a deck or porch builder in St. Louis?

Book by March for a summer build. St. Louis's building season runs roughly May through October, and experienced contractors fill their schedules early. If you wait until May to start getting bids, you may not get on the calendar until August or September — which leaves little margin before weather shuts things down.

Can one contractor build both my deck and screened porch?

Yes, but verify they have experience with both. Deck building and porch construction require different skill sets — particularly roof framing, flashing, and structural connections. Ask for porch-specific references and photos, not just deck projects. Hiring one contractor for a combined deck-and-porch project often saves 10–15% compared to splitting the work between two builders, since they can share mobilization costs and coordinate the design.