Deck & Porch Builders in London: Options, Costs & Top Contractors

You want more outdoor living space, but should you build a deck, a porch, or both? And does the contractor you hire actually matter when it comes to which one you pick? In London, Ontario — where winters dump snow for months and freeze-thaw cycles punish poorly built structures — the answers to those questions matter more than you'd think.

Here's what London homeowners need to know about costs, building options, and finding a contractor who can handle the full scope of outdoor construction in this climate.

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 three terms get thrown around interchangeably, but they're distinct structures with different costs, permits, and uses.

Deck: An open, elevated platform — usually built off the back of your home. No roof, no walls. It's the simplest and most affordable option. Most London backyards have room for one, and it's the fastest to build.

Porch: A covered structure, typically at the front or back of the house, with a roof that ties into your home's roofline. Porches can be open-air or enclosed. Because of the roofing component, they cost more and require more complex framing.

Screened Porch: A porch with mesh screen walls on all sides. You get airflow and views without the mosquitoes. In London, screened porches are popular because they extend your usable season — you're protected from bugs in June and falling leaves in October.

Quick Comparison

A key consideration for London: any structure with a roof needs to be engineered for snow loads. The city sees significant accumulation, and a porch roof that isn't properly designed can become a serious liability. This isn't a detail to overlook — it affects framing lumber sizes, post spacing, and footer depth.

Deck & Porch Costs in London (2026 CAD)

Pricing in London follows broader Ontario trends, but the shorter building season (May through October) compresses contractor availability. That means pricing can creep higher if you're booking late. Most experienced builders have their summer schedules locked in by March.

Deck Installation Costs

For a standard 12x16 deck (192 sq ft) in pressure-treated wood, expect to pay roughly $5,760–$10,560 installed. Bump that to composite and you're looking at $9,600–$16,320. For detailed breakdowns on popular deck sizes, check out our guide on 12x16 deck costs in Ontario.

Porch & Screened Porch Costs

Porches cost more because you're adding a roof structure, and potentially screens, electrical, and ceiling finishes.

• Open covered porch: $60–120/sqft depending on roofing material and complexity
• Screened porch: $70–140/sqft — add screens, framing for screen panels, and often a finished ceiling
• Three-season room: $100–180/sqft — insulated windows, upgraded flooring, possible heating

A 12x16 screened porch in London typically runs $13,440–$26,880 fully installed. That's a significant investment, but you're adding genuine livable space to your home for roughly six to seven months of the year.

Cost note: Composite and PVC decking hold up best in London's climate. Pressure-treated wood is cheaper upfront but needs annual sealing to fight moisture and road salt damage. Over a 10-year span, composite often costs less when you factor in maintenance. For a deep comparison of composite brands available locally, see our best composite decking brands in Ontario guide.

Screened Porch vs Open Deck: Which Handles London Winters Better?

This is the question London homeowners wrestle with most. Both options have trade-offs in a climate that swings from +30°C summers to -25°C winters with heavy snow in between.

Open Deck: Pros and Cons for London

Advantages:

• Snow falls through gaps in deck boards (with proper spacing) or slides off — less structural load
• Faster to build, lower cost
• Easier to shovel and maintain in winter
• Better airflow means boards dry faster after rain, reducing rot

Disadvantages:

• Completely exposed to weather — unusable in rain, bugs, or extreme heat
• Freeze-thaw cycles are brutal on wood decking. Water seeps into grain, freezes, expands, and cracks the surface
• Footings must extend below the frost line (36–60 inches in London) or you'll get frost heave — the deck literally shifts as the ground freezes and thaws

Screened Porch: Pros and Cons for London

Advantages:

• Usable from roughly late April through October — bugs, light rain, and wind aren't factors
• Roof protects the floor surface from direct snow and UV, extending material life
• Adds resale value. Screened porches are highly desirable in Southwestern Ontario

Disadvantages:

• Roof must be engineered for snow loads — this adds cost and complexity
• Ice dams can form where the porch roof meets your home's main roof if insulation and ventilation aren't handled correctly
• Screens can be damaged by ice and heavy wind; some homeowners swap to storm panels for winter
• Higher upfront cost by 40–60% compared to an open deck of the same size

The bottom line: If your budget allows it and you want maximum usability, a screened porch is the stronger investment in London. An open deck is the better call if you primarily entertain in July and August and want to keep costs down.

Three-Season Room Options

A three-season room goes a step beyond a screened porch. Instead of mesh screens, you get insulated glass windows (often sliding or removable panels) that keep the space comfortable from April into November — sometimes longer with a portable heater.

What a Three-Season Room Includes

• Insulated glass panels (single or double-pane)
• Finished ceiling and interior-grade flooring
• Electrical for lighting, outlets, and optionally a ceiling fan
• Optional baseboard or wall-mounted heater
• Vapor barrier and insulation in the floor assembly

Cost in London

Expect $100–180/sqft installed for a properly built three-season room. A 12x16 space runs $19,200–$34,560. That's a meaningful renovation, but it essentially adds a new room to your home.

Important distinction: A three-season room is not a four-season sunroom. A true four-season room requires HVAC integration, full insulation to code, and often a building permit as a habitable addition. Three-season rooms are lighter-duty — great for morning coffee in April and evening reading in October, but not designed for January use.

Use PaperPlan to visualize different decking materials on your own home before committing — it's especially helpful when you're deciding between a deck surface for an open build versus flooring options for an enclosed porch or three-season room.

Finding a Builder Who Does Both Decks and Porches

Not every deck contractor builds porches. And not every general contractor builds decks well. You need someone who understands both — the structural framing of a deck and the roofing/enclosure work of a porch.

What to Look For

• Roofing integration experience. A porch roof ties into your home's existing roofline. Done poorly, this creates leaks and ice dams. Ask to see past porch projects — specifically the roof-to-house connection
• Footing knowledge for London soils. London sits on a mix of clay and loam. Footings that aren't dug deep enough will heave. Your builder should know the local frost line and dig to a minimum of 48 inches (many go to 60 in London)
• Permit familiarity. A good London-area builder pulls permits as part of the job and knows the local inspection process
• Material sourcing. Builders who regularly work with composite brands like Trex, TimberTech, or Fiberon typically get better pricing and have installation experience that affects warranty coverage

Red Flags

• Won't pull a permit or suggests you "probably don't need one"
• Can't show photos of completed porch projects (only decks)
• Quotes footings at less than 36 inches deep
• No discussion of snow load or drainage planning

If you're comparing builders across Southwestern Ontario, our articles on best deck builders in Cambridge and best deck builders in Hamilton cover what to expect from top contractors in nearby cities.

Getting Quotes

Get three quotes minimum. But more importantly, make sure each quote covers the same scope. A deck quote should break out:

• Materials (brand, product line, color)
• Footings (number, depth, type — sonotube vs helical piles)
• Framing (wood vs aluminum deck framing)
• Railings, stairs, and skirting
• Permit fees and inspection coordination
• Timeline and payment schedule

For porches, add roof structure, screening or glazing, electrical, and ceiling finish to that list.

Permits for Porches vs Decks in London, Ontario

London's Building Department requires permits for most outdoor structures. Here's the general rule:

Decks: A building permit is typically required if the deck is more than 24 inches above grade or exceeds 100 square feet. Even ground-level decks may need a permit depending on proximity to property lines and whether they're attached to the house. For a deeper look at how attached and freestanding decks differ in the permitting process, see our guide to attached vs freestanding deck permits in Ontario.

Porches and screened porches: Almost always require a permit. The roof structure triggers building code requirements for snow load, wind load, and connection to the existing home. If you're adding electrical, that's a separate electrical permit.

Three-season rooms: Require a building permit. Depending on the design, London may classify this as a home addition, which triggers additional zoning and setback requirements.

Permit Costs and Timeline

• Deck permits in London typically cost $200–500 depending on project value
• Porch and addition permits can run $400–1,000+
• Processing time is usually 2–4 weeks, but can stretch longer in spring when application volume spikes
• Your contractor should handle the application, drawings, and inspection scheduling

Contact London's Building Department directly for the most current requirements. Municipal rules can change, and your specific lot may have additional restrictions (easements, heritage overlays, tree protection).

Pro Tip: Book Early

London's building season runs May through October. Contractors start filling their schedules in January and February. If you want a porch or deck built for summer use, get your quotes in winter, sign a contract by March, and have your permit application submitted before April. Waiting until May often means you won't get on a good builder's schedule until mid-summer — or even the following year.

For a realistic look at project timelines, our backyard renovation timeline guide breaks down what to expect month by month.

Frequently Asked Questions

How much does it cost to build a screened porch in London, Ontario?

A screened porch in London typically costs $70–140 per square foot installed in 2026. For a standard 12x16 space (192 sq ft), that puts the total between $13,440 and $26,880 CAD. The wide range depends on roofing complexity, screen panel quality, flooring material, and whether you include electrical. Composite or PVC flooring adds cost upfront but eliminates the annual sealing that wood requires in London's freeze-thaw climate.

Do I need a permit to build a deck in London, Ontario?

In most cases, yes. London requires a building permit for decks over 24 inches above grade or larger than 100 square feet. Attached decks almost always need a permit because they connect to your home's structure. Even smaller or ground-level decks may require one depending on your lot's zoning. Contact London's Building Department with your specific plans — it's a quick call and can save you from costly issues at resale.

What's the best decking material for London's climate?

Composite and PVC decking perform best in London's harsh winters. They resist moisture absorption, won't crack from freeze-thaw cycles, and don't need annual sealing. Pressure-treated wood is the most affordable option but requires yearly maintenance to prevent splitting and rot — especially with exposure to road salt and snowmelt. Cedar falls in the middle: naturally rot-resistant but still needs periodic sealing. For a full material comparison, read our best composite decking in Canada guide.

Can I use a screened porch in winter in London?

A standard screened porch is not designed for winter use in London. Mesh screens don't stop cold air, and the space will be at outdoor temperatures. Some homeowners install removable storm panels or vinyl enclosures for shoulder-season use (extending into November or starting in March), but true winter comfort requires a three-season room with insulated glass or a fully insulated four-season addition. If winter use is a priority, budget for the upgrade upfront — retrofitting later costs more.

How far apart should I space deck footings in London?

Footing spacing depends on your deck's size, load, and design, but most London builders space footings 6 to 8 feet apart for standard residential decks. More critical than spacing is depth — footings in London must extend below the frost line, which is typically 48 to 60 inches in this region. Footings that are too shallow will heave as the ground freezes and thaws, causing your deck to shift, crack, and eventually become unsafe. Always confirm footing depth with your contractor and the building inspector.