Screw Piles vs. Concrete Piers: What’s Better for Decks in Winnipeg?

The foundation of any deck is critical to its long term durability and support. Manitoba’s soil conditions and harsh winters make foundations more vulnerable to movement and frost damage than in many other parts of Canada making the decision between concrete piers (sonotubes) and screw piles (helical piles) even more important. 

Why Foundations Matter in Winnipeg

Winnipeg sits on expansive clay soil with deep frost penetration, which means the ground can shift significantly during freeze-thaw cycles. In these conditions, a strong deck needs a foundation that either goes well below the frost line or resists frost movement. Improperly installed deck foundations can cause the deck to move, crack, or lift over time.

Concrete Piers for Decks

In this method, contractors dig holes below the frost line (typically around 4 feet), place a form tube, and pour concrete to support the deck posts.

Pros of Concrete Piers

• Proven and widely used foundation method: Concrete piers have been the traditional way to support decks for decades.
• May be more economical: Materials are less expensive, however there is an added cost for labour and soil removal. For small decks with good soil conditions, concrete piers are still a good option. 
• No specialized installer required: Concrete piers can be installed by general contractors while helical piles require specialized machines and certified installers which can limit contractor options.

Cons of Concrete Piers

• More vulnerable to frost heave: When moisture freezes in the soil, it can push the concrete upward and cause decks or stairs to shift. If the pier isn’t deep enough below the frost line, your deck can move or become uneven over time.
• Digging is required: Concrete piers require digging large holes and removing soil from the site.
• Require curing time. Deck builders need to wait for concrete to cure before building. In Winnipeg’s short deck building season, these delays can slow down the project compared to screw piles which can be used immediately.

Screw Piles (Helical Piles)

Screw piles, also called Helical Piles, are steel shafts with helical plates that are screwed deep into the ground well below the frost line using a machine. 

Pros of Screw Piles:

• More resistant to soil movement and frost: Screw piles are installed deep below the frost line which makes the deck more resistant to frost heave. This means a more stable deck long-term. They are measured by a torque reading to guarantee it hits solid ground allowing a warranty to be offered on movement.
• No waiting to build: While concrete footings require digging holes, pouring concrete and waiting for it to cure before construction can begin, Screw piles can be installed in a few hours. Builders can often start building the deck the same day, speeding up the whole project.
• Minimal disruption to landscaping: Concrete foundations require large holes and removing soil. Screw piles are simply screwed into the ground with a machine, which means less digging, less mess and less damage to your yard.
• Can be installed almost any time of year: Because there’s no concrete involved, screw piles can even be installed in cold or slightly frozen ground, which isn’t possible with traditional concrete footings.
• Long-lasting and low maintenance: Screw piles are usually made from galvanized steel, which helps protect them from rust and gives them a long lifespan with little maintenance.

Cons of Screw Piles

• Upfront cost per pile can be higher: Screw piles require steel piles and specialized installation equipment, which may increase upfront costs, but labour, excavation and delays for curing can narrow the price difference
• Access for a machine is required

Which Is Better for Winnipeg Decks?

Both concrete piers and screw piles can work for a deck foundation, but Winnipeg’s climate makes frost movement a serious concern, making screw piles an increasingly popular choice for decks and sunrooms. If you’re building a deck in Winnipeg and want the most stable long-term foundation, screw piles are often the safer choice. Talk to your local Winnepeg deck builder if you’d like more information.