Deck footings come in eight main types: poured concrete, sonotube, concrete pier, helical pile, ground screw, precast deck block, buried post, and concrete slab.
Nobody admires a footing, so you have probably never given yours a thought. Your deck looked perfectly level last September. Then April arrived, the railing felt loose, and the patio door started to stick. After more than a decade building decks in this region, I can tell you those symptoms almost always begin at the bottom of the hole.
Read on to find out which footing suits your soil, your budget, and your municipality.
What Are Deck Footings?
Deck footings are the buried concrete or steel supports that carry your deck’s weight down into stable soil, below the depth where winter frost can lift them. They are also the one part of your deck you will never see again once the backfill goes in.
The easiest way to understand them is to follow the load. Weight travels from the deck boards into the joists, along the beam, down the post, and finally into the footing. The footing then spreads that weight across a wide patch of soil, much the way a snowshoe spreads yours. Without that spreading, the post punches straight into the ground, and it takes your deck with it.
Why Deck Footings Matter
Footings decide whether your deck lasts thirty years or three.
Frost Heave Protection
Water expands roughly nine percent when it turns to ice, so wet soil doesn’t just harden over winter, it swells. A footing that stops short of the 1.2 metre frost line rides up with that swelling, then settles again in spring, rarely back where it started. Do that three or four winters running and your deck no longer sits level.
A Solid Connection to Your House
Your ledger board bolts the deck to the wall with half-inch fasteners at 32-inch centres. That joint tolerates almost no movement. Each freeze-thaw cycle works the bolts looser, and failed ledger connections cause a large share of deck collapses.
Load Capacity for Hot Tubs, Pergolas and Snow
A filled hot tub with four adults pushes past 5,000 pounds in one small area. Standard framing tables assume a 2.0 kilopascals snow load and nothing more. So if a hot tub or a pergola is even a maybe for you, the quote stage is when we need to know, not next spring.
Passing Your Footing Inspection
Footing depth and size fail more inspections than anything else in a deck build. When they’re right, your framing and final visits pass on schedule, and nothing gets taped to your front door.
Resale Value When You Sell
Buyers order home inspections, and a sinking deck turns into a price reduction. Footings built to depth keep your deck out of the inspector’s notes entirely.
What are the Most Common Types of Deck Footings
1. Poured Concrete Footings
The concrete footing is the widened base at the bottom of the excavation that transfers the deck load safely into the supporting soil. Under the Ontario Building Code, the footing must provide enough bearing area to match the soil’s load-bearing capacity, which is typically around 0.40 m² where the allowable soil bearing pressure is 75 kPa.
It must also rest on undisturbed native soil, not loose backfilled material, because disturbed soil can settle over time and cause the deck to shift, sink, or become uneven.
| Pros | Cons |
| Highest load capacity of any footing typeBearing area sizes to any soil valueAccepted by every Ontario municipalityRoughly $150 to $300 per footing installed | Excavation leaves spoil to haul awayConcrete cures before framing startsStony glacial till slows the augerHole stays open until the inspector visits |
Best for: almost every attached deck in this part of Ontario. If your deck bolts to the house and sits more than two feet off the grass, this is the footing we quote first.
2. Ground Screw Footings
Ground screws are the light-duty relatives of engineered piles, and adjustable versions sit on the shelf at most hardware stores. A heavy drill drives them in, no concrete required. Capacity is the limitation.
Consumer models typically rate near 4,000 pounds each, against 10,000 pounds or more for a professional system. Homeowners use “ground screw” and “helical pile” as though they mean the same thing. Your building department does not, which is worth knowing before you order a pallet of them.
| Pros | Cons |
| No digging and no concrete on siteFraming can start the same afternoonThreaded collar adjusts for levellingAround $200 each if you install them | Rated near 4,000 pounds per screwSized for 4×4 posts, not 6x6Approval varies between municipalitiesHard going in stony or root-filled soil |
Best for: low freestanding platforms, sheds, and fence lines. Your building department will want to sign off on them first, and we won’t put them under a deck that attaches to the house.
3. Sonotube Footings
Many homeowners think the Sonotube adds strength to the footing, but its job is simply to act as a concrete form. Once the concrete hardens, the tube has no structural role. What matters is the smooth, round concrete pier it creates.
In clay soils, rough or uneven surfaces give frost more to grip as the ground freezes and expands. A smooth concrete column reduces frost heave, helping the footing stay stable through repeated freeze-thaw cycles.
| Pros | Cons |
| Smooth shaft resists frost gripSets plumb and to a consistent gradeStocked at every local building supplierTakes a poly wrap and clear stone backfill | Adds form cost to every footingThe tube itself carries no loadNeeds bracing during the pourTapered hand-dug holes defeat the purpose |
Best for: any poured footing in clay-heavy ground. If puddles still sit on your lawn two days after a spring rain, you have clay, and your footings need that smooth column.
4. Concrete Pier Footings
The terms footing and concrete pier are often used interchangeably, but they refer to different parts of the foundation. The footing is the widened concrete base below ground that spreads the deck load, while the pier is the vertical concrete column that supports the beam above.
Under the Ontario Building Code, a residential concrete pier must be at least 10 inches (254 mm) in diameter. The code also limits how much of the pier can extend above grade. As a general rule, the exposed height cannot exceed three times the pier’s diameter, so a 10-inch pier should have no more than 30 inches of exposed concrete above ground.
| Pros | Cons |
| Holds wood clear of soil and standing waterAccepts standard galvanized post saddlesA detail every Ontario inspector knowsPoured in the same visit as the footing | Exposure capped at three times the widthFooting pad still needs sizing separatelyAn 8-inch pier punches into soft groundCalls for 15 MPa concrete, not bagged mix |
Best for: raised and walkout decks where the finished surface sits well above the yard, and the posts need a dry, solid base to land on.
5. Helical Pile Footings
Helical piles are galvanized steel shafts with helix plates welded near the tip, driven by hydraulic equipment until the torque reading confirms they’ve reached soil that can carry the load. There’s no cure time and no pile of dirt on your lawn.
They suit lots with narrow side-yard access, which is why they pair well with expert elevated deck installation across York Region. One local detail matters first: the Town of Newmarket requires a Professional Engineer to design helical pile footings.
| Pros | Cons |
| Framing starts the same day they go inTorque reading verifies capacity on siteReaches through fill to competent soilInstalls in shoulder season and light frost | Engineer’s design adds $500 to $1,500Mobilization charge hurts small jobsRoughly $200 to $350 per pileCan refuse early on a buried boulder |
Best for: soft ground, awkward access, retrofits under existing decks, and shoulder-season builds when concrete won’t cure reliably.
6. Precast Concrete Deck Blocks
Precast concrete deck blocks are surface-mounted supports with built-in slots for deck posts or beams, making them a quick and affordable foundation option. Their biggest limitation isn’t strength but frost movement.
Because they rest directly on the ground instead of extending below the frost line, they can rise and settle as the soil freezes and thaws.
They work well for low, freestanding decks that can be re-levelled if needed, but they’re not suitable for attached decks, where ground movement can place stress on the ledger board and the house connection.
| Pros | Cons |
| Under $20 each at most suppliersNo excavation and no spoil to removeJack and shim it level in an afternoonWhole platform goes down in a day | No frost protection at any depthNot permitted under attached decksSmall bearing face sinks in soft soilLimits you to decks under two feet |
Best for: freestanding garden platforms under two feet high, set away from the house. If it lifts an inch over winter, you shim it in an hour and carry on.
7. Buried Post Footings
With buried post footings, the wooden deck post is set directly into the ground, often on top of a concrete footing. This method is still used for pergolas, arbours, and fences, where structural loads are relatively light.
However, it is generally not recommended for decks because prolonged contact with soil and concrete exposes the wood to moisture, increasing the risk of rot from the inside out.
Newmarket’s deck construction guidelines also require structural wood to be kept clear of ground contact, which is why this foundation method is better suited to our custom pergola, gazebo, and cabana construction rather than residential decks.
| Pros | Cons |
| Post resists sideways movement on its ownUses less concrete than a pier and padOne step instead of two on light buildsLong track record on fences and arbours | Wood rots where concrete traps moistureReplacement means dismantling above itCalls for ground-contact rated lumberRarely accepted under a raised deck |
Best for: pergola and fence posts in ground-contact rated lumber. A reasonable choice for a shade structure, a poor one for a raised deck.
8. Concrete Slab Footings
A concrete slab can sometimes serve as a deck foundation, especially when it’s specifically engineered to support heavy loads such as a hot tub or outdoor structure. However, most existing patio slabs are designed for foot traffic, not the weight of a deck.
Installing deck posts directly onto a standard 4-inch concrete patio without proper footings beneath can lead to settling, movement, and an uneven deck over time.
Before building on an existing slab, it’s important to confirm that it has the strength and foundation needed to safely support the structure.
| Pros | Cons |
| Spreads a hot tub’s weight over 60 sq ftDoubles as usable patio surfaceRemoves individual footing layoutHandles point loads a single pier cannot | Four-inch patio slabs rarely qualifyNo way to confirm what sits underneathCosts more than eight poured piersTub loads need an engineer’s design |
Best for: hot tub pads poured to specification, and engineered slab-on-grade bases for sunrooms or enclosed structures.
How to Choose the Right Deck Footing
The right deck footing comes from matching soil bearing capacity, deck load, frost depth, drainage, slope, and municipal requirements to the conditions in your own backyard.
Conditions vary street to street, and sometimes from one lot to the next. Your neighbour’s deck may sit on the dense glacial till this area is named for while yours sits on imported subdivision fill. Same street, different footing.
Deck Size and Weight
Larger decks concentrate more weight on each post, and height multiplies it. Hot tubs, roofs, and planters push past the 2.0 kilopascals assumption in the standard tables. On any professional pool deck installation services project, we size footings for those point loads from the first drawing.
Soil Type
Soil bearing capacity sets footing size before anything else. The code assumes 75 kilopascals, and some yards exceed that while others fall well short.
Clay Soil
Clay holds water, and water drives heave. It also grips concrete, so smooth forms and clear-stone backfill reduce how hard frost can pull.
Sandy Soil
Sand drains fast, but hole walls slough inward while you work. A belled base widens the bearing area and stops gradual settling.
Rocky Ground
Cobbles stop an auger cold, so we shift the hole or switch method. Solid bedrock removes the frost problem entirely, as it does on the Shield lots we handle for custom deck construction in Muskoka.
Loose or Filled Soil
A new-build yard tells this story well. Sod went down over imported fill last spring, nothing underneath has finished compacting, and footings have to reach through all of it.
High Water Table
Required bearing area doubles when the water table sits within one footing width below the bearing surface. That rule shapes most shoreline work we take on as custom deck builders in Keswick.
Sloped Properties
Sloped lots need stepped footings at different depths, and each one still reaches 1.2 metres down. Taller posts on the low side need diagonal bracing.
Frost Depth
Ontario’s frost line sits at 1.2 metres, roughly 48 inches, under Ontario Building Code section 9.12.2.2. Poor drainage pushes it deeper. Your inspector checks depth before you pour, because a footing at 40 inches heaves every single winter.
Drainage Conditions
Cold alone doesn’t cause heave; water does. A downspout emptying beside a post creates a problem inside one season, so we grade away from every footing and keep water moving. Where the space underneath gets used, professional deck waterproofing services finish the job.
Slope of the Yard
A sloping yard changes depth and layout both, and people measure from the wrong side. Depth is taken from the low side, not the high side. Steeper grades suit stepped platforms, which is where specialist multi-level deck design and layout turns an awkward yard into usable space.
Local Building Code Requirements
Rules shift between municipalities, and Newmarket adds a step homeowners rarely expect. You need a Zoning Preliminary Review before you can even apply for the permit. Decks between 0.6 and 3 metres high may encroach 3.6 metres into the rear yard, though never closer than 2.4 metres to the property line. We handle that paperwork as custom deck builders in Newmarket, Ontario.
Budget and Installation Timeline
Poured footings run roughly $150 to $300 each, helical piles $200 to $350, and most decks need four to eight. Concrete looks cheaper on paper. Add excavation, spoil removal, and three days of cure time, and piles often close the gap.
Do You Need a Permit for Deck Footings?
In Newmarket, you’ll generally need a building permit if your deck:
- Is attached to your house
- Covers more than 10 m² (108 sq. ft.)
- Is more than 600 mm (24 inches) above finished grade
Before construction begins, you’ll also need utility locates, and your deck footings must be inspected before the concrete is poured or backfilled.
| Stage | What happens | Typical timing |
| Zoning Preliminary Review | Setbacks and site plan reviewed | Goal of 5 business days |
| Building permit application | Drawings and footing details reviewed | 10 to 20 business days |
| Utility locates | Free, and required by law | 5 business days minimum |
| Footing inspection | Bearing capacity and size confirmed | Before you pour or backfill |
| Framing and final | Structure, guards and stairs checked | On completion |
If your property is close to a watercourse, wetland, or other regulated area, you may also need approval from the Lake Simcoe Region Conservation Authority before construction can begin.
6 Footing Mistakes That Turn Into a Rebuild
Every failed deck we’ve replaced showed at least one of these, usually two. None of them were the homeowner’s fault, because all of them happen below grade where nobody can see.
- Shorting the depth: Forty inches is not forty-eight, and the difference shows in the second winter. A tape measure to the top of the tube settles the question before anyone pours.
- Bearing on loose spoil: Augered soil falls back down the hole, and that material carries nothing. Footings must sit on undisturbed ground.
- Undersizing the diameter: An 8-inch tube gives you 0.35 square feet of bearing. It punches into soil instead of spreading weight across it.
- Skipping the bell: Pier spacing over 2,440 millimetres and coarse soil both call for a belled base. Belling costs far less than upsizing the whole column.
- Burying the post in concrete: Wood held tight against concrete rots from the inside out. A galvanized saddle holds the post clear and lets it dry between rains.
- Digging without locates: Ontario One Call reports that one in four residential digging projects damages buried infrastructure, and locates are free and legally required.
If your deck already slopes or bounces underfoot, the footings are almost certainly the cause. At that stage, expert deck removal and rebuilding services usually cost less than another round of patching.
How We Handle Footings at XP Decking
We start in your backyard rather than on a price sheet. Soil gets tested, grade gets measured, and we check how a machine would reach the work before quoting.
From there, the paperwork becomes our problem. We submit the zoning review, prepare the permit drawings, and order the locates, so you’re not chasing the Town.
On site, we dig or drive to spec and record the depth in writing. Then we book the footing inspection before any concrete goes in. That visit is the only independent check anyone will ever make on your footing depth and bearing.
You’re welcome to check all of it. Homeowners measure our holes, ask for the inspection sign-off, and photograph the work, and we’re glad when they do. We’d far rather you verified than lay awake wondering.
We built that process on our 15 years of hands-on construction experience, more than ten of them spent building decks through Ontario freeze-thaw winters.
Wondering what your own yard needs? Our number is (416) 333-2366, and we’ll come take a look at no charge.
Frequently Asked Questions
How many deck footings do I need?
Most decks need four to eight footings, spaced roughly every six to eight feet along each beam. The exact count comes from your joist span, beam size, and soil bearing capacity.
Does a floating deck need footings?
A floating deck sits unattached to the house, so the word describes the connection rather than the support underneath. Freestanding platforms under 600 millimetres can sit on deck blocks, while anything taller still needs footings below the frost line.
What size sonotube do I need for a deck footing?
Ten inches is the minimum diameter for a residential deck pier in Ontario. Wider pier spacing, hot tubs, or a roof overhead usually call for a belled base rather than a larger tube.
Can I reuse the footings from my old deck?
Reuse only works when the original depth and bearing can be verified, and on a deck built decades ago that is rarely possible. Most rebuilds we quote include fresh footings for exactly that reason.
