Guide · Decks and porches
Deck permits in Northumberland County.
There are two different size limits in the municipal deck guides, and they do different jobs. One decides whether you need a permit. The other decides whether your footings have to go below frost. Mixing them up is the most common mistake on a deck project, and it is an expensive one.
Two numbers, two jobs
Search for deck rules in Ontario and you will see 108 square feet and 592 square feet quoted as though they were alternatives. They are not. Hamilton Township’s guide prints both, in two different sections, because they govern two separate questions.
Clear the first one and you may not need a permit. Clear the second one and you may not need frost protection. A deck can easily clear one and not the other.
The permit exemption
10 m²
108 sq ft
All three conditions have to be true at once:
● Under 108 sq ft in area
● Not attached to any other structure
● 24 inches or less above finished grade
The frost exemption
55 m²
592 sq ft
All four conditions have to be true at once:
● Under 24 inches high
● Not attached to any structure
● Supports no roof, pergola or trellis included
● Not more than 592 sq ft in area
A 300 square foot ground level deck, freestanding, with no roof, needs a permit and does not need frost protection. Both at once. That combination surprises people.
Where the line sits
The threshold is not the same in neighbouring towns.
This is the part that catches people who read one municipality’s guide and apply it to a property in the next one. Cross a boundary and the exemption can disappear.
Cobourg
The Town’s deck guide states that a deck will generally require a building permit, and sets out no size exemption of its own. Any porch requires a permit. A patio at grade generally does not, unless it interferes with an existing structure.
The Town’s permit page frames the general trigger as a building area over 10 square metres. Because the deck guide carries no carve-out, the sensible step on a Cobourg property is to confirm with the Town rather than assume the exemption applies. Applications go through Cloudpermit.
Port Hope
Same starting position. A deck will generally require a permit, any porch requires one, and a patio generally does not.
Port Hope’s guide carries the 592 square foot frost exemption and the full guard height table, but no size exemption from the permit itself. It also has the longest list of approvals needed before you apply, which is covered further down.
Hamilton Township
The clearest statement of the three part permit exemption: under 108 square feet, not attached to any other structure, and 24 inches or less above finished grade. Miss any one of the three and you need a permit.
Porches always require a permit. The guide still advises contacting the office to confirm, which is worth doing because it prints both size limits.
Clarington
The most specific, and the only one of the four publishing a figure. Freestanding decks under 108 square feet need no permit. Anything over 108 square feet needs one whether it is attached or not. An attached deck needs a permit where the dwelling is more than 0.60 m, about 2 feet, above grade.
The permit is $160.86 per deck. Three drawings are usually required and three inspections are required. Uploads must be PDF. Zoning applies regardless of size or height, so setbacks still bind an exempt deck.
Fee schedules and guides get revised. Treat the figures here as the published position at the time of writing and confirm the current ones when you apply.
Guards
Twenty-four inches is the number that changes the build.
Above 24 inches of walking surface height you need a guard. That single trigger also tends to pull in a permit, and in most of these guides it pulls the footings down below frost at the same time. One step up in height changes three things at once.
Two details that get missed. Balusters have to stop a 100 mm sphere, four inches, passing through, which rules out a lot of decorative spacing. And where a bench is built into the guard, the height is measured from the bench surface, not the deck, so a built-in bench raises the guard behind it.
Cobourg’s guide points railing details at Supplementary Standard SB-7.
Footings
Most of the cost is under the boards.
Where a deck or porch is attached to a dwelling, or where it needs a guard, the published minimum is 48 inches, 1.2 m, below grade. Cobourg’s guide puts it as piers extending a minimum of 1.2 m below grade and adds a limit the others leave out: a pier must not extend more than three times its own width above grade.
This is the requirement that is cheapest to meet on day one and most expensive to fix later. Ground here freezes and lifts. A deck sitting on shallow pads will move, then rack, then need taking apart, and by then the guard and the stairs are attached to it.
Decking is a finish and it can be replaced. Footings are structure and they cannot, not without dismantling what sits on them.
The drawings
What the application actually has to show.
Homeowner-prepared drawings are accepted in Clarington provided they are drawn to scale and accurately describe the construction. A designer who is not the homeowner has to be qualified. Either way the content is the same, and an incomplete set is the usual reason an application sits.
Site survey
● Where the deck sits relative to the house
● Deck dimensions
● Distance to every property line
● Other buildings and the septic location
Plan and section
● Footing and foundation construction
● Pier location, depth, size and spacing
● Framing sizes, spans and spacing
● Height from finished grade
● Method of attachment to the dwelling
● Guards, stairs and handrails where they apply
Alongside the drawings: the completed Application for a Permit to Construct or Demolish, Schedule 1 Designer Information or a commitment to review, an Applicable Law checklist, and confirmation from Planning that the setbacks are met. Note the septic requirement. On a rural lot the site plan has to identify where the bed is, and that is also the thing most likely to move the deck.
Before you apply
Approvals that have to be in hand first.
Port Hope publishes the fullest list, and it is the part of the process that decides whether a deck project is two weeks of paperwork or two months. Depending where the property is and what is being built, these come before the building permit application rather than after it.
Planning
Planning reviews the proposal before you apply, checking zoning compliance including setbacks, lot coverage and height. Zoning binds a deck even where a permit does not.
Conservation authority
Ganaraska Region Conservation Authority approval is needed where the building is on or near an environmental constraint area or one with fill restrictions. A separate body with its own clock.
Septic
Septic system approval comes from Northumberland County, not the municipality. Relevant on any rural lot, and the reason the bed has to appear on the site plan.
Heritage
A Heritage Approval Application is required for changes to a designated property. A front porch on a designated house is exactly the case this applies to.
Entrances
An entrance permit from the Municipality on a municipal road, or an entrance and setback permit from the County or the Province on a county road or provincial highway.
Soil, in Port Hope
A Port Hope Area Initiative soil inspection. Specific to Port Hope and easy to miss, since nothing about a deck suggests a soil step.
Inspections
The inspection you skip is the one you dig back up.
Several inspections are required and the municipality issues the list specific to your project. Cobourg asks for at least 24 hours of notice before work moves from one stage to the next, on 905-372-1005, and states plainly that failing to have work inspected may mean having to uncover and expose it. Clarington requires three, booked on 905-623-7876, with calls before 3pm getting next-day attendance.
Where a contractor is doing the work, the property owner remains responsible for making sure the contractor calls for every inspection. Approvals have to be granted before the next phase starts. On a deck that means the footings get seen before anything is framed over them, which is the whole reason the stage exists.
Starting without a permit is unlawful. Both Cobourg’s and Port Hope’s guides state that the permit fee may be doubled, and Port Hope adds that you may be ordered to stop work, to remove all structures, or to uncover completed work, and may be prosecuted.
Four approvals, four clocks
A deck on a serviced town lot is usually one permit and one set of drawings. A covered porch on a designated heritage house near a watercourse on a rural property is four separate bodies, each wanting something slightly different, each with its own queue.
Run in sequence they stack. Run together, with the drawings prepared so each body gets what it needs the first time, they overlap. That is most of the difference between a project that moves and one that sits.
We have been building decks, porches and outdoor structures across Northumberland County since 1999, and we handle the permit work on the projects we build.
Frequently Asked Questions
Which size limit decides whether I need a deck permit?
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The 108 square foot one. The permit exemption, where a municipality publishes one, needs three things true at once: under 108 square feet, not attached to any other structure, and 24 inches or less above finished grade. The 592 square foot figure you will also see is a different rule. That one governs frost protection, not permits, and it carries a fourth condition about supporting no roof. A deck can need a permit and not need frost protection, or the reverse.
Is the deck permit exemption the same in Cobourg, Port Hope and Clarington?
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No, and this is the trap. Clarington publishes an explicit exemption for freestanding decks under 108 square feet, and requires a permit for anything larger whether attached or not. Hamilton Township publishes the same three part exemption. Cobourg’s and Port Hope’s deck guides both say a deck will generally require a building permit and set out no size exemption of their own. On a Cobourg or Port Hope property the safe move is to confirm with the municipality rather than apply a neighbouring town’s rule.
How deep do deck footings have to go?
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Where the deck or porch is attached to a dwelling, or where it needs a guard, the published minimum is 48 inches, 1.2 m, below grade. Cobourg’s guide states it as piers extending at least 1.2 m below grade and adds a limit the other guides leave out: a pier must not extend more than three times its own width above grade. Frost protection is only waived where the deck is under 24 inches high, attached to nothing, supports no roof including a pergola or trellis, and is no more than 592 square feet.
How high does a deck guard have to be?
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Guards are required once the walking surface is more than 24 inches above grade. Up to 5 feet 11 inches of height the minimum guard is 36 inches, 900 mm. From 6 feet to 32 feet 8 inches it is 42 inches, 1070 mm. Above that Port Hope’s table gives 59 inches. Balusters have to stop a 100 mm sphere passing through, and where a bench is built into the guard the height is measured from the bench surface rather than the deck.
Does a covered porch need a building permit?
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Yes. Cobourg, Port Hope and Hamilton Township all state that any porch requires a building permit, with no exemption by size or height. A roof also rules out the frost protection exemption, which specifically excludes anything supporting a roof, a pergola or a trellis. So a covered structure means a permit and footings below frost, every time.
What does a deck permit cost?
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Clarington publishes $160.86 per deck. Cobourg and Port Hope do not publish a deck specific figure in their deck guides, so the fee comes from the municipal building permit fee schedule. Fee schedules are revised periodically, so confirm the current number when you apply rather than relying on a figure found online.
What happens if I build a deck without a permit?
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Both Cobourg’s and Port Hope’s guides state that the permit fee may be doubled. Port Hope adds that you may be ordered to stop work, to remove all structures, or to uncover completed work, and may be prosecuted. Starting construction without the necessary permits is unlawful. The practical cost is usually the uncovering, because on a deck the footings are the part nobody can see once the frame is on.
Do I need conservation authority approval for a deck?
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Possibly, and it comes before the building permit application rather than after it. Port Hope’s guide lists Ganaraska Region Conservation Authority approval as something you may need first, where the building is on or near an area with environmental constraints or fill restrictions. That is a separate body with its own process, so it is worth establishing early whether the land is regulated.
Do I have to show the septic system on the deck drawings?
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Yes, on a property that has one. The site survey has to show other buildings and structures including the septic system, and Hamilton Township’s sample site plan calls out identifying the septic location specifically. In practice this is also the thing most likely to move a deck, since the bed and its clearances are fixed and the deck is not.
Can I draw the deck plans myself?
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In Clarington, yes. Homeowner prepared drawings are accepted provided they are drawn to scale and accurately describe the construction, and a standard deck construction drawing can be used as the basis. A designer who is not the homeowner has to be qualified. Whoever draws them, the set has to carry the footing and pier details, framing sizes and spans, height from grade, the method of attachment to the house, and guard, stair and handrail details where they apply.
Planning a deck or a porch?
Tell us the size, the height above grade and whether you want a roof on it. We will tell you which approvals it needs and come back with a fixed price.
Request a Free Estimate (905) 376-5585Keep reading
For what a deck costs and what we build, see decks and porches. On a designated property, read heritage permits in Port Hope. On a rural lot, septic and wells covers the approval that moves the deck. Near the lake or a valley, see building on the shoreline. We work across Cobourg, Port Hope and Clarington, and the rest of the guides are here.