The short answer
Your town decides. The US model code exempts some small play structures, but local codes change the limits and zoning is a separate question. We have not checked your town, so ask your building department before you dig.
The short answer: it depends on your town, and we have not checked yours. We never tell anyone a fort needs no permit. What we can do is show you where the exemptions come from, where they stop, and what to have in your hand when you call. Our forts are freestanding, built on posts with no tree involved, so they are judged like any other small backyard structure.
Depends on where you build
Ask your building department first
Local approval not checked here. Many US jurisdictions exempt play structures up to about 200 sq ft (the IRC model), but thresholds, setbacks, HOA rules and zoning vary. Confirm with your local building department before you dig. The designer also has a Canada mode that uses NBC 2020.
What the US Model Code Exempts
Most US towns build on the International Residential Code (IRC) and then amend it. Section R105.2 of the 2021 edition lists work that does not need a building permit. We read the text as adopted by Grant County, Washington. Three items matter for a play fort.
- Accessory buildings on the ground. One-story detached accessory structures, up to 200 sq ft in area.
- Playground equipment. The list includes “swings and other playground equipment.”
- Low decks. Decks up to 200 sq ft that are not more than 30 in above grade and are not attached to a house.
The exemption is not a free pass
The same section says the exemption does not authorize any work done in violation of the code or of local laws. An exemption removes the paperwork. It does not remove the rule: setbacks, height limits and the rest still apply.
Where local rules go lower
Towns adopt their own amendments, and the numbers move. Lathrop and Beaumont, California, list “playhouses, and similar uses” and cap the floor area at 120 sq ft, well under the model’s 200.
Our free plans, side by side
We do not give a verdict per plan, because the verdict is your town’s. This table gives the two numbers a clerk will ask about: floor area and deck height.
| Preset | Floor area (sq ft) | Deck height |
|---|---|---|
| Toddler deck | 36 | 2 ft 6 in |
| Open tree fort | 64 | 5 ft |
| Fort with roof | 64 | 5 ft |
| A-frame fort | 64 | 4 ft |
| Fort with swing set | 64 | 5 ft |
| Open fort with swing set | 64 | 5 ft |
| Playhouse with swing set | 80 | 5 ft |
| Raised playhouse | 80 | 6 ft |
| Big fort 10x12 | 120 | 6 ft |
For every row the answer is the same: ask. A deck over 30 in, a roof, or a floor area near your town’s limit can each change which rule applies. The swing frame is a separate structure from the fort, so mention both when you call.
Zoning Is a Separate Question
The building code asks whether the structure is safe. Zoning asks where it may stand and how big it may be. Passing one does not pass the other.
- Setbacks. How far the structure must stay from each property line, and from your house.
- Height. Many towns cap the height of accessory structures.
- Lot coverage. How much of the lot your accessory structures may cover in total.
We do not print numbers for these because they differ by town and by zone, and we have not read yours. The local zoning office can answer all three in one call.
HOAs and deed restrictions
If you live in a community with an HOA, it can require approval before you build, set colors or heights, or ban elevated structures altogether. That approval is separate from the town. Read your covenants first, because an HOA can ask you to remove something the town would have allowed.
Canada: What the Cities We Read Say
The designer has a Canada mode that follows NBC 2020. The national code does not say whether a children’s fort counts as a “building,” so we treat its guard rules as a floor and never write that the code requires them for a fort. Permits are municipal, and the cities differ. This is what each city’s own page says. Check it again for your lot, because by-laws change.
| City | What we read | What still applies |
|---|---|---|
| Toronto | Building permit for an accessory structure larger than 10 m² (107 sq ft). | A 2016 Committee of Adjustment decision treated a treehouse as an accessory structure for zoning and cited a 4 m height limit and 5% lot coverage. Those figures come from that 2016 decision, and the by-law has been amended since. |
| Ottawa | Building permit for an accessory building over 10 m² (108 sq ft). | Height, setbacks and coverage come from the zoning by-law for your zone, which we did not read. |
| Calgary | A playhouse counts as an accessory residential building, with a permit above 10 m² (107 sq ft). | Even below that size the page asks for a floor no higher than 0.6 m (1.9 ft) above grade and a height of 4.6 m or less. Many raised forts are above that floor height. |
| Edmonton | The page lists tree houses under 2.0 m (6.6 ft) in height among minor structures that do not require permits. | Playhouses are accessory buildings: under 10 m², not attached, roof midpoint 4.3 m or lower, 0.6 m from the side and rear lines. |
| Winnipeg | Building permit for accessory structures over 10 m² (108 sq ft). | Development rules, heights and setbacks for a fort: we could not verify. |
| Halifax | Building permit at 20 m² (215 sq ft) or larger, or more than one story. | Below 20 m², a development permit applies for location and height. |
| Vancouver | The city lists building or altering a garage, shed or deck as work that normally needs a permit. | We could not verify the size exemption or the zoning limits. |
Our Canada mode says the same: local approval not checked, small accessory structures are often exempt at about 10 m², and height, setbacks, lot coverage and zoning still apply. The Calgary and Edmonton lines show how differently cities treat a raised platform.
What to Bring to the Counter
A short, clear package gets a short, clear answer. Before you call or visit the counter, gather these.
The paperwork
- A site plan. Your lot outline with the house, the fort position and the distance from the fort to each property line.
- A drawing. Plan and side views with the footprint, the posts and the overall height.
- The heights. Deck height above grade, guard height and roof peak, if there is a roof.
The questions
- Is a permit required for a freestanding play structure of this footprint and deck height?
- What are the setback, height and lot coverage limits for accessory structures in my zone?
- Does it matter that the swing set is a separate structure?
- Do I need to pay or file anything for an HOA, a utility locate or a survey?
Call 811 before any digging in the US, so buried lines are marked.
What our plan gives you
Pick a preset in the designer and adjust it to your size. The $29 plan includes the drawings and the materials list, which are the same documents a counter clerk usually asks to see. Heights matter at the counter, so read how high a treehouse should be first. To compare presets and prices, see our plans and what a fort costs. If you do not have a tree, you do not need one: see how it works without a tree.
Sources
Every number in this guide that does not come from our own treehouse designer was checked against these 9 documents, numbered in the order the text first cites them and read on Oct 25, 2026. 9 are playground guides and codes.
- 1City of CalgaryGarage, shed, gazebo and similar structures: Permits
- 2City of EdmontonDetached Garage, Shed, Gazebo
- 3City of Lathrop, CaliforniaWork Exempt from Permit
- 4City of OttawaDetached garages and sheds: Do I need a building permit?
- 5City of TorontoWhen Do I Need a Building Permit?
- 6City of VancouverWhen you need a permit
- 7City of WinnipegDetached garages and accessory structures
- 8Grant County, WashingtonExempt R105.2 (2021 International Residential Code, section R105) (2021)
- 9Halifax Regional MunicipalityDevelop your property
