Ontario Building Code 2024
Code-backed answers
for every residential build.
Twenty-four free Ontario Building Code calculators for carpenters, contractors, and homeowners. Verified by a Red Seal Carpenter, imperial-first with tape-measure fractions, every result tied to an OBC clause. Print-ready for the permit office or the inspector on site.
✓ Verified by a Red Seal Carpenter
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✓ OBC 2024 (Jan 16 2025 amendment)
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✓ Imperial-first fractions
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✓ Free forever
The tools
Pick by project stage.
Every tool cites the exact OBC clause it draws from and produces a branded PDF with your inputs, the result, and the verification stamp.
Start here
Every project starts with one of these two. Permit first if you're planning. Violation lookup if you just failed an inspection.
→ Do I need a permit?
14 project types covered — deck, addition, basement finish, shed, pool, HVAC, plumbing, electrical, fence, demolition, change of use. Returns Required / Exempt / Check with Municipality with the OBC clause driving the decision.
OBC Division C 1.3.1
🔎 Violation Reverse-Lookup
Failed an inspection? Search a plain-English violation or an OBC clause number. Get the exact clause, what it takes to pass, why the rule exists, and a direct link to the calculator that solves it. 43 common failures covered.
All OBC 2024 clauses
Structural framing
Span tables, headers, studs, and fasteners — the bones of every Part 9 residential build.
Framing Span
Maximum allowable spans for floor joists, ceiling joists, and rafters. SPF / Hem-Fir / D.Fir-L at 12″ / 16″ / 24″ o.c.
OBC 9.23.4.2 + Tables A-1 / A-7 / A-14
Beam Span
Built-up 2× wood beams and steel W-shapes, indexed by supported joist length. Cross-checks beam capacity against the joists above.
OBC 9.23.4.2-H/I/J + 9.23.4.3
Header Sizing
Lintel over a door or window. Opening width plus what sits above → smallest built-up 2× or glulam header that passes.
OBC 9.23.12.3 Tables A–D
Stud Height & Spacing
Maximum stud height by size, spacing, and load. Covers interior partitions and loadbearing walls up to 3 storeys.
OBC Table 9.23.10.1
Nail & Fastener Schedule
Every framing connection — floor, wall, roof, sheathing. Nail size, count, spacing, technique, and corrosion requirements.
OBC Table 9.23.3.4 + 9.23.3.5
Foundation Wall Sizing
Cast-in-place concrete, block, ICF, surface-bonded — minimum thickness by unbalanced backfill and wall height. Footing size + vertical reinforcement included.
OBC 9.15.4.2 + Tables -A/-B
Stairs & life safety
Every home renovation touches at least one of these. Inspectors check them first.
Stair Calculator
Rise, run, headroom, and width for private / public / service stairs. Pass-or-fail checks on every dimension.
OBC Section 9.8
Stair Stringer & Handrail Details
Nosing projection, stringer effective depth after cut, handrail height + extensions + graspability. The stair details you cut and install.
OBC 9.8.4.2 + 9.8.9.4 + 9.8.7
Guard Height & Load
Where guards are required (600 mm drop trigger), minimum height (900 vs 1070 mm), 100 mm sphere rule, climbability, and specified loads by location.
OBC 9.8.8
Egress Window Checker
Bedroom egress: clear opening area, minimum dimension, sill height, and basement window well. Pass/fail with every OBC sentence called out.
OBC 9.9.10.1
Smoke & CO Alarm Placement
Describe your house; get required alarm count, locations, type, and interconnection rules with OBC clauses driving each.
OBC 9.10.19 + 9.32.3.9
Basement Headroom Checker
Is your basement tall enough to finish? Per-room pass/fail against the 2.1 m rule + the 75/25 relief for dropped beams and ducts.
OBC 9.5.3.1 + Table 9.5.3.1
Plumbing Fixtures Required
Kitchen sink, water closet, lavatory, tub/shower, laundry — required count per dwelling unit + the 5-bedroom second-bathroom trigger + suite rules.
OBC 9.31.4
Decks & foundation
The outdoor build. Frost depth, footings, soil bearing — what holds everything up.
Deck Footing Depth
Ontario region → minimum frost-line depth. Tributary area + soil type → required footing diameter and concrete volume per footing.
OBC 9.15.1.3 + 9.4.2
Deck Ledger Attachment
Required lag-bolt or through-bolt spacing by joist span and fastener choice. Flashing detail + edge distances + the ledger-to-brick-veneer warning.
OBC 9.23.9 + AWC DCA-6
Septic System Setback
Minimum setback from septic tank, leaching bed, holding tank, or Class 1 privy to wells, surface water, property lines, buildings, and slopes.
OBC 8.2.1.5 + 8.2.1.6
Envelope & barriers
The stuff behind the drywall that keeps a house healthy — air sealing, vapour control, climate-zone rules.
Vapour & Air Barrier Rules
Pick an assembly (wall, basement, attic, cathedral, flat roof, floor-over-unheated, slab) → required barrier specs, warm-side placement, recommended materials, climate-zone notes, common mistakes.
OBC 9.25.3 + 9.25.4 + 9.25.5
Ventilation Rate
Principal exhaust capacity (L/s + CFM) by dwelling size, HRV requirement per SB-12, per-room bathroom/kitchen fans, makeup-air trigger.
OBC 9.32.3 + SB-12
Attic Ventilation
Required net free vent area (1:300 with vapour barrier, 1:150 without), 50/50 soffit/ridge split, cathedral unvented alternative.
OBC 9.19.1.2 + 9.25.2.5
Planning & paperwork
The stuff that has to happen before the first cut. Permit scope, drawings, Part 11 reno compliance.
Required Drawings Checklist
Project type → exact drawings needed for the permit package (site plan, foundation, elevations, structural, energy) with scale hints and rejection-reason notes.
OBC Div C 1.3.1.3
Renovation Scope Triggers
Basic Repair / Basic Renovation / Extensive Renovation / Change of Use — which Part 11 path applies, what gets triggered, what relief is available.
OBC Part 11 + Part 10
Site & fire separation
Where the building sits on the lot. Critical for additions, infill, and anywhere close to a property line.
Running a crew? Check the WSIB & safety tools too.
Seventeen free Ontario workplace safety tools — WSIB premiums, fall protection, scaffold inspection, PPE requirements, confined space, noise exposure, and more. Same contractor, different questions. Browse WSIB/OHSA tools →
How it works
Pick, enter, print.
1
Pick a tool
Start with Do I need a permit? if you are not sure. Every tool is free and runs in your browser.
2
Enter your inputs
Species, spacing, span, room type — whatever the tool needs. Imperial-first with tape-measure fractions; flip to metric in Settings if you prefer.
3
Print or share
Every tool has a Print / PDF button that produces a branded sheet with your inputs, result, OBC clause, and verification stamp. Hand it to your inspector.
Who verified this
Built for the job site, not the classroom.
Every value in every tool is traced to a specific clause in the Ontario Building Code 2024 Compendium, current to the January 16, 2025 amendment. Span tables, footing depths, fastener schedules, egress dimensions — all reproduced directly from the code book with source comments in the module files so any carpenter or inspector can audit the math.
Verification stamps are pulled from a single source-of-truth log, so when a clause is re-checked, every downstream tool updates its date automatically.
Red Seal CarpenterOntario Certificate of Qualification. Years of residential framing on site.
OBC 2024 CompendiumDivision B Part 9 (Housing and Small Buildings), with clause citations on every output.
Inspector-ready printoutsBranded PDF with inputs, result, clause, verification date, QR link back to the tool.
Free for Canadians, foreverNo paywall. No sign-up. No ads inside the calculators.
FAQ
Common questions.
Are these tools free?
Yes. Every OBC tool on this page is free forever — no sign-up, no paywall, no ads inside the calculators themselves. Use them on your phone, tablet, or desktop from the job site or office.
What version of the Ontario Building Code do these tools use?
All tools reference the Ontario Building Code 2024 Compendium (Division B Part 9 for housing and small buildings), as amended January 16, 2025. Each tool cites the exact clause or table it draws from, so you can verify any value against the official code book.
Who built these and who verified them?
The tools are verified by a Red Seal Carpenter (Ontario Certificate of Qualification). Every calculator shows the verification date in its footer and carries a single-source-of-truth verification log so updates are transparent.
Can I use the printouts for a building permit package?
The branded PDF from each tool shows your inputs, the calculated result, the OBC clause cited, and the verification stamp — which is enough supporting detail for most permit-office conversations. Municipal requirements vary; always confirm your local building department's exact package before submitting.
Are the values in imperial or metric?
Both, always. The display defaults to imperial with tape-measure fractions (for example "14′ 1 5⁄16″") because that is how most Canadian carpenters read a tape. The metric value is shown alongside as the authoritative OBC reference. You can flip the default in Settings.
Do these tools replace an engineer or inspector?
No. They reproduce prescriptive OBC values for common residential conditions, which is what Part 9 publishes. Anything outside those conditions — engineered point loads, heavy snow zones, structural alterations to existing buildings, large buildings, commercial occupancies — needs a professional review. The tools flag when you are leaving the prescriptive path.
What does the permit decision tree do?
You pick a project type (deck, basement, addition, shed, pool, HVAC, plumbing, electrical, fence, demolition, or change of use), answer two or three scope questions, and the tool tells you whether a building permit is likely required or exempt — with the OBC Division C 1.3.1 clause driving the decision and what to do next. It is the recommended starting point.
Does ToolFluency have tools outside of the OBC?
Yes. ToolFluency is a complete platform with 200+ free tools covering construction, finance, business, health, kids, music, and more — plus a paid Business tier for invoicing, payroll, and Canadian tax compliance. The OBC suite is one of several free-forever toolsets. Browse everything →