Calculation Lab
The exam calculations, worked step by step
Each method shows where the values are in the 2024 OBC, the steps in order, worked examples and the mistakes that cost marks.
- worked methods
- 12
- worked methods
- exams that ask for them
- 5
- exams that ask for them
- to read, no account needed
- Free
- to read, no account needed
Last updated
All 12 methods
- Method 1Spatial separation calculationsWork out exposing building face area, limiting distance and the allowed glazed or unprotected opening area using the 2024 OBC tables.HouseSmall Buildings
- Method 2Occupant load calculationsHow to work out occupant load from Table 3.1.17.1, then use it for stair width, exits, door swing and septic daily design flow.HouseSmall BuildingsOn-site Sewage Systems
- Method 3Footing and foundation sizingSize Part 9 strip and column footings step by step: Table 9.15.3.4 lookups, veneer and masonry add-ons, long joist spans, water table and thickness.HouseSmall Buildings
- Method 4Joist, rafter and beam spansRead the Part 9 span tables for joists, rafters, built-up beams and lintels, including the specified snow load that picks the roof column.HouseSmall Buildings
- Method 5Stair geometry calculationsWork out risers, rise, total run, landings, headroom and tolerances for Part 9 stairs under the 2024 Ontario Building Code, with worked examples.HouseSmall Buildings
- Method 6Guard and handrail checksWork out when a guard is required, how high guards and handrails must be, how many handrails a stair needs, baluster spacing and guard loads.HouseSmall Buildings
- Method 7SB-2 fire-resistance rating calculationsRate masonry walls by equivalent thickness and framed walls, floors and roofs by the SB-2 component additive method, with worked examples.HouseSmall Buildings
- Method 8SB-12 energy efficiency calculations for housesPick the SB-12 zone and compliance package, check the window-to-wall ratio, add up effective RSI layers and apply airtightness substitutions.HouseSmall BuildingsHVAC - House
- Method 9Plumbing sizing calculations for a houseAdd up fixture units, size a house drain, stack, trap arm and vent, and turn roof area and SB-1 rainfall into a storm load, step by step.On-site Sewage SystemsPlumbing - House
- Method 10On-site sewage calculationsSize a Part 8 septic system step by step: daily design flow, septic tank capacity, trench length, fill and filter bed areas, and raised bed clearances.On-site Sewage Systems
- Method 11HVAC and ventilation calculations for housesSize principal and supplemental fans, make-up air, natural ventilation areas, hearth extensions and clearances under OBC Part 9, in L/s and mm.Small BuildingsHVAC - House
- Method 12Building area, grade and height in storeysWork out grade, the first storey, building height in storeys, building area, mezzanine limits and facing streets, then apply Part 9 and Part 3 limits.HouseSmall Buildings
By exam
The methods each exam asks for, and a link to drill its calculation questions (free account).
House9 methods
Drill House questions
The methods paraphrase the 2024 Ontario Building Code and cite the article each value comes from; check the code itself before you rely on a number for a real project.