Drawings are where the permit sails through or gets bounced. The OBC sets the minimum; the municipal plans examiner sets the expectations. Here is how to hit both on the first submission.
Division C 1.3.1.3 Sentence (5) says the review clock only starts when the application is complete. "Complete" is not subjective — it means every required drawing, specification, schedule, and fee is in the package. A missing site plan, a missing wall section, a window U-value that does not match the energy package, a structural callout without a sealed detail — any of them stops the clock the same way. The reviewer opens the package, flips through it in three minutes, and if anything looks soft they hand it back with a list. That list is the difference between a 10-business-day turnaround for a house (the legislated maximum under Table 1.3.1.3) and a six-week real-time slog. The top rejection reasons in Ontario are the same every year: setbacks not dimensioned to the property line, building height not dimensioned from grade to peak, wall section missing the vapour barrier or R-value callouts, LVL or steel beams without a manufacturer span chart, and mechanical drawings missing the principal ventilation fan capacity. Every one is catchable at the drafting table. The reviewer is not trying to fail you — they are measuring the package against a checklist. Hand them a package that ticks every box and the permit is a signature.
Nine times out of ten the drawing that sends a package back is the site plan, because homeowners and small-scale builders think of it last. A site plan is not "a sketch of the building on the lot." It is a scaled drawing of the entire property — every lot dimension, every existing and proposed building, every setback dimensioned to every property line, driveways, septic/well, easements, and a north arrow. Almost always at 1:200. The reviewer uses it to verify zoning (setbacks, lot coverage, FSI), spatial separation per OBC 9.10.15, and drainage per OBC 9.14. If the site plan does not have dimensions to every property line, the reviewer cannot do any of those, and the package fails on one drawing. The fix is painless — a Surveyor's Real Property Report (SRPR) is often already in the property's closing paperwork, and the proposed work overlays onto it. Print it, dimension it, include it.
Ontario permit drawings are metric, scaled, and printed at a specific ratio. A 1:50 drawing means one millimetre on paper equals fifty millimetres in the field — so a wall 2.4 m tall draws as 48 mm on paper. 1:100 is half the size (a large-building plan). 1:200 is site plan scale — a 40 m lot draws as 200 mm wide. Wall sections and structural details go tighter: 1:20 for a typical wall section, 1:10 for a connection detail. Two rules matter more than people think. First, print the scale in the title block AND include a scale bar. PDFs get printed on the wrong paper size all the time, which changes the ratio silently — a drawing marked 1:50 can print at 1:56 and every dimension you scale off it is wrong. The scale bar prints at the same ratio the drawing does, so the reviewer can measure against the bar and ignore the notation. Second, write dimensions on the drawing, do not make the reviewer scale. Scaled dimensions are approximate; written dimensions are contractual. Every rejection notice quotes this back.
Ontario's system gives homeowners a real option. For a house-class project on a lot you own and intend to live in, you can submit drawings under the Owner's Affidavit — you sign a form stating you are the owner, you drew the package, and you accept responsibility for it. The drawings still have to meet the same technical bar as a designer's. But as soon as the project falls outside OBC Part 9's prescriptive tables, the affidavit is no longer enough. A long-span LVL that exceeds the 9.23.12 tables needs either a manufacturer span chart or a P.Eng stamp. A steel beam needs a P.Eng stamp. A retaining wall over 2 m needs a P.Eng stamp. Prefabricated trusses come with the manufacturer's engineered shop drawings. Commercial, multi-unit residential, and change-of-occupancy projects always require a registered designer with a Building Code Identification Number (BCIN) and a Schedule 1 filed with the package — there is no homeowner path. The right call is usually easy: adding a deck, finishing a basement, building a garage — the homeowner path works. Moving a bearing wall, spec'ing a long beam, anything commercial — pay the designer and move on.
OBC 9.36 Energy Efficiency applies to every new house, addition, and material renovation. The permit application has a checkbox for the compliance path — prescriptive (Supplementary Standard SB-12) or performance (HOT2000 energy model). Whichever path you pick, the drawings and specifications have to match. Prescriptive SB-12 is a lookup — the table tells you the wall R-value, roof R-value, window U-value, and equipment efficiency required for your climate zone, and your wall section, window schedule, and mechanical drawings have to meet those numbers. Performance is a modelled calculation — a HOT2000 report shows the whole building meets the target, and the drawings back up the inputs. The most common rejection here is silly: the applicant checks the prescriptive box but the windows they specified do not meet the SB-12 table for their zone. The form says one thing; the window schedule says another. The reviewer catches it in two minutes. Before you submit, hold the SB-12 table against your window schedule, insulation callouts, and HVAC spec sheets. Either they all match or you change something.
The fastest thing a homeowner or small builder can do to avoid a bounce is book a pre-consultation meeting with the plans examiner before drafting starts. Most Ontario municipalities offer this free. Bring a rough sketch, lot dimensions, and a one-paragraph scope. The examiner will tell you which drawings they expect, whether anything needs a designer, and any local amendments on top of the OBC minimum. Fifteen minutes at the counter saves weeks. Two more habits catch most of what is left. First, build a cover sheet with a drawing index — A0 cover, A1 site plan, A2 foundation, A3 floor plans, A4 elevations, A5 sections, S1 structural, M1 mechanical, P1 plumbing — so the reviewer can count the set on page one. Second, include a specifications page — written callouts for concrete strength, lumber species and grade, insulation type and R-value, vapour barrier permeance, window U-value and SHGC, sheathing thickness, fastener schedule. Drawings show geometry; specs pin down materials. When both are in the package and they agree, the permit turns around in the Table 1.3.1.3 minimum and the job starts on schedule.