How the 10-Metre Height Limit Actually Lands on a Sloped Burnaby Lot

On a flat Burnaby lot, the 10.0 m maximum building height is a number you can mark on a ruler. On a sloped lot — Capitol Hill, Buckingham Heights, Cariboo, the upper Burnaby Heights blocks — it is a calculation, and the calculation can swing the effective roof line by a foot or more depending on where the surveyor takes the points. We have watched permits stall for two weeks over a 20 cm dispute. We have watched architects redraw a roof because the surveyed average came in lower than the design assumed. This post is the version of the conversation we wish we could have with every owner before they engage a designer.

It is a companion to the longer hillside custom homes hub, which covers the full picture of building on slope.

What "average grade" actually means

The City of Burnaby's R1 schedule, like most municipal zoning schedules in BC, measures the 10.0 m maximum height against average grade — not against the lowest point on the lot, not against the highest, but against the average of the surveyed natural grade taken at points around the perimeter of the proposed building.

The exact methodology is set in the City of Burnaby building permit submission requirements and is referenced against the BC Building Code definitions. A BC Land Surveyor (BCLS) takes elevation readings at the corners of the proposed building footprint — sometimes at intermediate points along long faces — and reports the arithmetic mean. That mean is the datum from which the 10.0 m measurement starts.

On a level lot, every reading is roughly the same, so the average and any individual reading are interchangeable. On a sloped lot, the readings can range over two metres or more, and the average sits somewhere in the middle.

A worked example

Imagine a 15 m × 12 m building footprint on a lot that drops 2.4 m from the back property line to the front. The four corners might survey at:

• Upslope rear-left: 102.40 m
• Upslope rear-right: 102.30 m
• Downslope front-left: 100.10 m
• Downslope front-right: 100.00 m

The arithmetic average is 101.20 m. The maximum allowed building height puts the highest point of the roof at 111.20 m.

From the upslope corners (at 102.30–102.40 m), the roof is 8.80 m above grade — comfortable. From the downslope corners (at 100.00–100.10 m), the roof is 11.20 m above grade — visually taller than the City would allow if you measured from there.

That is the rule working as designed. The upslope grade and the downslope grade share the height budget. The downslope side of the house can stand taller than 10 m above local grade, because the upslope side stands less than 10 m. The total budget is the average.

Where this catches owners off guard

Three places, every time:

1. The roof "loses" a foot

An architect designs a three-storey house with a 9 ft main floor, a 9 ft second floor, an 8 ft third floor, and a low-slope roof. On paper, the wall-to-roof dimension is comfortably under 10.0 m. The surveyor produces the average grade, and it lands 30 cm lower than the architect assumed because the downslope corners pulled it down. The roof needs to come down 30 cm — usually from the third floor, because the lower floors are already framed in the drawings.

The fix is to commission the survey before the architectural sections are drawn, not after. We push this hard with every Burnaby slope client.

2. The neighbour's house looks taller

Two adjacent Burnaby lots, both with the same 10 m height limit. One owner builds on the upslope half of their lot, where local grade is high — the house looks short. The next-door owner builds in the same lot configuration but the prior owner had filled the lot to level the front yard, raising the average grade. The new house, designed to exactly the same 10 m, looks taller. Both are legal. Both are at the maximum. Only one looks like it.

This is the conversation that drives the most neighbour disputes during construction. The bylaw doesn't promise the new house will look the same height as the existing one — it promises 10 m above that lot's average grade, which is specific to that lot's surveyed surface.

3. Cut-and-fill regrading

A homeowner thinks they can lower the downslope side of the lot during excavation and "raise" the average grade — making 10 m feel taller. Burnaby's bylaw catches this directly: the average grade calculation is taken from existing natural grade, not from finished grade after excavation or fill. Cutting the lot down does not give back ceiling height. Filling it up does not either. The average is locked at the natural surface as it existed before any work.

The BC Building Code definitions of grade line up with this — what counts is the undisturbed surface, with reasonable allowances for the existing site conditions.

How to lock the calculation in early

We walk every hillside client through the same sequence:

1. Engage a BCLS land surveyor before the architect produces sections. A topographic survey with 0.5 m contours and the perimeter grade points marked on it is the foundation document. Without it, the architect is guessing.
2. Get the average grade calculated in writing. The surveyor produces a one-page calculation showing the perimeter points and the resulting mean. We submit this to the City planner during pre-application review.
3. Confirm the calculation with the City planner. A 15-minute call with Burnaby's building department, with the calculation in front of them, surfaces any methodology disagreement before drawings are sealed. We have done this for every hillside permit we have submitted in the past three years.
4. Design the building section to the confirmed average. Now the roof line can be drawn with confidence, the third-floor ceiling height can be locked, and the trades downstream know what to build.

Doing this work upfront costs roughly two weeks and one surveyor invoice. Discovering a grade dispute after the drawings are sealed costs months and a redesign.

What about the rear-building exception?

Burnaby's R1 schedule sets a 10.0 m height limit on principal front buildings and a lower limit (typically 7.5–8.0 m) on rear buildings such as coach houses or detached secondary dwellings. The same average-grade methodology applies to both, but the calculation is taken across the individual building's footprint, not the lot as a whole. A rear coach house on the downslope half of a lot will have its own, lower, average grade — and a correspondingly lower roof datum.

This is one of the few places where a sloped lot delivers an advantage for a multi-building configuration: a coach house at the bottom of the lot doesn't fight the principal house for height budget. They are calculated separately.

What to ask before you write an offer

If you are evaluating a lot to buy, three questions get you most of the way to knowing whether the height calculation is going to be friendly or hostile:

• What is the cross-fall across the building envelope? If the answer is "two metres or less", you're probably going to be fine. Three metres and up, the calculation starts pulling the average down hard.
• Is there fill on the lot? Previous fill counts as part of natural grade if it was placed before the bylaw datum, but recent fill placed to flatten the front yard typically doesn't. A geotechnical inspection can usually tell.
• Where will the building footprint sit? A footprint that hugs the upslope side of the lot will have a higher average than one that spans the full grade change. Sometimes a smaller, upslope-side house gives you more ceiling than a larger one that reaches downhill.

Read next

• The hillside custom homes hub — the full picture of building on slope.
• Foundations & geotech — how the foundation choice interacts with the height calculation.
• Drainage & retaining walls — the water side of the same problem.
• Building a custom home on the Capitol Hill / Burnaby Heights hillside — what the height calculation looked like on a specific east-facing build.