If your tree splits into two or three trunks at the base, don’t just measure the biggest one and call that the diameter. Metro Vancouver bylaws don’t agree on how to combine multiple stems into a single legal DBH. The same tree can land above the protected threshold in one city and below it in the next. New Westminster’s formula differs most, and its bylaw is the only one in this comparison that prints a worked number, so you can check your own math against it.
New Westminster Squares Its Stems
New Westminster’s Tree Protection and Regulation Bylaw No. 7799, 2016, sets the protected threshold at s.2.1(jj): a DBH above a set size, or a combined DBH above it across the two largest trunks. DBH itself is measured above the base. The protected size is 20 cm.
For a multi-stem tree, New Westminster squares each stem’s diameter, sums the squares, and takes the square root of that total, rounded to the nearest cm. Every other municipality checked for this post (Vancouver, Burnaby, Richmond, Surrey, Port Moody, the District of North Vancouver, White Rock and Maple Ridge) adds stems together instead. Some take the largest stem plus a fraction of the rest, and others sum the two or three biggest trunks. None squares the stems.
The Bylaw’s Own Worked Example Gives 25 cm
New Westminster’s bylaw prints a worked example for the square-root formula. Three stems measuring (in cm) 12, 14 and 17 give a legal DBH of 25 cm, because the square root of (12 squared plus 14 squared plus 17 squared) equals 25 cm.
Get it wrong on a multi-stem tree near New Westminster’s size threshold and you can put the tree on the wrong side of that line.
Vancouver and Burnaby Add Up Their Largest Stems
Vancouver’s Protection of Trees By-law No. 9958 protects a tree at 20 cm DBH or more. Vancouver’s s.2.2 leaves out a tree under 20 cm, except for a replacement tree or a tree that is part of a hedge. Vancouver measures DBH at 1.4 m. For a multi-stem tree, the DBH is the combined diameter of the two or three largest stems.
Burnaby’s Tree Bylaw 1996 No. 10482 sets its threshold by species and site: one DBH for a conifer and another for a broadleaf off a development site, or a lower one on a lot under a current development application. Confirm the sizes with Burnaby. Burnaby measures DBH at 1.3 m, and a multi-stem tree’s DBH is the sum of the three largest stems.
Richmond Weights Its Stems While Surrey and Port Moody Sum Three
Richmond’s Tree Protection Bylaw No. 8057 defines a protected tree by a set DBH, measured at 1.4 m. The protected size is 20 cm (tree that could reach 4.5 m in height, outside an environmentally sensitive area in Schedule E); any size (land identified as an environmentally sensitive area in Schedule E). For a multi-stem tree, Richmond takes 100% of the largest trunk plus 60% of each additional trunk, so the smaller trunks count for less.
Surrey’s Tree Protection Bylaw, 2006, No. 16100 sets its threshold at 30 cm DBH or more at 1.4 m, or a stump of 35 cm or more. A multi-stem tree’s DBH there is the sum of the three largest stems.
Port Moody’s Tree Protection Bylaw, 2026, No. 3531, s.3.1, sets one DBH threshold on any lot, dropping for six named species or in specified sensitive zones. Confirm the sizes with Port Moody. A multi-stem tree’s DBH is the cumulative total of the three largest stems.
North Vancouver District, White Rock and Maple Ridge
The District of North Vancouver’s Tree Protection Bylaw 7671, 2012 sets no diameter floor for a “protected tree” in a streamside, steep slope or wetland area. It does set a floor for a “large-diameter tree” that isn’t otherwise protected. In the District of North Vancouver, DBH is measured at 1.3 m on the uphill side, and a multi-stem tree’s DBH is 100% of the largest stem plus 60% of each additional stem, up to six stems, each rounded up to the nearest cm. Richmond uses the same weighted method.
White Rock’s Tree Protection Bylaw, 2021, No. 2407 protects a tree with a DBH of 20 cm or more, measured above the highest point of natural grade. A multi-trunk tree there is sized by cumulative total: two trunks combine both, and three or more trunks combine the three largest.
Maple Ridge’s Tree Protection and Management Bylaw No. 8045-2026, s.3.1, protects a tree at 20 cm DBH or more, or a stump over 25 cm at grade, measured at 1.40 m. A multi-stem tree’s DBH is the sum of the three largest stems, illustrated in the bylaw’s own Figure 2.0.
Borrowed Formulas Cause the Mistakes
An easy error is a borrowed rule. Someone compares notes with a neighbour in Richmond, or reads a permit guide written for Burnaby, and applies that city’s sum to a New Westminster tree. The measuring height moves too: 1.3 m in Burnaby and the District of North Vancouver, 1.4 m in Vancouver, Richmond, Surrey and Maple Ridge. Take the tape to the height and formula in the bylaw for the lot the tree stands on.
Reports for Metro Vancouver Permits
We prepare ISA Certified Arborist reports for tree removal permit applications in Metro Vancouver. On a multi-stem tree, the stem diameters go through that municipality’s own formula before the DBH goes in the report. The tree bylaw guide has the full comparison across Metro Vancouver. We confirm availability for your address before we quote. Send us yours.