How close to my side lot line can an Ottawa deck sit?

The answer depends on your deck's height above grade, which yard it sits in, and which of Ottawa's two active zoning by-laws is more restrictive for your lot. Both Zoning By-law 2008-250 and Zoning By-law 2026-50 apply to permit applications deemed complete on or after March 11, 2026, and the most restrictive provisions from each by-law govern.

What the zoning rules say

For a deck with a walking surface no higher than 0.6 metres above adjacent ground, both by-laws agree: in the interior side yard and rear yard there is no minimum setback and no maximum projection. In the front yard or exterior side yard, the deck may project the greater of 2 metres or 50 per cent of the required yard, but no closer than 1 metre to the property line.

For any other deck, meaning one whose walking surface is higher than 0.6 metres above grade, the rules are different. Zoning By-law 2026-50 section 204 sets a minimum setback of 1 metre from any lot line and a maximum projection of 2 metres into the yard. Zoning By-law 2008-250 section 65 Table 65 row (6) sets the same figures in that situation. Because both by-laws land on the same numbers here, the result is a 1 metre minimum setback from the lot line in the interior side yard.

Two additional provisions in 2026-50 are worth checking for your lot. First, for residential buildings, a deck projecting into the rear yard above the first floor is subject to restrictions based on lot depth: no projection at all on lots 23.5 metres deep or less, and a maximum projection of 1.2 metres on lots between 23.5 and 30.5 metres deep. Second, on lots zoned N1 to N6, a deck or balcony within 1.5 metres of an interior side lot line and above the first floor requires a 1.5 metre high opaque screen facing that lot line.

There is also a question of how a deck counts toward soft-landscaping minimums. Zoning By-law 2026-50 defines a deck as hard landscaping, so it does not count toward any soft-landscaped area your zone requires. Whether a standalone deck counts toward accessory-structure area limits is not settled in the by-law wording, so confirm that point with the City.

A few things to confirm before you finalise the design: the exact zone your lot sits in, the required yard depths in that zone, the lot depth, and whether any rear-yard setback provisions in 2026-50 are among the portions still under appeal at the Ontario Land Tribunal. The City can tell you which rules are in force for your specific address.

On the permit side, a deck attached to the house with a walking surface more than 600 mm (24 in.) above adjacent grade requires a building permit. The permit drawings must show the deck dimensioned to all property lines, so the setback is documented before a single post goes in.

Before work starts, have three things on paper: a complete set of scaled, dimensioned drawings that show the setbacks and the permit number issued by the City, and a written contract that sets out the full scope and the price.