Home additions in Whitby

In the R1 to R3 zones of By-law 1784, a by-law dating from 1960, the answer is 20%. Here is what Schedule A asks of an interior lot, with the deemed 90% figures beside it:

Note: coverage figures are our arithmetic on the minimum lot; your lot is probably bigger, and Schedule A warns that not every amendment is folded into it. A house with no garage needs 5.0 m on one side.

Much of Whitby isn't zoned R1 to R3. Many newer subdivisions sit in zones such as R1A* and R2A*, written into the by-law by 1990s amendments, with their own numbers. There, a one-storey house may cover 40% of the lot, and a one-storey rear addition needs a 7.5 m rear yard. Your zone is on the Town's zoning map, and we read the exact clause before drawing anything.

It can save you a variance. Ontario now treats a by-law's minimum setback as 90% of what it says, on urban residential land, so a 6.0 m rear yard becomes 5.4 m without asking anyone. The rule doesn't cover the Greenbelt, or the areas O. Reg. 254/23 sets aside: within 120 m of a wetland, a river or stream valley or the Great Lakes shoreline, and within 300 m of an active railway. In Whitby that excludes many ravine lots and the lakeshore. It also does nothing for lot coverage; 20% is still 20%.

Over the limit, you apply for a minor variance. The fee is $1,526, with $930 more to CLOCA if the lot is in its regulated area and $313 to Durham Region Health on a private septic system. Five appointed members hear applications at a monthly meeting on the third Thursday. The Town's page says to file three weeks ahead, but its own 2026 table sets deadlines about five weeks out: Monday 9 November for the 17 December hearing. Neighbours within 60 m get notice at least 10 days before, and you post the Town's sign on your lawn for the same 10 days. After the decision, anyone with an interest has 20 days to appeal to the Ontario Land Tribunal. With no appeal, a 17 December decision becomes final and binding once that window closes on 6 January 2027, and only then do we file for the building permit.

At $22.37 per m², a 40 m² family room off the back is a permit fee of $894.80, our arithmetic. In Whitby we've added up rather than out: West Lynde went from one storey to two. The closest rear extension we've finished is Greenwood in Toronto, some 40 km west; it came with new foundation waterproofing and weeping tile.