The R1-7 Snapshot
R1-7 is a common residential zoning designation in London. Its primary detached ARU hurdle is the 35% maximum lot coverage screen, which is lower than many other residential zones and can eliminate a lot before builder pricing even starts.
How To Calculate The 35% Envelope
Lot coverage is the percentage of your lot area covered by buildings. That means the house, garage, qualifying sheds, and proposed detached ARU all matter. If your lot is 4,000 sq. ft., the 35% screen would point to 1,400 sq. ft. of total allowable footprint before any other zoning or site constraints are layered in.
Total Footprint / Total Lot Area = Lot Coverage %
Smaller Plans Usually Get A Cleaner First Look
If you are close to the 35% limit, you may need a smaller detached ARU layout, a reduced footprint, or removal of existing structures to create room. London's current interim ARU rules limit each ARU to a maximum of 2 bedrooms, so any larger catalogue or builder plan may need to be adapted before it is promoted as a London ARU option. That is one reason CMHC ADU 01 is often the cleaner first-pass conversation than a larger multi-bedroom concept.
R1-7 Math Is A Screen, Not An Approval
If your math shows you close to the 35% line, the next step is not overconfidence. It is a closer review of footprint, setbacks, lot layout, and servicing. Use this page as a preliminary fit check, then confirm the details through the City's zoning and permit process.
FAQ
Common questions, answered plainly
What is the max lot coverage for R1-7 in London?
The research file highlights a 35% maximum lot coverage screen for R1-7 zoning. Homeowners should confirm the current rule and calculate their lot-specific footprint before relying on it.
Does a detached ARU count toward lot coverage?
Yes. In London, a detached ARU is a building and its footprint is added to the total lot coverage calculation.
What structures usually count in the R1-7 lot coverage math?
Homeowners should usually assume the main house, attached or detached garage, covered additions, and the proposed ARU footprint all matter in the first-pass screen. Smaller accessory structures can still affect the review depending on how they are classified, so it is safer to measure generously before assuming there is room left.
If my property is close to 35%, is the project dead?
Not always. A close result usually means the next step is a tighter site review, not an automatic no. Some homeowners end up shifting to a smaller plan, reducing the footprint, removing an existing structure, or revising the layout before they decide whether to spend on drawings.
Why do smaller ARU plans tend to work better in R1-7?
Smaller plans usually create less pressure on lot coverage, setbacks, circulation, and servicing. They also fit more naturally with London's current interim two-bedroom screen, which is why a compact layout often gets a cleaner first review than a larger multi-bedroom concept.
Should I price builders before I confirm the lot coverage screen?
Usually no. If the lot is already tight on coverage, early builder pricing can create false momentum around a plan that may need to shrink or change. Screening the lot first helps homeowners spend time and money on options that have a better chance of fitting the site.
Check The Lot Before You Adapt The Plan
Use the Backyard Audit to see whether the property looks worth deeper R1-7 review before you spend on drawings or builder deposits.
Start The R1-7 Audit