A desk review and one site visit can rank an infill lot’s risk and buildable area, if the screen covers the ground, the neighbours and the approval path.
Parcels get overlooked for reasons. A downtown lot that has stayed a surface parking lot for a decade, a corner left vacant between two older buildings, an under-used block behind a commercial strip: some of these are waiting for the right owner, and some have a problem that the last three owners found. A one-day screen tells an owner which kind they are looking at before money goes into design.
The screen below is written for an owner or developer and their engineer.
• History. Check past land uses through historical air photos, fire insurance plans and city directories. Former service stations, dry cleaners and fuel storage are common on older commercial lots and can trigger provincial requirements before redevelopment, such as a Record of Site Condition under O. Reg. 153/04 when an Ontario property changes to residential use.
• Ground. Review surficial geology and any nearby borehole records. Note fill, organic soils, a shallow water table or seismic site class. Any one of these can change the foundation type for a mid-rise building; a shallow water table also decides whether below-grade parking is realistic.
• Neighbours. Walk the property lines. Record the age, height and likely foundation type of every adjacent building. Excavation next to older shallow foundations needs shoring and monitoring, and party walls or encroachments can delay a start. Note whether an adjoining lot could be assembled: added frontage can change what the parcel will carry.
• Site services. Ask the municipality for the size and condition of water, sanitary and storm mains in the street and any known capacity limits. A six-storey building on a lot served for a single storefront often needs new connections. • Code path. Confirm which building code applies and whether it allows a single exit stair at the height proposed. British Columbia has permitted single-exit-stair residential buildings up to six storeys since August 27, 2024, and Vancouver since January 20, 2026. Under the National Building Code, which most provinces adopt, new single-exit multi-unit residential buildings are still limited to two storeys. On a narrow lot, that difference often decides the unit count per floor, or whether a mid-rise fits at all. If the building may be prefabricated, confirm the units will be certified to CSA A277, the standard for factory-built housing, and check whether the municipality has a streamlined permit path for them.
Approval path. Compare the scheme against the as-of-right envelope for units, height and lot coverage, and note what would need a development permit, a variance or a rezoning. Check council agendas for pending bylaw changes. In Calgary, lot coverage on R-CG lots dropped from 60 to 55 per cent on August 4, 2026, and only applications already in process kept the old rules. After this month’s local elections, check whether the incoming council has signalled changes to infill zoning or development charges.
• Rank and decide. Score each item as clear, manageable or significant. Two significant items on one parcel, or an approval path that needs a rezoning, are a reason to price them before purchase, not after.
The common objection is that a one-day screen is too shallow to rely on. For design, it is. Its job is narrower: to rank risk and approval time well enough to decide whether to spend on a full investigation, and to put a number on the risks an owner is about to buy.
The parcels that sat empty longest are often the ones where this screen pays most, because the problem the last owner walked away from is usually findable, and usually priceable.
Want a second opinion on an infill parcel? Talk to the PRI Team.
Contact Our Team.
We would love to hear more about you and the project that you have in mind.
“After working on both sides of development, the best projects are those with client collaboration.”
Nola Kilmartin, MUP, RPP, MCIP
Vice President, Property & Buildings
nola.kilmartin@priengineering.com