Home additions and extensions

An addition is the only renovation that is really a small building project. It has its own foundation, its own structure and its own relationship to the zoning by-law, and it is the one job on this site where a design professional is not optional in practice. It is also where the ground under Ottawa starts to matter.

Step one: zoning before design. Check what the zoning by-law allows on your lot: the setbacks from each property line, the maximum lot coverage, the permitted height and the rear yard requirement. If the design needs relief from any of those, that is a minor variance application to the Committee of Adjustment, which adds months rather than weeks. A design produced before the zoning check is a design that may be thrown away.

Step two: confirm who will prepare and take responsibility for the permit drawings. Designer qualifications and any need for professional engineering depend on the building and proposed structure; verify the credentials with the City and relevant regulator.

Step three: investigate soil and foundation conditions for the actual lot. Ottawa properties can have sensitive clay, but depth and foundation design are site specific. Ask whether a geotechnical review is needed.

Step four: locates, excavation and the shell. Before any digging, a locate request through Ontario One Call is mandatory in Ontario, it is free, and it takes at least five business days. Then excavation, footings, foundation walls, waterproofing and backfill, followed by framing, roof, windows and the envelope. Getting the shell closed in before winter is the milestone that matters in this climate, and a project that reaches November without being closed in will lose weeks.

Step five: tie-in, services and finishes. The addition is tied into the existing roof, wall and floor structure, and the heating, electrical and plumbing are extended. This is usually where an older Ottawa house reveals that the furnace and the electrical panel were sized for the original footprint, and a panel upgrade or a second heating zone appears on the budget.

An addition schedule depends on design, zoning review, permits, structural work, weather protection and trade availability. Ask the designer and contractor for milestones based on the actual proposal.

For an addition quote, compare design and permit costs, foundation and soil work, structural tie-in, weather protection, services, finishes and site access. A measured design and site review are needed before a reliable price is possible.

Warranty, and where Tarion stops. The Tarion new home warranty covers newly built homes, including a contract home built for you on land you own, from a builder licensed by the HCRA, with one, two and seven year periods. It does not cover renovation of an existing home, and it excludes work and materials supplied by the homeowner (Tarion exclusions). An addition to a house you already live in is a renovation, so ask for a written warranty and check what it covers, particularly the envelope and the roof tie-in.

Who to hire and what to verify. General contracting is not licensed in Ontario. What is verifiable: the designer's BCIN or their OAA or PEO standing, authorization for compulsory electrical and plumbing trade work, ESA notification for the electrical, and the contractor's WSIB status, compulsory in construction with an exemption for occupant-retained work that does not extend to subcontractors (WSIB).

What to ask, and what to hold back. Has the zoning been checked, and does this need a minor variance. Who produces the permit drawings and what is their qualification. Is there a geotechnical report, and what foundation depth is designed. Who is the engineer of record. What is the schedule for closing in the shell. Is the panel or furnace being upgraded, and is that in the price. On payment, ask how the ten per cent statutory holdback will be retained and released for your contract under the 2026 annual-notice rules (Construction Act holdback in 2026). That holdback is your protection against a lien from a subcontractor the general did not pay.