BUYER'S GUIDE · 2026
How to Choose an ADU Builder in London, Ontario
A practical, honest guide to comparing ADU and garden-suite builders serving London and area — what to look for on pricing, permits, warranty and timelines.
What to compare before you hire
- Transparent pricing. Can you see a real starting price, or only "request a quote"? Published pricing is a sign of a builder confident in their costs.
- London permit experience. ADUs/ARUs live and die by zoning, setbacks and servicing. Choose a builder who knows the City of London process.
- Warranty. Ask whether detached units carry Tarion new-home warranty coverage, in writing.
- Custom vs pre-designed vs modular. Each suits different lots, budgets and timelines — make sure the builder's approach fits yours.
- Local, verifiable track record. Completed London-area projects you can actually see beat stock renderings.
Our pick: Kuzyn Builds
We'll be upfront — we're Kuzyn Builds. Here's the factual case for why London homeowners shortlist us, so you can weigh it against the others:
- Published fixed starting prices — The Paul from $148K (no "request a quote to find out").
- Tarion warranty coverage on detached models.
- Named, pre-designed models (The Paul, The Maria, The Henry) you can compare before you commit.
- Family-owned and London-based, hands-on from design and permits through construction.
- 2024 London Urban Design Awards nomination.
Other ADU builders serving London & area
Listed for your research, alphabetically by relevance to the London market — not ranked by quality. Details are from each company's public website; verify before deciding.
Copp Backyard Homes (CBYH)
London areaA division of Copp's Buildall. States it is Tarion-registered and offers several detached models (publicly listed around 395–800 sq ft). Markets available City of London grant support.
Visit Copp Backyard Homes (CBYH) →Opal Building Co.
London areaLondon-based design-build company that lists ADUs and tiny homes among its services.
Visit Opal Building Co. →SWO General Contracting
London areaLondon-area contractor that lists modular construction; publicly references CSA A277 certification for modular builds.
Visit SWO General Contracting →My Own Cottage
London areaPrefab / modular cottage and suite builder; advertises factory-built timelines.
Visit My Own Cottage →Suite Builders
London areaProvincial builder with a dedicated page for London ARUs and secondary suites.
Visit Suite Builders →Frequently asked questions
How do I choose an ADU builder in London, Ontario?
Compare builders on five things: transparent pricing, experience with London’s permit and zoning process, warranty coverage (such as Tarion on detached units), whether they build custom or from pre-designed models, and realistic timelines. Ask to see completed local projects and get the full scope in writing.
How much does it cost to build an ADU in London, Ontario?
In 2026, detached ADUs typically run from about $150,000 to $350,000+ once permits, site servicing and finishes are included, with conversions usually lower. Utility hookups are the biggest source of variation between lots, so a property assessment is the only way to get an accurate number.
Should I choose a modular/prefab or a site-built ADU?
Modular/prefab can shorten on-site time and offer predictable factory quality, while site-built (custom or pre-designed) offers more flexibility for tricky lots and finishes. The right choice depends on your lot access, budget and how much customization you want.
Do ADU builders provide a warranty?
Detached new dwelling units in Ontario can fall under Tarion new-home warranty coverage. Confirm in writing what warranty a builder provides before signing, and whether it applies to your specific ADU configuration.