The CMHC Housing Design Catalogue offers free, professionally developed plan sets for small multi-unit housing — ADUs, fourplexes, stacked townhouses, and a sixplex — intended to cut design time and cost for infill projects. The obvious question from every investor and homeowner who finds it: can you actually build from these plans, and what does it really cost?
We work with the catalogue in our own infill development projects, so here are the answers from the builder’s side.
Yes, You Can Build From It — With One Step People Miss
The catalogue’s technical design packages are genuine, buildable drawings — not just concept sketches. But they are prototypical: they were not drawn for your lot, your soils, or your municipality’s zoning overlays. Before a building permit application, the drawings need to be reviewed, adapted to your site, and taken on by a qualified designer — in Ontario, that means a BCIN-registered designer or an architect who reviews and stamps the design for your specific project. Site-specific work like the foundation design, grading, servicing connections, and any zoning-driven adjustments still has to be done. The catalogue saves a large share of design effort; it does not eliminate the design professional.
What CMHC Says It Costs in Ontario
In 2025, CMHC published Class B construction cost estimates (prepared by Vermeulens) for each Ontario catalogue design. The published ranges for hard construction costs:
Accessory Dwelling Unit 01 (634 sq ft, 1-bed): $251,000 to $314,000. Accessory Dwelling Unit 02 (1,017 sq ft, 3-bed): $343,000 to $429,000. Fourplex 01 (3,897 sq ft, four units): $1,174,000 to $1,468,000 — roughly $294,000 to $367,000 per unit. Fourplex 02 (3,264 sq ft): $1,108,000 to $1,385,000. Sixplex (4,842 sq ft): $1,510,000 to $1,888,000, or about $252,000 to $315,000 per door. Stacked townhouses land between $296 and $379 per square foot.
Those numbers are useful for first-pass feasibility — and dangerously incomplete for a budget.
What the CMHC Estimates Leave Out
Read the exclusions list before you build a pro forma on these figures. The estimates exclude HST, land, development charges, building permit and municipal fees, demolition and site development, site servicing (water, sewer, electrical, gas connections), landscaping, contingencies, financing costs, and the owner’s soft costs. They’re based on Q1-2025 Toronto pricing, so they need escalation and a regional adjustment. On an infill multiplex, the excluded items routinely add six figures to the real all-in number — site servicing alone can be one of the largest line items on a constrained urban lot.
In other words: the catalogue ranges are a credible starting point for hard construction costs at mid-range finishes, with a 15% general contractor overhead and profit already assumed inside them. The distance between that number and your true project cost is exactly the territory where feasibility work earns its keep.
Want the Real Number for a Real Lot?
We’ve completed nine infill development projects of our own and work with the CMHC catalogue in our own developments. Send us the address and the design you’re considering — we’ll give you a straight read on zoning fit, the permit path, and what the all-in number actually looks like in this region.
Start a ConversationWhere the Catalogue Fits Best in Waterloo Region
The City of Kitchener has explicitly endorsed the catalogue: it supports use of all seven Ontario designs and permits up to four dwelling units on many residential lots, subject to zoning regulations like lot width, parking, setbacks, and height. That makes Kitchener one of the most catalogue-friendly municipalities in the province — we cover the rules in detail in our guide to Kitchener’s ADU and fourplex framework. For the broader cost picture across ADU types, see our Garden Suite & ADU Cost Guide, and if you’re evaluating this as an investment, our developers and investors page explains how we underwrite these projects.
Frequently Asked Questions
Yes. The technical design packages are free to download and use. The costs that remain are adapting the design to your site, the required review and stamping by a BCIN-registered designer or architect in Ontario, site-specific engineering, permits, and construction itself.
Yes. The drawings are prototypical and must be reviewed, adapted to the specific lot, and taken on by a qualified designer — a BCIN-registered designer or an architect — before a building permit application. Foundation design, grading, and servicing are always site-specific.
CMHC's published Class B estimates put Fourplex 01 at roughly $1.17 to $1.47 million in hard construction costs and Fourplex 02 at $1.11 to $1.39 million, based on Q1-2025 Toronto pricing at mid-range finishes. Those figures exclude HST, land, development charges, permits, site servicing, demolition, landscaping, and contingencies — the all-in number is meaningfully higher.
Yes. Kitchener supports the use of all seven Ontario-region catalogue designs — both ADUs, both stacked townhouses, both fourplexes, and the sixplex — and its zoning permits up to four dwelling units on many residential lots, subject to regulations such as lot width, parking, setbacks, and height.