Duxton triple-pane windows
More comfort in less space.High-performance triple-pane windows help reduce heat loss, drafts and cold interior surfaces — especially important in a compact ADU where every room is close to the exterior envelope.
Accessory Dwelling Units • Net Zero Ready
Prefab ADUs Built for More
More family. More space. More possibility.
Add a high-performance accessory dwelling unit to your property for family, rental income or flexible living. Explore pre-designed prefab ADUs built with PHI-certified components and Passive House building principles for lasting comfort and energy efficiency.
Designed for Canadian climates. Available across Ontario and beyond.
Your lot + one more home
Pick Your ADU Building Option
Two Ways to Build Your Quantum ADU
Whether you're working with your own contractor or want Quantum to manage the full build, both options use the same high-performance prefab ADU building system. The difference is how much of the construction process you want Quantum to handle.
01 Envelope
Essentials Package
Your high-performance ADU building envelope.
Quantum manufactures, delivers and installs the core ADU structure and building envelope, allowing you or your contractor to complete the remaining site work, services and interior construction.
Quantum Provides
- PHI-certified panels — delivered and installed
- Foundation and slab
- High-performance / ENERGY STAR windows and doors
- Complete high-performance thermal envelope
- High-performance roof system
- Blower-door test and airtightness sign-off
- Comprehensive completion report
- Wall-care guide for your trades
02 Finished
Complete Turnkey ADU
Your finished high-performance accessory dwelling unit.
Quantum manages the ADU project from planning through final handover, coordinating the construction of the finished unit so you don't have to manage multiple trades yourself.
Quantum Provides
- PHI-certified panels and complete building envelope
- Foundation and slab
- High-performance / ENERGY STAR windows and doors
- Mechanical systems, HVAC, electrical and plumbing
- Interior finishes — drywall, flooring, painting and trim
- Cabinetry, countertops and fixtures
- Trade coordination and construction management
- Final walkthrough and handover
Important ADU Project Considerations
Package pricing does not include delivery, geotechnical assessments, site surveys, excavation, driveway or access modifications, landscaping, demolition or tree removal if required, or sewer, water and electrical service connections.
For ADU projects, additional costs may also apply where the existing property requires service upgrades, trenching, utility modifications, grading, drainage work or other site-specific improvements.
Municipal approvals, zoning requirements, development charges and permit-related costs may vary by location and are confirmed as part of the project planning process.
Final inclusions, exclusions and site-specific requirements are confirmed in your project quotation.
Find Your ADU
6 Prefab ADU Models.
One Building System.
6 high-performance designs for family, rental income and flexible living
Explore our collection of pre-designed prefab ADU homes, from compact studios to larger backyard suites. Compare layouts, sizes and build options to find the model that best fits your property, budget and goals.
Find the right size, layout and building package for your property.
Studio
A compact, high-performance space built for maximum efficiency — ideal for rental income or minimal living.
Essentials $105K
Turnkey $272K
View the Studio ADU
Cove
A simple, efficient one-bedroom home — perfect for small lots, rental income, or independent living.
Essentials $120K
Turnkey $298K
Browse the Cove ADU
Accessible BirdNest
A fully accessible home designed for comfort, independence, and long-term living — without compromise.
Essentials $157K
Turnkey $354K
Explore the BirdNest ADU
Kin
Our most versatile layout — ideal for families, multigenerational living, or maximizing long-term value.
Essentials $164K
Turnkey $366K
Explore the Kin ADU
Grange
A balanced two-bedroom layout with indoor-outdoor connection — ideal for everyday living or hosting.
Essentials $166K
Turnkey $380K
See the Grange ADU
Loft
A complete home with extra room to grow — designed for full-time living, families, or long-term flexibility.
Essentials $180K
Turnkey $427K
View the Loft ADU
Included as standard
What's included in a Quantum prefab ADU?
High-performance features that make small-space living better.
In-floor heated bathroom tile
Warm floors. Small detail. Big difference.Electric in-floor heating beneath the bathroom tile adds comfort where you feel it most, making the space warmer and more inviting through cold-weather mornings.
All-electric living
Simple systems. One energy source.Quantum ADUs are designed around efficient electric systems for heating, cooling and hot water — helping simplify operation while supporting high-performance and Net Zero Ready design goals.
ERV — energy recovery ventilator
Fresh air without throwing away the heat.Continuous balanced ventilation brings filtered outdoor air into the ADU while recovering energy from outgoing air, helping maintain fresh air and comfortable indoor temperatures year-round.
Ductless mini-split HVAC
Efficient heating and cooling for compact living.A properly sized ductless mini-split provides efficient heating and cooling without a conventional furnace or extensive ductwork — a simple solution well suited to smaller ADU floor plans.
PHI-certified high-performance panels
The performance starts in the walls.Quantum ADUs use prefabricated wall components designed for high-performance building envelopes, with deep insulation, airtightness detailing and cold-climate performance built into the assembly.
Quantum QTL — standard finishes
The finishes are chosen too. And every one of them can change.
Every ADU ships with the Quantum QTL finishes package — flooring, cabinetry, counters, tile, fixtures and hardware, already specified so nothing stalls while a decision gets made.
Any of it can be swapped. Replace a finish, a fixture or the whole palette through a change order and the build carries on.
Not sure which ADU fits your property?
Explore My Options Why the building envelope matters
Why high-performance prefab wall panels perform differently
Every Quantum home begins with a high-performance building envelope made from precision-manufactured prefab wall panels.
Compared with conventional code-minimum wall assemblies, our panelized system is designed to deliver deeper insulation, better airtightness, more consistent construction quality and improved cold-climate performance.
Conventional wall Quantum panel Drag to compare Traditional wall construction
Conventional site-built wall assemblies can meet code requirements, but performance depends heavily on detailing, workmanship and site conditions.
- Higher Energy Bills More heat loss in winter and heat gain in summer.
- Less Comfortable Drafts, temperature swings, and cold spots.
- Lower Indoor Air Quality Air leakage allows dust, allergens, and moisture to enter.
- Longer Build Times Weather delays can slow construction.
- More Maintenance Greater risk of moisture damage, mold, and premature wear.
- Lower Long-Term Value Performance may not meet the expectations of future buyers.
- More Noise Transfer Thinner assemblies allow more outdoor noise to enter.
High-performance prefab wall panels
Quantum's prefabricated wall panels are manufactured in a controlled environment and engineered as part of a complete high-performance building envelope.
- Ultra-Low Energy Use Up to 80–90% lower heating and cooling demand.
- Exceptional Comfort Consistent indoor temperatures with virtually no drafts or cold spots.
- Healthier Indoor Air Filtered fresh-air ventilation and airtight construction.
- Faster, More Predictable Builds Factory-built panels reduce delays and improve quality control.
- Built to Last 100+ Years Durable wall assemblies designed for long-term performance.
- Higher Property Value Growing demand for energy-efficient, high-performance homes.
- Peace & Quiet Built In Advanced insulation helps reduce outside noise.
PHI-certified components Quantum uses Passive House Institute certified wall components, engineered for high-performance building envelopes in cool and cold climates.
Precision-built prefab envelope Our wall panels are factory manufactured for consistent dimensions, insulation placement and air-control detailing before arriving on site.
Net Zero Ready by design A highly insulated, airtight building envelope can significantly reduce heating and cooling demand, making it easier to design toward net zero performance.
Built with less waste. Designed to use less energy.
Factory prefabrication helps reduce on-site cutting and material waste, while a high-performance building envelope helps lower the energy required to heat and cool the home.
You already know you want the space. The question is how well you want it built.
An ADU is a long-term investment in your property. The building envelope, windows, ventilation and mechanical systems you choose now will determine how comfortable, efficient and durable that space feels for years to come.
Small buildings can be especially sensitive to poor detailing because every square foot is close to an exterior wall, window or roof.
A conventional code-minimum ADU may still mean:
- More heat loss through the building envelope
- Greater potential for drafts and temperature swings
- Less consistent indoor air quality
- More reliance on heating and cooling equipment
- More site-built variability and weather exposure
- Higher operating costs over time
The Build It Better Point of View
If you're going to build it, build it for the long term.
Quantum prefab ADUs are designed around a high-performance building envelope rather than minimum compliance.
Our panelized construction, high-performance windows, airtightness strategy and balanced ventilation work together to create a space designed for year-round comfort, lower energy demand and lasting performance.
Small home. Full-size building performance.
From Quantum homeowners
What homeowners say about living in a Passive House home
Discover why homeowners choose Passive House construction for greater comfort, healthier indoor air, lower energy costs, and long-term durability.
“Good for us and good for the earth.”
We chose Quantum Passivhaus because integrity is important to us. We weren't just building a house, we were building a way of life, and a connection with the earth.
We've lived in the house over 7 years now and still appreciate the comfort it offers — consistent temperatures from room to room, clean, fresh air, and no cold floors or drafts. During an ice storm, we went 11 days without power and barely lost any heat. The house just works, and our energy costs are much lower than what we were used to.
We feel very fortunate to have this beautiful home. It's good for us, good for the earth, and good for our pocketbook. We highly recommend this company.
Marci Mandel & Alan Clark Quantum homeowners since 2018
“The biggest difference living here is comfort.”
Our energy costs are dramatically lower than before, but more than that, the house just feels good. Everyone who stays here says they sleep incredibly well.
Gail & Mike Holness Quantum homeowners
“It feels like a cocoon for our family.”
The house is incredibly quiet, consistent from room to room, and the air feels clean. There's very little dust, and the comfort is something you notice every day.
Kathy & John Sprowl Quantum homeowners
“I don't understand why everyone doesn't build to this standard.”
From a cost perspective, it was basically the same as building a traditional house at the time, but the efficiency is far better. Everything here is electric, and we only have one bill.
Gerry & Hilde Moraal Quantum homeowners
Before you book a call
ADU questions, answered straight
The things people actually ask us — including the awkward ones about price, scope and what happens when something goes wrong.
What's the difference between the two packages?
Essentials gives you the complete building envelope installed, all mechanical rough-ins done, and the structure brought to finished drywall with all inspections passed. You handle paint, flooring, fixtures and final trim. Complete Turnkey means Quantum acts as your General Contractor from foundation to final walkthrough — every trade, every permit, everything coordinated. Both packages are built on the same PHI-certified panels and the same high-performance envelope. The difference is how much of the project you want Quantum to own.
Are these Passive House certified buildings?
The exact language matters. These ADUs are built with Passive House Institute-certified cold-climate panels. The panels themselves carry the certification. We do not describe the buildings as Passive House certified unless that specific building certification has been achieved.
What does Net Zero Ready mean?
Net Zero Ready means the building is designed and built to perform at a level where it could achieve net zero energy consumption — it just hasn't been formally certified yet. The envelope, airtightness, insulation and mechanical systems are all specified to that standard.
On Complete Turnkey builds, Quantum works with Homesol, a third-party energy modelling partner, to verify performance. The Net Zero Ready label itself is a builder-driven certification and applies to Turnkey builds only. Essentials packages are engineered to the same performance standard — the label requires a certification process that only applies when Quantum is the builder of record end to end.
Is the price fixed?
For Complete Turnkey, the scope is presented as a fixed-price contract for Quantum's standard scope. For Essentials, the panels, envelope, rough-ins and drywall are fixed — everything you coordinate beyond that is subject to your own trade quotes. Site preparation, foundation engineering, service hookups and geotechnical work are outside both package scopes and discussed as allowances before you sign anything.
What does the 30-day delivery guarantee mean?
On the Essentials package, Quantum guarantees the superstructure will be up within 30 days — from permit approval if a permit is required, or from signing if not. The 30-day guarantee applies to the superstructure only. Complete Turnkey timelines are agreed upon during the sales process and subject to permit approval where required.
Is Quantum the General Contractor?
On Complete Turnkey, yes — Quantum acts as your General Contractor from first conversation to final walkthrough. On Essentials, you coordinate your own trades for paint, flooring, fixtures and final trim. If you want Quantum's process without the full Turnkey price, the PM Package and PM Service add-ons are available on Essentials.
What is the PM Package and PM Service?
Both are optional add-ons available on the Essentials package. The PM Package ($5,000) gives you Quantum's material takeoff, QC checklist, project timeline template and permit process overview — everything you need to manage your own finishing trades professionally. The PM Service ($15,000) means Quantum finds and manages qualified local trades on your behalf. Essentials price. Turnkey experience.
Can I build one on my property?
Many Ontario residential properties can now support multiple units as-of-right under current legislation. Suitability still depends on your specific site, servicing and local conditions. That's exactly what the first call is for — we'll tell you quickly whether it's a realistic fit.
What's included, and what isn't?
Included on both packages: PHI-certified panels, Duxton triple-pane windows, ERV, heat pump, in-floor bathroom heat, electric hot water, siding and roofing. Complete Turnkey also includes drywall, flooring, paint, trim, cabinetry, countertops and fixtures. Essentials includes drywall and all rough-ins — paint, flooring, fixtures and final trim are yours to complete. Appliances are not included in either package and are available as an add-on.
Excluded from all packages: site preparation, foundation engineering, service hookups and geotechnical work. We walk you through exclusions before you sign — not after.
Won't a sealed house have poor air quality?
This is the most common concern — and the one the building completely disproves. The ERV continuously exchanges fresh outdoor air, recovering heat before it escapes. The result is cleaner air than a vented standard home.
"I used to have a really dry nose. I don't anymore." "Everyone who stays here gets a good night's sleep." The mechanism works all the time, automatically.
Do I need a feasibility study?
For a pre-designed ADU, a full custom feasibility study isn't required. After your 15-minute call, if you're ready to move forward, a $500 commitment deposit holds your spot. If you proceed to contract, that $500 rolls in. If you don't proceed, you keep the feasibility document. It's designed to filter serious buyers and protect everyone's time.
What if something goes wrong during the build?
Things go wrong on every build. All four homeowners we interviewed mentioned something that didn't go as planned. All four still recommend Quantum without hesitation.
What they said, unprompted: "Things went wrong, but they always had our backs." No nickel-and-diming. No "that's not our problem." We fix it.
It costs more. Is it worth it?
Yes — if you're comparing the right numbers. A code-minimum ADU is cheaper to build and more expensive to own. Higher energy bills every year. Tenants who leave in January because heating costs too much. Nobody who owns a Quantum ADU asks whether it was worth it after their first winter.