Why Are Multiplexes So Expensive To Build?
- Daniel Clarke
- Jun 28
- 6 min read
Get More, For Less
Most single-family property owners who look into the cost of building a multiplex get deflated not long after starting their research, but I'll explain why the construction costs are high and why they're avoidable.
Many people who own single-family homes have been hearing since mid-2023 about the promise of being able to build Small-Scale Multi-Unit Homes (SSMUHs) / Multiplexes / houseplexes, but are disheartened when they discover that the construction cost knocks them out of the game. They give up before realizing the new zoning’s potential.
But here’s the truth: the promised opportunity—providing housing, earning revenue, securing family future — is possible. It's not about spending more. It's about building smarter.
Business as Usual
Some people understand the value of a high-performance home, especially if they're building a multigenerational home for extended family. But when struggling simply to get a roof over their heads, they often opt for what they *think* is the least expensive route but end up paying more in the long run.
Individuals, families, and development firms all inadvertently make decisions that cause unnecessary expense or prevent a project from moving forward. Let’s review a few core assumptions that often steer people wrong.
The Three Big Mistakes
Even well-intentioned developers fall into common traps that sabotage performance and inflate costs.
Tactic #1: Buy Low Sell High
The principle of “buy low, sell high” is sound in theory, so I won't count it as a mistake. Find a reasonably-priced piece of land, and pull the trigger when you think you can build big enough to sell for way more.
If the land has hidden constraints though, you may not be able to capitalize on the low price. Too often, a developer will have its own feasibility analysis based on market studies and on simple zoning parameters that points to profit, but other factors toss the potential profit out the window. I offer a fixed-price feasibility report called the RED Report™ to determine a site’s true potential before design work begins.
Mistake #1: Rushing Design And Chopping Fees
The most common mistake is moving ahead too quickly with drawings that are rushed or underfunded—usually in an attempt to save time and money. The logic seems sound: start quickly, keep upfront costs low, and get a permit as soon as possible. But when drawings are done too fast or for too little, they’re often incomplete, inaccurate, or uncoordinated.
You inevitably miss crucial regulations—zoning quirks, environmental or physical features, new or special building code requirements, utility constraints—that force changes later. Each oversight means a revision to your design, another application to the city, and more time lost. That’s time spent paying interest on loans, delaying your project’s income, and repeating the same expensive work.
And because the consultant’s scope was limited, key building systems—structure, envelope, mechanical, plumbing—haven’t been coordinated. This leads to conflicts during construction, expensive workarounds, and delays that could have been avoided with better planning up front. In trying to reduce early risk, many projects end up with exactly the kind of budget overruns and time losses they hoped to avoid.
Mistake #2: Self-Managing the Project
The third mistake is trying to manage the design or construction process yourself. Homeowners and even small developers sometimes try to save money by hiring subtrades directly — finding their own painter, plumber, or cabinetmaker. Others opt for construction contracts where they hold all the subtrade agreements, and the general contractor simply “manages” the process.
This can work, but it’s rarely efficient or cost-effective. Without adequate or direct experience in sequencing, supervision, and coordination, the project stalls at every trade interface. Gaps between subtrade scopes create delays, quality control slips, and disputes become common.
A good general contractor, on the other hand, brings more than just scheduling. They have an established roster of preferred subtrades — companies they’ve worked with over multiple projects. This long-standing relationship means the contractor knows the subtrades’ capabilities, quality of workmanship, and responsiveness. That familiarity translates into smoother scheduling, fewer surprises, and greater confidence that the work will be done properly and on time.
Mistake #3: Choosing Cheap Materials
The fourth mistake is choosing the cheapest construction materials—particularly for the hidden parts of the building that are out of sight once construction is complete. This might include thinner sheet metal for flashings, less durable insulation products, coatings that degrade more quickly, or switching to different metals for fasteners and brackets that corrode faster or react poorly with surrounding materials.
Because these substitutions aren't visible in the finished product, they often go unchallenged—until they fail. Moisture intrusion, temperature instability, rusting components, or degraded finishes can all result from these unseen compromises.
Some owners assume that the builder’s warranty will shield them from the effects of these decisions. But most new home warranties—like the 2-5-10 model—only cover the building envelope for five years. Failures may not show up until year six or later, at which point the repair is entirely at the owner's expense.
I’ve spent the last several years immersed in the economics of small-scale housing—working not just as an architect, but as an advocate for smarter, more resilient design. I understand the constraints facing homeowners and small developers, because I work with them every day. I’ve seen what works, and more importantly, I’ve seen what doesn’t. I know how easy it is to waste money chasing false efficiencies—and how rewarding it is when the right approach unlocks a project that would otherwise stall.
With The Right Approach
My design process is built around early coordination, clear priorities, and performance without excess. It begins with a close reading of the site, the zoning, and the specific needs of future occupants. I lead a team of consultants whose expertise is integrated from the outset—not applied retroactively. This approach results in projects that are more predictable to build, easier to price, and more enduring in quality.
When the process is deliberate and well-structured, projects gain clarity early. Drawings are more accurate, systems are better aligned, and builders are able to work more efficiently. The construction phase proceeds with fewer interruptions, and the final building performs well—with consistent comfort, low maintenance, and lasting value. The quality isn’t just seen—it’s felt, quietly and continuously over time.
On the other hand, when key decisions are made too early or without proper coordination, projects tend to accumulate inefficiencies. Consultants may be engaged only after major design choices have already been fixed, resulting in systems that compete for space rather than working in harmony. The construction process becomes reactive, with changes that increase costs and prolong schedules. The completed building may satisfy minimum requirements but fall short in performance, comfort, and long-term value. The opportunity for a more thoughtful, durable outcome is gradually lost.
What Comes Next
There is a better alternative. The Invisible Multiplex is a different model of housing—one that looks modest but performs exceptionally. It offers greater comfort, resilience, and longevity than typical buildings, often at a lower cost. In the next article, I’ll walk through what makes this model possible, and how it can be applied to your next project.
If this building will be your home, your family's home, or your flagship development, long-term reliability matters. Cost-cutting in hidden assemblies often leads to highly visible failures—and expensive remediation—down the road.
Do you own a R1-1 property and want to know what your options are for building a triplex or other multiplex? I offer a simple redevelopment study service called the RED Report™. Download a sample by clicking the link below.
If you'd like to book a free, 30-minute consultation with me to discuss how to move your development plans from the rough idea stage into the solid research phase, click the button below.
DISCLAIMER:
The information included in this article is to an extent generic and intended for educational and informational purposes only; it does not constitute legal or professional advice. Thorough efforts are made to ensure the accuracy of the article, but having read this article, you understand and agree that Daniel Clarke Architect Inc. disclaims any legal liability for actions that may arise from reliance on the information provided in this article. I am an architect in BC, but readers are recommended to consult with their own architect on their specific situations before making any decisions or exercising judgement base on information in the article.
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