Do You Need To Hire Consultants If Your Multiplex Has An Architect?

Daniel Clarke
Sep 4
6 min read

Dissatisfaction With The Ordinary

Not hiring engineers as part of your project's design team can lead to a building that you don't want. I will explain why you may want to hire engineers and perhaps also specialty consultants when designing a multiplex, especially a high-performance home.

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To avoid additional consultant fees, most owners who have hired an architect choose not to hire engineers. In BC, the building code allows houses up to 600 m² (about 6,458 sq. ft.) to be designed under Part 9 without an engineer, provided the structure remains within prescriptive limits. More complex designs or local bylaws may still trigger the need for engineering input. Many (most?) potential multiplexes fall into the Part 9 category, so you must determine whether or not the additional value of hiring the engineers is worth the additional fees.

The Benefits Of Professional Expertise

Agnostic To Systems

The subtrades I’ve worked with usually have a preferred set of systems or products, and for good reason. Familiarity makes their work faster, cleaner, and more reliable. Whether it’s a cladding system, a heating unit, the ventilation equipment or the ducting system type, or a combination of insulation and membranes, knowing the material inside out means it goes in smoothly and with fewer errors. Crews repeat the same installation method from project to project, which keeps quality consistent and reduces the likelihood of costly rework.

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Predictability in pricing and supply is another factor. A subcontractor who buys the same products regularly can quote quickly and accurately, drawing on established supplier relationships. They also know the lead times, so orders arrive when needed and avoid holding up construction. That efficiency is a real strength – it makes projects easier to price, schedule, and deliver without surprises.

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The trade-off with this strategy is that it limits your design's ability to meet targets for an ultra high-performance home. Climate-resilient design requires the use of relatively new products and systems. Both an Ultrahome and an Invisible Multiplex incorporate certain insulation material, membranes, exterior finishes, and ventilation systems that were not common a decade ago. A builder trying to build using 20-year-old concepts can only build a house such as many that were built 20 years ago... and are now beginning to deteriorate.

Structural Overdesign

The BC Building Code gives basically two options for designing the structure of a building: engineered (Part 4) or according to the prescriptive requirements listed in the code (Part 9). Part 9 of the building code is written to give builders and homeowners a safe way forward without hiring an engineer. Its rules are intentionally cautious, using simplified formulas and generous safety margins instead of detailed calculations. That caution shows up in familiar ways: the code assumes heavier loads, limits how far floors and roofs can span, requires sturdier bracing, and restricts wall heights and openings to sizes that can be trusted everywhere in the province.

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This buffer is deliberate. It creates a consistent standard across BC and ensures that anything outside these limits is referred to an engineer under the Professional Governance Act. The trade-off is cost: prescriptive designs are often heavier, use more material, and allow less flexibility than an engineered solution. Hiring an engineer can reduce waste and open up options, while sticking to Part 9 alone tends to build in expense along with the conservatism.

HVAC Innovative Strategies

Most HVAC trades have a preferred collection of systems they know inside and out. They understand how the pieces fit together, how to install them efficiently, and how to calibrate the equipment so it runs correctly. Their focus is execution, and in that role they do it well. The limitation is that familiarity tends to narrow the field: systems are often proposed because they are known, not necessarily because they are the only or best option for the project.

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Engineers come at the question differently. While some also lean on familiar system types, a mechanical engineer is trained to evaluate alternatives in light of the project’s specific conditions – climate, building envelope, Step Code targets, energy efficiency, budget, and long-term use. That broader analysis makes it more likely that less common but better-suited systems are explored. The added fee covers this wider perspective: a system chosen for its fit with the building rather than the installer’s toolkit, delivering efficiency, compliance, and reliability designed for the long term.

Landscape Architects

The cost to hire a BCSLA-registered landscape architect avoids complexity and expense down the road. They are trained, licensed professionals working under strict standards of education, ethics, and public accountability – the same discipline and accountability that underpins high-performance building design. Certain municipalities such as West or North Vancouver, Vancouver, and Burnaby have high standards for landscape technical details. Landscape architects do far more than pick plants: they master grading, drainage, infrastructure, and ecological systems, weaving them into a unified, buildable plan and overseeing its execution to ensure what’s drawn on paper actually comes to life. That early coordination builds in climate resilience, water efficiency, and durability from the start, which means fewer surprises and fewer costly missteps.

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A landscape architect anticipates erosion, irrigation, regulation, and maintenance, dealing with them up front instead of after they’ve become problems. The result is a project with fewer overruns, fewer corrections, and a landscape that continues to perform decades later. Most landscape contractors focus on executing existing plans, while landscape architects are trained to develop those plans holistically from the outset.

Solutions Before Shovels In The Ground

A fifth reason to bring professionals onto the team is integration. Their work overlaps – structure with mechanical runs, grading with drainage, and system choices with the building envelope. Engineers and consultants coordinate these intersections ahead of construction, so conflicts are solved in design rather than discovered on site. That foresight reduces surprises, prevents costly revisions, and ensures the building operates as a unified whole. Very high-performance projects such as Net Zero or Passive House certified buildings tend to be successful only when design consultants from all involved disciplines are involved at the beginning.

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By contrast, construction crews are generally going in blind and will try to make things work together as they go. When subtrades are left to resolve overlaps during construction, the outcome is not always but usually a conspicuous workaround that diminishes the building’s design – whether in aesthetics, function, or both. Trades are skilled at adapting in the moment, but those adjustments rarely deliver the same coherence or refinement. Paying for professional coordination secures a design that holds together in execution, where every system is planned to complement the others, and the finished building reflects intent rather than compromise.

These solutions hinge on strong communication between teams during the design process. I've worked with many consultants on different types of projects, so I know how to speak the language of other disciplines. I proactively make allowances or initiate concepts as starting points for the engineers' designs. Seeing their own needs taken more seriously, the engineers usually pay closer attention to the impact of their systems on the design of the building and think more creatively to develop their technical solutions.

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My documentation adds and incorporates in detail the elements from the engineers - structure, piping, ducting, and electrical - in a three dimensional model. Unlike the designers of most small projects, I build my three-dimensional model as a dry run of construction, ensuring systems and details are fully coordinated before anyone is on site.. When it's complete, you, the builder, the subtrades, and I can see how all the pieces of the building fit together.

The construction process is a steady progress without hiccups or panicked changes to design. The house or multiplex goes together exactly as it was drawn, and it finishes on time as planned because the crews already knew what to do. The exterior and the interior look exactly like the renderings; the spaces feel just as you expected. There are no surprises in the finished building - just a feeling of success.

What happens on most job sites though is a struggle from start to finish. The builder or general contractor figures out the best he can how his team and the subtrades will put together their work, but even a "simple house" can have many unique construction details that need to be worked out as they're assembled if they weren't resolved by the designer in 3D in detail ahead of time.

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To ensure that you're not just throwing away money by hiring these additional professionals, you'll need a coordination process that ensures all the required pieces of the engineers' designs is decided and incorporated. My SAPPHR Strategy™ includes that process, but you first need to know which consultants you'll need. My Premium RAD Study™ is a standard, fixed-price predesign study that explores and summarizes your defining characteristics, sets your desired performance targets, and extracts from relevant regulations (bylaws, bulletins, policies, statutes, and codes) that dictate what you can and cannot build. Using this information, it determines what the architectural fee will be for the whole project and which consultants you should retain.

To learn more about how a RAD Study™ would apply to your multiplex project or new single-family home, click on the link below to book a free, 30-minute consultation - the Diagnostic Session.

Book DIAGNOSTIC SESSION

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.