Eastern Ontario Residential Design
The 3 Most Expensive Mistakes
Homeowners Make Before Designing a Home or Renovation
Why most residential projects go wrong before design even begins
If you are in the early stages of planning a home renovation or new build, there's a good chance you've already started comparing prices for materials, design services, or contractors.
That instinct isn't wrong, but it can lead you straight into the most expensive mistakes residential projects produce. Not during construction. Before the drawings are started.
This article is written for homeowners who are:
- Comparing design service fees and wondering whether the cheaper option is "basically the same"
- Thinking that drawings are drawings, that any competent person can produce what's needed
- Trying to control project costs by starting with a target budget
- Unsure where to start and looking for clarity on what actually matters
If any of those describe where you are right now, the next three sections are worth reading slowly.
Time and time again, homeowners learn the hard way that the most costly mistakes aren't made during construction; they're made in the weeks and months before a single drawing is started. The most costly mistakes are a result of early decisions made, before the drawings are started, and then shoe-horning solutions into place during the construction of the project.
In this article, three of the most consequential mistake categories are examined, along with their real-world impact and what to do instead. The good news is that these types of mistakes are predictable and avoidable.
Why Comparing Design Fees Misses the Point
Most homeowners compare design services on price per drawing set, or on how quickly they can get permit-ready documents. That comparison treats design like a commodity, much like comparing two bags of the same flour at the grocery store.
But design services are not a commodity. The fee you pay up front is not the cost of the service. The cost is everything that follows from the decisions made (or not made) during the design phase.
A low-cost drawing service delivers pages. A thorough design process delivers decisions, tested, coordinated, and locked in before the contractor starts the clock. The difference between those two outcomes is often measured in the tens of thousands of dollars spent once construction begins.
For a deeper look at this distinction, see: Value Versus Price — The Difference Explained →
Mistake #1: Designing Before Understanding the Building Site's Constraints
Impact: Major — Project Show Stopper
I've marvelled at how homeowners, new or experienced, start with visions of a beautiful home, selecting a design from a plan book or using images from Pinterest as the foundation for their dream house. Then the long journey to find a lot to accommodate this vision begins, often ending in frustration or significant compromise.
Low-cost drafting services reinforce this approach by offering an unrealistically low price point and fast "permit-ready drawings" services that homeowners quickly learn exclude any professional oversight or guidance. These services just take your money and run, leaving you to deal with a project riddled with risk and soon-to-be-realized costly errors.
It happens so often that general contractors treat plans as a "suggestion" rather than the contractual documentation they are truly meant to represent between you, the municipality, and the contractor.
I know this first-hand because I've had to build from drawings like those I've described. The exercise is nothing short of being a constant source of frustration, anxiety, and emotional turmoil for all parties involved.
Here's how you avoid becoming a victim of Mistake #1: develop a thorough understanding of the project before you even consider drawing a single line, selecting a plan, or cutting down any trees. Unexpected issues such as drainage problems, road allowances, waterfront setbacks, mature tree preservation, and floodplain restrictions can render initial building plans completely unworkable, leading to the abandonment of final designs after significant emotional and monetary investment.
Key Site Factors That Must Be Understood Before You Hire Anyone
Ask yourself this question before moving forward:
Do I have answers to all of the items above? If the answer is No to even one of them, stop now, and get those answers before hiring anyone.
A lack of understanding of any of these key items puts your project at real risk of unanticipated costs. Simple avoidable missteps lead to inefficient construction solutions, higher utility bills, and long-term mistakes that limit the property's enjoyment.
Contractors are not responsible for your lack of due diligence, but they do profit from it. Studying the site early is inexpensive, necessary, and a sound investment.
Skipping early site analysis locks in expensive, long-term problems. Start with the site, and you lay the foundation for a home that works with, rather than against, its environment.
Real-world impact
In one Eastern Ontario new build, a floodplain setback from a drainage ditch was discovered after the building permit drawings were reviewed by the Conservation Authority. Upon learning that the Conservation Authority rejected the plans, the municipality also rejected the application. The problem was that, to get a jump on the project, the contractor had advised the client to purchase the floor and roof trusses as soon as possible, which they did with cash. Learning that the plans were of no value and the project had to be abandoned as designed, the owner had no recourse but to scrap the purchased floor and roof trusses and restart the design process. The cost: $60K for materials, plus $24K for rent to cover the 1-year delay.
In TLOL's process, this is what we call Gap 1, the point where unconfirmed site constraints put every downstream decision at risk. Closing Gap 1 is the first step in the Design Feasibility & Risk Review.
Mistake #2: Treating Drawings as a Commodity
Impact: Severe — Recoverable but Heavily Cost-Prohibitive
A costly mistake is treating drawings as just another administrative task, something to produce quickly so you can get the permit and start building. This thinking ignores the vital role that design plays in achieving a livable, functional home.
Too often, homeowners undermine their projects with one belief: "We just need drawings for the permit." This mindset bypasses the valuable concept and schematic phases, which exist to explore solutions, assess feasibility, and ensure the design actually serves the homeowner's life, not just the permit office's checklist.
Let me give you a specific example of what this looks like in practice.
I once reviewed a design the husband had selected from a plan book and said it satisfied the family's needs. However, I pointed out that they would have to carry dirty laundry from the bedrooms and bathrooms, through the kitchen and eating areas, past the front door, then across the living room to the utility area located behind the garage. Groceries followed a similar route: from the car, through the garage, across the living and dining areas, past the front door, and then into the kitchen. The front entrance looked impressive from the exterior, but also lacked a closet for guests' coats or shoes. Coats would have to be piled somewhere, along with the shoes, most likely on the floor of the front entrance.
The garage was placed on the sunny southwest end of the lot. The large living windows faced north, and the kitchen patio doors were placed so you would have to walk around the table and chairs in the eating area. The street could only be seen from the interior of the house by opening the front door and stepping outside onto the porch. Plus, the foundation and site plan were not included in the plan set, and customization/changes were an extra charge.
When this situation was pointed out to both the husband and wife, the wife rejected purchasing the pre-drawn package as unworkable. The husband thought the plans worked well because the utility sink was close to the garage for clean-up, and he could leave his soiled clothes in the washing machine at the end of the day. Upon closer examination, the design failed to support the family's practical living activities and site orientation. As a result, the design was abandoned, and an agreement was made to start the design process with a Design Brief first.
Before the concept design phase begins, all stakeholders must be involved in making decisions. Initial ideas are tested against the client's lifestyle requirements set out in the Design Brief and compared for fit, one kitchen layout versus another, one circulation path versus another. In the schematic phase, those ideas are refined into detailed floor plans and a digital twin, with visualizations that show how the spaces serve the homeowners' actual needs. These are not extra steps. They are the steps that determine whether what gets built is worth building.
Well-crafted design is built upon:
- Input from all stakeholders
- Understanding the problems you are trying to solve
- Exploring options and selecting the best fit
- Testing solutions to ensure they suit your lifestyle
- Protecting your investment through informed, early decisions
Homeowners should focus on defining the problem the design solves by completing a Design Brief first. This allows all stakeholders to express their needs, enabling the design to explore and test solutions against the requirements. Strategic decisions made early in the design process protect investment and result in a home that is functional and satisfying for the long term.
Real-world impact
A homeowner who buys plans based solely on price and goes straight to permit drawings without using a digital twin to test constructability receives bids with a higher markup than bids for the same project that uses a digital twin to test the constructability. Why? Because the project has been pre-built, tested, and verified, the risk for something the contractor has to "eat" is removed.
This is Gap 2 in practice, design decisions that were never tested, never locked, and carried forward into construction as assumptions. The Concept Design phase exists specifically to close this gap before drawings are finalized.
Mistake #3: Making the Contractor Solve Design Problems
Impact: Very High — Costly Tear-Outs, Rework, and Delays
I walked onto one project where a structural beam was needed as a result of a change implemented by a floor truss supplier. It happened because the floor truss designer switched the direction of the floor trusses, so they ran perpendicular to the direction shown on the floor plan. Otherwise, the floor trusses would have been overspanned for their size. The framing crew simply packed up their tools and walked away. "Call us when you figure it out because we aren't paid to stand around," was their response. Nobody had assessed the building's constructability prior to ordering the floor trusses. That unresolved decision cost the homeowner a two-month delay, plus the costs to implement the fix. This isn't rare. It's what happens when design problems carry over into construction.
Contractors are skilled at following clear instructions. They are not prepared to:
- Test the plans for inconsistencies
- Analyze how choices will affect long-term performance
- Redesign building components while construction is underway
- Assess moisture and thermal risks as a coordinated system
- Balance structural requirements or mitigate HVAC and plumbing routing collisions
When design questions aren't resolved before construction starts, errors in the plans impact deliverables. Timelines are abandoned because people's primary incentives are schedule and margin, not solving the overlooked problems in the home's design. A contractor who has to choose between keeping his crew on a stalled project or one that's moving will choose the project that keeps the crew moving.
This typically leads to:
- Simpler details that hide constructability issues
- Assembly details affecting energy efficiency and moisture control
- Last-minute material substitutions that affect how the building performs
- Trades interpreting the same gap in the drawings differently
Unresolved design problems also compound. A constructability issue that requires a structural engineer to produce a solution stalls and then kills any momentum a project may have had. The homeowner pays for all of them.
A thorough design creation and testing process gives contractors clear building instructions, specific performance targets, and fewer unexpected issues, which means fewer change orders, fewer delays, and a build that proceeds the way it was intended.
Design should not be left to resolve during construction. When contractors solve design problems, homeowners pay more, immediately, and for years afterward through compromised performance, comfort, and durability.
Real-world impact
In a new home project, the lack of a constructability review resulted in $22,000 in unplanned change orders, none of which were covered in the original budget. The original difference in the design fee that would have resolved all three was an extra $3,800.
When coordination isn't owned by the design professional, it defaults to whoever is on site. This is Gap 3, and its cost doesn't appear on one line item. It accumulates across every trade, every substitution, and every last-minute fix. The digital twin Construction-Ready Drawings process is designed to close this gap before the first shovel goes in the ground.
What These Three Mistakes Have in Common
The same pattern runs through all three: decisions get made before the information needed to make them well is actually in place. The site isn't understood before the design starts. Design decisions aren't tested before drawings are issued. Coordination isn't owned before construction begins.
Each mistake opens a gap. And each gap left open becomes a cost during construction, or over the lifetime of the home.
That pattern is what TLOL's process is built to interrupt, at each of those three points, before the cost is locked in. You can see exactly how that works here: Our Workflow →
Recognized your project in any of these scenarios?
The next step is a conversation, not a sales call. The Project Clarity Call is a 30-minute diagnostic to establish where your project actually stands and which of these three gaps is most open right now.
If you'd prefer to start on your own, the Certainty & Risk Reality Check quiz takes less than five minutes and gives you a clear read on your project's current risk profile.
Both are free. Neither requires a commitment to anything further.