At a glance
- Builds do not go over budget for a hundred mysterious reasons. They go over for a small handful of predictable ones, and most are set in motion before construction starts.
- The biggest driver in recent homeowner data is not changed minds. It is estimates that were too low to begin with, trued up later through allowances and change orders.
- Revelstoke stacks real local costs on top: permit fees from $10.25 per $1,000 of project value, development cost charges that can exceed $60,000, Step 3 energy requirements, a snow load roughly four times Vancouver’s, and an avalanche corridor between you and your materials.
- Contingency helps, but it is not the fix. The fix is a complete design and full selections before the price is set, locked into a fixed-price contract that puts overrun risk on the builder.
- Two questions expose most of the risk before you sign: cost-plus or fixed-price, and is the number backed by a real selections package and schedule?
Almost every story you hear about a custom home going sideways is a story about the budget. The design was beautiful, the builder was capable, and yet somewhere between the handshake and the housewarming the number crept up, one line at a time, until the finished cost bore little resemblance to the figure everyone started with. It is the fear that sits underneath every other question a buyer asks, and it is loudest for someone building a vacation home four or five hours away, or a corporate buyer who has to answer to a board for the final total.
Here is the part that gets lost in the anxiety. Builds do not blow up for a hundred mysterious reasons. They blow up for a small handful of predictable ones, and most are set in motion before the first shovel touches the ground. Once you can name them, the fix becomes clear, and it is not luck or a bigger cushion. It is defining everything up front and locking the number into the contract. This post walks through why builds drift, the Revelstoke realities that make it sharper here, and the levers that hold a price in place.
The estimate is not the problem. The drift is.
Most buyers treat the opening estimate as the number that matters, then feel blindsided when the real cost lands somewhere else. The estimate was never the risk. The risk is everything that happens after it, the slow accumulation of decisions, surprises, and small overages that were never priced in the first place.
The best homeowner-level data comes from renovation surveys in the United States rather than BC custom builds, but the mechanism is universal. In the 2026 U.S. Houzz and Home Study, more homeowners went over budget than spent what they had planned, 37 percent against 35 percent for their 2025 projects, and a separate US report from Angi found that more than half hit surprise expenses. Surprises are the base case. A build that lands on its number is one where someone did the work up front to remove them, not one that got lucky.
Where those overruns came from matters. Among the Houzz homeowners who went over, 52 percent pointed to unexpected product or service costs, meaning the estimate was simply too low, not that they changed their minds halfway through. Another 35 percent chose materials more expensive than they had planned, 31 percent expanded scope mid-build, and 22 percent discovered construction problems once work was underway. Almost none of that is random. Every item is a decision or an unknown that could have been settled before the price was fixed.
The predictable reasons builds go over
Strip away the specifics and custom builds drift over budget through the same recurring mechanisms. Understanding them is most of the battle.
The first two are allowances and change orders, and they usually travel together. An allowance is a placeholder, a lump sum written into the contract for something you have not chosen yet, such as flooring, fixtures, or cabinets. Industry guidance describes it plainly as a lump sum in the contract price allocated for items the homeowner selects directly. If the tile or plumbing fixtures you eventually fall for cost more than the guess, you cover the difference, and that difference is processed as a change order, a written amendment to the contract that must be made in writing and agreed to by both parties. A budget built on optimistic allowances is really one that expects a run of change orders, and each is a small renegotiation of your number after you have already committed. Our comparison of fixed-price and cost-plus contracts takes these two mechanisms apart in detail.
The third is scope creep, the more human cousin of the change order. It is the finished basement that was not in the original plan, the upgraded kitchen, the wider deck. Each addition feels small and reasonable in the moment, yet together they are one of the most common reasons a project ends up well past its opening figure, and they stay invisible until you add them up.
The fourth is unforeseen site conditions, the one buyers underestimate most because it is the one they cannot see. What sits below a lot does not care what your budget says. Bid a job expecting to dig through soil, hit solid rock a few feet down, and the excavation stretches well past plan. A water table the test holes missed can force dewatering costs that were in nobody’s budget, and the real damage is often the schedule rather than the direct fix, since a foundation redesign in the field can add weeks or months. On a sloped, rocky mountain lot, none of this is exotic.
The fifth is material price volatility, and this one is current. Statistics Canada reported that residential building construction costs rose 3.7 percent year over year in its 15-city composite in the second quarter of 2025, and were still climbing at 2.8 percent year over year in the first quarter of 2026. More to the point, the agency attributed increased volatility in both the pricing and the availability of certain materials to the tariffs imposed by the United States and the countermeasure tariffs implemented by Canada. A price that was accurate when your estimate was written can move underneath you while the project is in the ground.
The sixth is soft costs, the fees and studies that never show up in a glossy render but land squarely on the invoice. Permits, development cost charges, engineering, and energy modelling are all real money, and left out of the opening figure they arrive later feeling exactly like an overrun, even though they were knowable from the start. The seventh, threaded through the rest, is schedule slippage. A longer project carries more financing cost and meets more of the surprises above, so a budget that ignores the calendar has a hole in it.
The Revelstoke drivers that make it worse
Every one of those mechanisms exists anywhere you build. Building in a mountain resort community stacks a few more on top, and they are large enough that leaving any of them out of the opening number more or less guarantees a gap later.
Start with the fees that are the price of admission. In Revelstoke, the building permit fee starts at $10.25 per $1,000 of project value, so a $1 million build carries at least $10,250 in permit fees before a shovel is in the ground. Development cost charges are larger again. On a single-family home with a secondary suite they can run roughly $60,000 or more under the DCC bylaw that took effect on August 1, 2025, and because those charges are calculated on floor area, the number scales with the size of the home. Neither is a surprise to a builder who works here, which is exactly why they belong in the price from day one rather than in a phone call three months in.
The energy code adds another layer. Revelstoke currently builds to Step 3 of the BC Energy Step Code, and the lower steps typically add under 2 percent to construction cost according to the province’s own metrics research. Higher steps and a Zero Carbon Step Code are on the way, and it is worth being precise that net-zero-ready means a home built to use significantly less energy for heating and cooling, not zero energy. The code you are building to has cost implications, and they should be priced against the actual step, not discovered partway through.
The structure itself costs more here, for a good reason. Revelstoke sees a ground snow load of around 7.2 kilopascals, roughly four times the load a Vancouver home is designed for, rising by about a kilopascal for every hundred metres of elevation. A roof and structure engineered to carry that much snow is not the same building as one designed for the coast, and the engineering that gets you there is a real line in the budget rather than an afterthought.
Finally there is the mountain between you and your materials. Everything coming into Revelstoke travels through Rogers Pass, Glacier National Park, and 3 Valley Gap, all of which are avalanche-prone, so winter delivery delays are part of building here. Layer that onto the timelines a custom build already runs, a design phase of 6 to 9 months, permit processing of 6 to 8 weeks, and construction of 9 to 12 months with larger builds taking longer, and the schedule risk that turns into carrying cost is obvious. A firm number that has already accounted for the mountain is worth more than an optimistic one that has not.
How to lock your number
If the drift comes from a short list of predictable causes, then holding the price steady is a matter of closing each door before construction starts. It begins with a complete design and a full set of selections. Almost every mechanism above traces back to a decision that was deferred, and a deferred decision is an open door for the price to move. When the design is finished and the real finishes are chosen at real prices before the number is set, the biggest sources of overrun are simply gone.
This is also why contingency, useful as it is, is not the answer on its own. Industry rules of thumb put a contingency reserve somewhere around 5 to 10 percent for a well-defined custom build, 10 to 15 percent for a typical one with some unknowns, and higher again for complex or early-stage projects, and the consistent theme across every source is that the reserve shrinks as the design firms up. A contingency is there to absorb the genuinely unforeseeable, not to paper over decisions you could have made up front.
From there, the lever that matters most is the contract. A cost-plus arrangement, where you pay the actual costs plus a fee, leaves the risk of the final number with you, the owner. A fixed-price contract asks the builder to define the whole scope first and then commit to one price to deliver it, moving the overrun risk onto the builder. The comparison piece linked above walks through the two structures in full. The short version is that a fixed price is only as good as the definition behind it, which is why the complete design, the selections, and the soft costs, permits, development cost charges, engineering, and energy modelling, are all carried in the price from the beginning rather than arriving later as unwelcome additions.
Straight Up Construction is built around exactly this: choose everything up front, carry no allowances, and hand you one solid build cost with no surprises. It is the less common model. Most builders in this market run cost-plus and only a minority quote a true fixed price, even though a large share of buyers say cost certainty is precisely what they want. That is an observation from years in this market rather than a published statistic, but it matches what buyers describe the moment they compare two quotes.
The two questions to ask before you sign
You do not need to become a construction expert to protect yourself. Two questions do most of the work, and the answers tell you almost everything about the risk you are taking on.
The first is direct: were they cost-plus or fixed-price? If the answer is cost-plus, you now know the overrun risk is yours, and your follow-up is how allowances and change orders will be handled, because that is where the drift lives. The second is about substance rather than structure: did they provide a real budget with a selections package and a schedule? A firm figure attached to defined selections and a timeline is a builder who has done the work to stand behind the number. A vague estimate with a long list of allowances and no schedule is a number that is still moving, whatever it says at the top of the page. Whichever builder or structure you choose, get every change to cost or timeline in writing, on an investment this size it is simply how you keep the number you agreed to.
The bottom line
Custom builds go over budget for reasons that are almost entirely predictable, and almost entirely preventable. Allowances, change orders, scope creep, unforeseen ground conditions, moving material prices, and soft costs left out of the estimate account for the overwhelming majority of the gap between the opening figure and the final one. None require luck to manage. They require the discipline to define everything up front, price the real home rather than a hopeful average, account for the local realities a mountain build carries, and lock the result into a contract that puts the risk where it belongs. In a place with meaningful permit fees, sizeable development cost charges, an evolving energy code, a serious snow load, and an avalanche corridor between you and your materials, that certainty is not a luxury. It is the thing you are actually buying. If you would like to see what a locked, fixed-price build looks like for your project, Straight Up Construction is glad to walk you through it.
Frequently asked questions
How much do custom homes typically go over budget?
There is no single reliable figure for custom homes, and an honest answer says so. The best homeowner-level data is US renovation data: the 2026 Houzz and Home Study found 37 percent of homeowners went over budget in 2025 against 35 percent who spent what they had planned. Different market, same pattern, going over is more common than coming in under, and the size of the gap depends on how much was defined before the price was set.
What is the biggest cause of construction budget overruns?
Usually an estimate that was too low to begin with, not a change of mind. In the 2026 US Houzz and Home Study, 52 percent of the homeowners who went over budget cited unexpected product or service costs, more than any other reason. Pricing the real selections up front, rather than placeholder allowances that get trued up later, is what removes it.
What is scope creep?
It is the gradual expansion of a project after it starts, the finished basement that was not in the plan, the upgraded kitchen, the wider deck. Each feels small on its own, but together they are a common reason a build passes its opening figure. In the US Houzz study, 31 percent of over-budget homeowners had expanded scope mid-project. A complete design settled before construction is the defence.
How much contingency should I budget for a custom home?
Industry rules of thumb run about 5 to 10 percent of the construction budget for a well-defined build, 10 to 15 percent for a typical one with some unknowns, and higher for complex or early-stage projects, with the reserve shrinking as the design firms up. A contingency is there to absorb the genuinely unforeseeable, so the more complete your design, the less of it you need.
What hidden costs surprise BC home buyers the most?
The soft costs and the local ones. In Revelstoke that means a permit fee starting at $10.25 per $1,000 of project value, development cost charges of roughly $60,000 or more on a single-family home with a secondary suite under the bylaw effective August 1, 2025, energy-code requirements, snow-load engineering for a ground snow load around four times Vancouver’s, and winter delivery delays through the avalanche corridor. None are truly hidden to a builder who works here.
Do rising material prices really affect my build cost?
They can. Statistics Canada reported residential building construction costs rose 3.7 percent year over year in the second quarter of 2025 and were still rising at 2.8 percent in the first quarter of 2026, tying increased volatility in both the pricing and the availability of certain materials to US and Canadian tariffs. A price that was accurate when your estimate was written can move while the project is underway, which is one more reason a firm, well-defined contract is valuable.
Can a fixed-price contract really prevent overruns?
It does not make surprises vanish, it moves the risk of them onto the builder. Once the scope, drawings, and finishes are fully defined, the builder commits to one price to deliver all of it, so if costs move underneath that price, the builder manages it rather than passing it to you. A fixed price is only as reliable as the definition behind it, which is why a complete design and full set of selections come first. For the full comparison, see our guide to fixed-price versus cost-plus contracts.
