Should I Refinance or Sell My House?

This decision usually arrives the same way. You have equity in your home, the property feels like it’s carrying more value than you’re getting out of it, and the two obvious moves are to sell and take the money or to borrow against it and do something.

Adding a rental unit turns that second option into a genuine alternative rather than just debt. But it only works on properties where it works, and the honest version of this comparison includes the cases where selling is simply the better answer.

The four factors that decide it

Everything reduces to these. If you can answer all four, you have your answer.

1. How much equity is actually available. Not how much equity you have — how much you can access. A conventional refinance typically tops out at 80% of value. CMHC’s product for building additional units reaches higher, but with conditions. Subtract your existing mortgage from whichever ceiling applies and that’s your real number.

2. Whether the lot can support another unit. This is the gate, and it’s binary. Zoning has to permit it, the lot’s dimensions have to accommodate it after setbacks, and servicing has to carry it. If the answer is no, refinancing to build isn’t an option and the decision simplifies considerably.

3. What the new unit would actually rent for. Local comparable rents for a unit of that type and size — not aspirational figures. A below-grade suite rents for meaningfully less than an equivalent above-grade unit in the same neighbourhood.

4. Your own time horizon. Building a unit is a multi-year proposition to repay. If you expect to move within a couple of years, the arithmetic rarely works, because you’ll pay the full construction cost and capture only a portion of it at resale.

Notice that three of the four are facts about your property and market, not preferences. That’s why this decision is more tractable than it feels.

What refinancing to build actually looks like

The mechanism most people don’t know about: you can borrow against what the property will be worth after the work, not what it’s worth now.

CMHC’s refinance product for secondary suites, available since 15 January 2025, allows an eligible owner to refinance to 90% of the as-improved value — above the 80% ceiling on a conventional refinance. The conditions:

• Properties with up to four units, as-improved value below $2 million
• You must already own the home, and you or a close relative must live in it or one of its units
• Funds must go to construction, not equity take-out
• The new unit must be self-contained and code-compliant
• No short-term rental — no letting for periods under 90 consecutive days
• CMHC approval before construction begins

Lenders will typically also count a portion of the projected rental income toward qualifying you — commonly up to half, though this varies by lender and product.

The alternatives are a conventional refinance or HELOC at lower leverage but with fewer strings, or construction financing drawn in stages. Our financing page covers the routes.

What selling actually costs you

Selling looks cleaner than it is. The friction is real and worth counting properly:

• Real estate commission, typically the largest single transaction cost
• Legal fees and closing costs
• Moving costs, and the time the process consumes
• The cost of re-entering the market. If you’re buying again, you pay land transfer tax — which in Toronto means both provincial and municipal land transfer tax — plus the new property’s own transaction costs
• The spread between what you sell for and what an equivalent replacement costs. In a rising market, selling and rebuying is expensive even when the numbers look neutral on paper

On capital gains: a property that has been your principal residence throughout is generally sheltered by the principal residence exemption. That is a genuine advantage of selling, and it’s why “sell and take the money tax-free” is often the instinct.

But there’s an important qualification if you’ve already been renting part of your home, and a trap if you’re planning to.

The tax trap worth knowing before you decide

This one materially affects the comparison and almost nobody raises it.

Where you rent out part of your own home, the CRA’s guidance — set out in its T4036 Rental Income Tax Guide and Income Tax Folio S1-F3-C2 on principal residence — is that you are not treated as having a change in use, provided all three of the following hold:

1. The part of the home used for rental is small in relation to the whole property
2. You make no structural changes to make the property more suitable for rental
3. You claim no capital cost allowance on the rented part

Meet all three, and no capital gain arises on the rented portion when you sell. Fail any one, and you report a capital gain based on the portion of the house that was rented.

Here is the problem: building a proper self-contained secondary suite is generally a structural change. Adding a separate entrance, installing a second kitchen, moving or adding walls — these are exactly the examples given. So a homeowner who converts part of their principal residence into a genuine self-contained rental unit will typically fall outside that safe harbour, and the rented portion can become exposed to capital gains on eventual sale.

This does not make building a bad idea. The rental income and the added property value frequently outweigh it comfortably. But it belongs in the comparison, and it is the sort of thing people discover years later at the worst possible moment. There are elections available in some circumstances — subsection 45(2) of the Income Tax Act can defer a gain on a change of use, though it’s unavailable if CCA has been claimed — and this is precisely the point at which an accountant earns their fee. Talk to one before you build, not after you sell.

(For a fuller treatment of the reporting side, see our guide on reporting rental income from a suite.)

Working the comparison

Here is the structure. The figures below are placeholders to show the method — substitute your own, and treat nothing here as a projection.

Option A: Sell

Option B: Refinance and build

The test in Option B is whether that final line is positive or manageably negative, and whether the added property value justifies the capital deployed. If rent comfortably covers the increased carrying cost, you have converted equity into an income stream while keeping the asset. If it doesn’t, you’ve taken on debt for a unit that doesn’t pay for itself — which is a real outcome and worth identifying before you commit.

When neither is right

Three situations where the honest answer is “do nothing yet”:

The lot can’t take another unit. No amount of financing structure fixes a lot that can’t accommodate a second dwelling. Establish this first — it’s cheap to check and it settles the question.

You’re moving within a couple of years. Construction costs are paid upfront and recovered over years. A short horizon means paying full price and capturing a fraction.

The equity isn’t there yet. If a refinance at 80–90% of value doesn’t produce enough to fund the build, borrowing what you can and hoping to cover the gap is how projects stall half-finished. Waiting is a legitimate strategy.

There’s also a fourth: sometimes people ask this question when the real issue is cash flow rather than strategy, and a smaller intervention solves it. Worth being honest with yourself about which problem you’re solving.

How to get a real number for your property

Everything above turns on four inputs, and all four are knowable before you spend anything: your available equity, whether your lot permits another unit, what that unit would rent for, and what it would cost to build.

HouseLyft’s free property assessment establishes the property side — what your zoning permits, what configurations your lot physically supports, and where the cost drivers sit. Our your options page walks through the paths available to a homeowner in this position, including both of the ones compared here. When you want the numbers for your own address, request your free report. If you’re already leaning toward building and want to test the financing, get qualified.