Ask three contractors what a basement costs and you will get three very different answers. Published prices in Ontario run from $35 to $130 a square foot, which on a 700 square foot Whitby basement is anywhere from $24,500 to $91,000. That gap is not us being vague. It is the market genuinely not agreeing with itself.
Whitby divides neatly for this work. Brooklin, Taunton North and West Whitby are newer, with full height basements that are ready to frame. Down toward the lake it is a different job. Werden’s Plan, the grid laid out in 1854 between Colborne, James, Brock and Henry, is mostly houses from the 1850s through the 1950s, and that is where low ceilings, old wiring and asbestos era materials turn up.
These are the prices other companies publish, not ours. We show you where each one comes from so you can judge it yourself.
| Scope | Published range | What that range rests on |
|---|---|---|
| Basic finish, no bathroom, about 700 sq ft | $24,500 to $91,000 | Contractor estimates spanning $35 to $130 per sq ft |
| Adding a three piece bathroom | Add $15,000 to $35,000 | Contractor estimates, a spread of nearly six times |
| Legal second unit, permits included | $50,000 to $180,000 | Contractor claims. Building permit records for basement suites declare a median nearer $25,000 |
| Lowering the floor or underpinning | $30,000 to $100,000 | 17 permit records for underpinning with finishing, median $60,000 |
Pulled from published Ontario contractor prices and municipal permit records on 1 August 2026. We show you the full spread instead of picking an average, because the sources really do disagree by up to four times, and two of the bigger ones turned out to be publishing the same numbers as each other. Your price comes from a free visit, fixed, with HST already in it.
That is Whitby’s own fee for a 1,000 square foot basement. When a quote shows three or four thousand for permits, most of it is drawings and engineering. Those are real costs, but they belong on their own line so you can see what you are actually paying for.
Until the end of March 2027 the town reimburses the building permit fee, the registration inspection, the curb cut and the below grade entrance on an added dwelling unit. Worth knowing before you decide whether the basement is a family room or an apartment.
Registering an added unit in Whitby is $268. If the town finds out through a complaint instead, it is $534. That is a simple reason to do it properly the first time.
For a rental unit in a house that already exists, the rule is 6 feet 5 inches, not the 7 feet people quote at you. Plenty of basements written off as too low actually pass. It takes two minutes with a tape measure to find out.
Most of the town is clay loam, sandier toward the east. Water moves slowly through clay, which is why damp turns up here more than people expect. Durham will lend you $3,000 interest free for a backwater valve and sump pump, paid back on your water bill.
If the home went up before 1990, the law puts this on the owner rather than the contractor. You have to have the materials checked and give the report to anyone quoting. Around Werden’s Plan and the older streets off Brock, that is most of them.
Give us the address and a time that works for you. No sales pitch and no waiting on a callback.
Ceiling height, damp, wiring, where the drain sits, and what the rules allow for what you actually want. About 45 minutes.
Written down, HST included. If there is anything we cannot price without opening a wall, we say so next to the number instead of hiding it.
One free visit, one fixed price, HST included. No sales pitch and no callback loop.
Book my free visit