This list ranks 10 basement renovation companies in Markham, ON. It starts from Google Maps searches for basement renovations and related building work in Markham: 132 firms were checked, and building and renovation firms with their own website and an open Google listing went forward. Firms are weighed on their Google rating, the number of reviews behind it, how closely their services match basement renovation, and their portfolio. The strongest firm overall sits at place 1, places 2 and 4 carry a badge for what each suits best, and the rest run in order. Ratings and review counts are Google's, checked October 14, 2026. How we rank
Owner-led Markham renovation contractor doing basement and bathroom renovations, with more than ten years in the trade.
Toronto and GTA renovation company doing basements, bathrooms, kitchens, stairs and full-home remodels, from North York to Vaughan and Thornhill.
Construction company in Markham taking on basement renovations and general construction work.
Toronto and GTA contractor doing kitchen, basement and bathroom renovations and commercial build-outs, plus decks, landscaping and snow removal.
GTA basement finishing company that handles design and construction, plus basement bathrooms, kitchens, fireplaces and built-in shelving.
Toronto and GTA renovation contractor finishing basements and building basement apartments, alongside kitchen, bathroom and full-home renovations.
| Rank | Firm | Best for | Services | Google rating | Area |
|---|---|---|---|---|---|
| 01 | A & J Renovation | Owner-led basement and bathroom work | Basement renovations · Bathroom renovations | Rated 4.9 out of 5 from 98 Google reviews | Scarborough, serves Markham |
| 02 | Ahoora Home Renovation | Basement rental suites | Basement renovations · Bathroom renovations · Kitchen renovations · Stairs renovations · Wall removal | Rated 5.0 out of 5 from 43 Google reviews | Thornhill, serves Markham |
| 04 | TipTop Renovations | Basement framing and drywall | Basement renovations · Kitchen renovations · Bathroom renovations · Commercial renovations · Decks | Rated 5.0 out of 5 from 26 Google reviews | Based in Richmond Hill |
| 05 | HTR Basements | Full basement finishing with 3D design | Basement finishing · Basement design · Basement bathrooms · Basement kitchens · Built-in shelving | Rated 4.8 out of 5 from 26 Google reviews | Based in Richmond Hill |
| 06 | Basement Finishing Company | Basement apartments and finished basements | Basement finishing · Basement apartments · Kitchen renovations · Bathroom renovations · Full home renovations | Rated 4.6 out of 5 from 58 Google reviews | Based in Concord |
| 07 | Assured Basements | Basement finishing with detailed 3D plans | Basement renovations · Basement finishing · 3D floor plans · Project management | Rated 4.5 out of 5 from 162 Google reviews | North York, serves Markham |
| 08 | Let's Renovate | Basements with separate entrances, plus repairs | Basement renovations · Separate entrances · Full house renovations · Home additions · Custom cabinetry | Rated 5.0 out of 5 from 9 Google reviews | Markham |
Five things to confirm with any firm, on this list or not, before you sign. The rules below are Ontario's and Markham's.
Ask the firm for a clearance certificate from the WSIB, which confirms it is registered for workers' compensation and its account is in good standing. The certificate confirms the firm is registered with the WSIB and up to date on its premiums, so check its dates cover your job.
Ask for a certificate of insurance that names the firm and shows commercial general liability coverage in force for the dates of your job, and check that the subcontractors it brings in are covered too.
Building permits for homes in Markham come from the City of Markham, and finishing a basement or adding a secondary suite usually needs one. Agree in writing who applies for the permit and books the inspections.
Get the scope of work, the payment schedule tied to stages of the work, start and finish dates, how changes are agreed and priced, and who handles permits and cleanup, all in one signed contract before any work starts.
A renovation is not a new home, so the new home warranty rules usually do not apply: get the firm's own workmanship warranty in writing, with what it covers and for how long. Renovators in RenoMark, the Canadian Home Builders' Association program, offer a minimum two-year warranty on their work.
The 10 firms on this list fall into 3 groups, read from what each firm's own site says it does and how it is listed on Google.
Basement specialists work mainly on basements, from family rooms to secondary suites.
Renovation companies renovate existing homes, one room at a time or all of it at once.
General contractors run building projects of many kinds and bring in the trades each job needs.
It is the term Alberta builders and homeowners use for finishing an unfinished basement: framing, insulation, electrical, plumbing, drywall and flooring, often with a bedroom, bathroom or family room. Elsewhere it is usually called a basement renovation or basement finishing.
In many Canadian cities, yes, but a legal secondary suite has to meet the building code and local zoning, including a separate entrance, ceiling heights, fire separation, smoke alarms and egress windows. It needs a permit and inspections, so ask the firm whether it has built legal suites in your city.
Deal with water before finishing: grading and downspouts that carry water away from the house, a working sump pump where the house has one, and repairs to foundation cracks. Then insulate and frame in a way that handles moisture. Ask the firm what it checks before it starts framing.
Usually. A basement bathroom needs a drain connection, which can mean breaking the concrete floor to reach the main drain, or a pump system where the drain sits higher than the floor. The plumbing work needs a permit and inspection.
Ask the firm for a clearance certificate from the WSIB. The certificate confirms the firm is registered with the WSIB and up to date on its premiums, so check its dates cover your job.
Building permits for homes in Markham come from the City of Markham. For basement renovation, finishing a basement or adding a secondary suite usually needs one. Many firms apply for the permit as part of the job, so agree who does it before you sign.
What finishing or developing a basement costs in Toronto, Calgary, Edmonton and Vancouver in 2026: prices by size, add-ons, permit fees and the big-ticket scopes.
What a legal basement suite, second unit or basement apartment costs to build or legalize in Calgary, Edmonton, Toronto and Vancouver in 2026, and which code items set the price.
The code and zoning rules a basement suite, second unit or basement apartment has to meet in Ontario, BC and Alberta: ceiling height, fire separation, alarms, exits, heating and how many units a lot can hold.
Send the detail that is out of date, or the name and website of a firm that belongs here.
