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1-905-738-1870

Made in Canada

Made in Canada
4.7/5 HomeStars Rating
300K+ Happy Customers
45+ Years in Business
Non-Prorated Lifetime Warranty
ENERGY STAR Certified Products
Adam Kwasnicki, Service Representatives - Clera Windows & Doors

Adam Kwasnicki

Our local representative has been serving the GTA and surrounding areas for over 15 years!

1-844-738-7936

Contact us for more information and about a free quote!

Our Local Clera Branch Serves Thornhill

As the manufacturers and installers of all our windows and doors, we stand behind our work.

professional window replacement service

Limited Time Offer

Get Up to 30% OFF All Replacement Windows & Doors

No Interest, No Payments for 18 months!

Book a Free Consultation
High-Quality Windows & Doors

Plus Get $600 per Window in Free Upgrades

With our wide range of ENERGY STAR products, you can be sure to save big on your next dream project!

Instant FREE Upgrade to Brilliance Line
Don’t pay for 18 months from Installation Date
Low Monthly Payments Available

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Hung Window, Gallery Image - Clera Windows + Doors

Single & Double Hung Windows

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  • Easy-clean tilt function – Easily clean exterior glass from inside your home
  • Space-saving design – Perfect for narrower lots and condo spaces
  • Ultimate ventilation control – Adjust top, bottom, or both sashes to direct airflow
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Vinyl Awning Windows - Clera Windows + Doors

Awning Windows

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  • Superior weather seals – Triple-sealing system creates airtight weather barrier
  • Rain-or-shine ventilation – Top-hinged and opens outward to let air in, not water
  • Break-in resistant – Harder to force open thanks to secure multi-point locking
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High-Quality Windows & Doors

End Vent Slider Windows

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  • Unobstructed city views – Slim frames and large glass panels maximize glass area
  • Dual sliding sashes – Enjoy fresh air from both ends of the window
  • Effortless operation – Smooth rollers allow for seamless opening and closing
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Best Vinyl‍ Double & Single Slider Windows - Clera Windows + Doors

Double & Single Slider Windows

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  • Horizontal sliding – No swing-out clearance needed 
  • Lift out sashes – Easily lift out panels for quick, hassle-free cleaning
  • Sleek design – Clean lines and a minimalist frame for a modern look
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Speciality Shaped Window, Gallery Image - Clera Windows + Doors

Specialty Windows

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  • Custom shapes & sizes – Match door and window style to your home’s aesthetic
  • Light without limits – Brighten hard-to-fit spaces with precision-crafted glass
  • Energy-efficient materials – Tailor-made for insulation and UV protection
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Best Vinyl‍ Bay & Bow Windows - Clera Windows + Doors

Bay & Bow Windows

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  • Dramatic visual impact – Create depth and dimension to any space
  • Extended interior space – Add a cozy nook or built-in bench 
  • Panoramic light & views – Let the outside in with multi-panel layout
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Fixed Windows Installation

Fixed or Picture Windows

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  • Maintenance-free – No moving parts means no fuss, no wear
  • Zero energy leaks – Keep drafts and energy bills down
  • Frameless views – Large glass area for scenic backdrops and natural light
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Contemporary Window Solutions

Casement Windows

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  • Maximum airflow – Hinged on the side and opens outward for full ventilation
  • Tight-locking design – Multi-point locking system keeps out drafts and intruders
  • Sleek crank handle – Easy to open in kitchens or behind furniture
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Steel Security Doors

Steel Entry Doors

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  • Reinforced steel construction – Built for strength, durability, and top-tier protection
  • Smooth, low-maintenance finish – Resists rust, dents, and wear
  • Energy smart – Foam-insulated core helps keep your heating bill in check
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Designing Your Fiberglass Door - Clera Windows And Doors

Fiberglass Doors

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  • Environmentally friendly – Get the look of wood without harming the environment
  • Built for Canadian weather – Stands up to moisture, dents, and daily wear 
  • Superior insulation – Keep your home cozy no matter the weather
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Patio Sliding Doors

Sliding Patio Doors & Garden Doors

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  • Unlock natural light – Expansive glass panels brighten your space beautifully
  • Smooth-gliding operation – Glides open with ease and locks up tight
  • Extend your indoor living outside – Effortlessly blend your home with your patio or garden
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Exterior Storm Doors

Storm Doors

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  • Enhanced weather protection – Shield your entryway from rain, snow, and wind
  • Customization – Available in clear, ventilated, and decorative glass options
  • Secure ventilation – Keep insects out and fresh air in
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Frequently Asked Questions

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professional window replacement service

Replacement Windows & Doors Thornhill

Replacement Windows & Doors Thornhill

Adam Kwasnicki, Service Representatives - Clera Windows & Doors

Adam Kwasnicki

Our local representative has been serving the GTA and surrounding areas for over 15 years!

1-844-738-7936

Contact us for more information and about a free quote!

Contact Us

Our Local Clera Branch Serves Thornhill

As the manufacturers and installers of all our windows and doors, we stand behind our work.

Adam Kwasnicki, Service Representatives - Clera Windows & Doors

Adam Kwasnicki

Our local representative has been serving the GTA and surrounding areas for over 15 years!

1-844-738-7936

Contact us for more information and about a free quote!

Contact Us

Our Local Clera Branch Serves Thornhill

As the manufacturers and installers of all our windows and doors, we stand behind our work.

Clera Windows + Doors

Thornhill, Markham, Vaughan, Richmond Hill, and Surrounding Areas

Toll Free: 1-844-738-7936
Phone: 1-844-738-7936
Fax: 905-738-0586

Sales: sales@clerawindows.com
Service: service@clerawindows.com

Clera Windows + Doors

Toll Free: 1-905-738-1870
Phone: 1-905-738-1870
Fax: 905-738-0586

Sales: sales@clerawindows.com
Service: service@clerawindows.com

Get a Quote
Best Windows And Doors - Clera Windows + Doors

Get up to

$600 per Window

in FREE factory upgrades

With our wide range of ENERGY STAR products, you can be sure to save big on your next dream project!

Learn More
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Limited Time Offer To Upgrade Your Home - Clera Windows + Doors

Replacement Windows & Doors Thornhill

Thornhill is a beautiful suburban neighbourhood in the Greater Toronto Area and home to over 110,000 residents. Located along the northern border of Toronto and split between the cities of Vaughan and Markham. What once was Ontario’s police village, an area that did not permit the development of a town, is now a thriving community for families, schools, local newspapers, and sports teams. Home to great restaurants, entertainment, places to shop, parks and recreation. Places like The Promenade mall and Conley Park South are the popular places for residents and visitors to enjoy during their time off.

For residents, being encompassed in all the great things Thornhill has to offer, you’ll want your home to reflect the beauty of it all with top quality windows and doors. Having beautiful windows and doors gives your home the utmost aesthetic appeal, creating a more vibrant and polished look for your visitors and community to admire. Fortunately, Clera Windows and Doors is an industry leader in both quality of work and customer service. Beyond instantly modernizing your home, new windows and doors can be a great remedy for soundproofing your home as well as provide better insulation to save you money and reduce greenhouse emissions in the winter.

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As a family run company since 1978, you can be assured that we understand and appreciate the importance of any home renovation project to your family. We’re in the business of providing comfort and security for households across Canada, and we couldn’t be more grateful for all the homes and families that have entrusted us with such an important decision to improve their home’s functionality and security. All of our fenestration installation technicians are rated by the Canadian Standards Association and our products are all ENERGYSTAR rated as well, so you know our work can be trusted. We’ve also taken home the “Top Choice Award” and are so confident in our craftsmanship that we include a written, lifetime factory warranty on our products. What this means for you is that you won’t have to buy another pesky replacement part again!

Customized Windows & Doors In Alliston - Clera Windows + Doors
Invest In Your Home Today - Clera Windows + Doors

Why Choose Clera

Why take a chance with other window or door companies that purchase their products from another supplier, only to resell them to you for a higher cost?

Clera Windows + Doors is one of Canada’s largest, oldest, most dependable and reputable vinyl window manufacturers in Ontario. We fully manage and take care of your door and window replacement project from start to finish, ensuring every stage of your window or door project meets our lofty standards of craftsmanship.

Why are we Ontario’s most awarded window and door company?

The Clera Care Guarantee Logo

Over 45 Years of Experience

With over 45 years of experience, we have earned a reputation as one of Canada's leading window and door manufacturers and installers.

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Certified Technicians

You can trust our team of factory trained technicians to install your new windows perfectly—our A+ BBB rating is no accident!

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Serving Ontario With over 40 Branches

We have over 40 branches across Ontario, which means that we're always close by when you need us.

Non-prorated Lifetime Warranty Icon

Non-prorated Lifetime Warranty

Whenever anything goes wrong with your windows, we'll take care of it for you—no questions asked.

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ENERGY STAR® Certified

Our hung windows meet Canada's strict energy-efficiency standards. A window from Clera is not only high-quality and durable, but also energy-efficient.

Reasons to Love
our Products

Clera Windows + Doors is a reputable vinyl window manufacturer in Ontario with a history of dependable and high-quality products. Our superior materials and cutting-edge technology ensure durability, energy efficiency, and style. We offer customizable styles and colors, as well as superior security features and noise reduction technology to provide the best possible product attributes for your home.

Our team manages every stage of your replacement project, from start to finish. We work closely with you to understand your specific needs and preferences, and use our extensive experience and knowledge to deliver a solution that exceeds your expectations. Trust Clera Windows + Doors for exceptional service and expertise for your home renovation needs.

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Energy Star Approved

Effortless Operation Icon

Modern, Contemporary Design with more glass, and less frame

Better Home Security Icon

Better home security

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A quieter home; improved noise reduction from the outdoors

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No Maintenance Icon

No maintenance: vinyl windows are virtually maintenance-free

Pilkington Low-e Glass Technology Icon

Pilkington Low-E Glass Technology, engineered specifically for Canadian climates

Structural Integrity Icon

Wet-glazed frames and sashes on all windows; the ultimate in protection against water and wind infiltration, with added structural integrity

Improved Ventilation Icon

Triple-fin weatherstripping with built-in anti-microbial properties, meaning no mould and better air quality

Pure Virgin UPVC Icon

100% pure virgin UPVC, providing protection from fading

Exceptional Durability Icon

Stronger hardware and structural integrity thanks to integrating galvanized steel (allows for larger, more spectacular views!)

If you’re situated in the Thornhill, Markham, Vaughan, and Richmond Hill areas, you’ll find Clera Windows and Doors at 31 Hughson Drive in Markham. To book a free consultation or to get more information on new replacement windows and doors for your home, call Clera Windows and Doors at 1-844-738-7936 or follow these driving directions:

  1. Continue onto the Don Valley Parkway N for 13.5 kilometers.
  2. Continue onto ON-404 N for 8.7 kilometers.
  3. Use the right 2 lanes to take exit 27 for Highway 7 toward Richmond Hill/Markham/ON-7 for 800 meters.
  4. Use the right 2 lanes to turn right onto York Regional Rd 7 (signs for Markham/Highway 7 E) 900 meters
  5. Turn left onto Woodbine Ave/York Regional Rd 8 (signs for Regional Road 8/Woodbine Avenue) 300 meters
  6. Turn right onto Lunar Crescent 290 meters.
  7. Turn left onto Hughson Drive, look for 31 Hughson Drive. The destination will be on the left.
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Window & Door Assemblers - Clera Windows + Doors
Best Vinyl‍ End Vent Slider Windows  - Clera Windows + Doors
Vinyl Windows & Doors - Clera Windows + Doors
Bay & Bow Windows - Clera Windows + Doors
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Meet The Team - Clera Windows + Doors
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