Replacement Experts

  • Windows
  • Patio Doors

  • Folding & Multislide Patio Doors

  • French Doors

  • Front, Back, & Side Doors

  • Reduce Energy Bills

  • Improve Security

  • Reduce Outside Noise

  • Improve Curb Appeal

  • No Dry Wall or Stucco Damage

  • One Day Custom Installation

  • Torrance, CA Showroom

Cornerstone Windows 25 years in business

Replacement Experts

  • Windows
  • Patio Doors

  • Folding & Multislide Patio Doors

  • French Doors

  • Front, Back, & Side Doors

  • Reduce Energy Bills
  • Improve Security

  • Reduce Outside Noise

  • Improve Curb Appeal

  • No Dry Wall or Stucco Damage

  • One Day Custom Installation

  • Torrance, CA Showroom

Cornerstone Windows banner - Serving the South Bay for 25 years

Replacement Experts

Your home is a family’s biggest financial investment. Replacement windows, entry doors, french doors, and sliding and swinging glass patio doors are proven and cost effective way to improve your home’s value, beauty, energy efficiency, security and reduce outside noise.

In business since 1999, Cornerstone installs products from the industry’s premier companies; Simonton, Win-Dor, Milgard, and Masonite. All products are expertly installed and include exceptional warranties, including a double lifetime warranty.

Cornerstone’s installation system allows most projects to be completed in one day with no drywall or stucco damage. Protecting your home and furniture during the installation process is always a priority.

Cornerstone offers a free, no pressure consultation as well as free visual estimates.

Hurry! Summer Savings!Hurry! Summer Savings!

Manufacturer’s rebate on windows and patio doors

Call now for more details!

Simonton offers on windows and patio door rebates

Our Projects

brand new windows installed

Cornerstone uses only full-time employees. There are no sub-contractors. This maintains a high level of quality control and a seamless installation process. Most jobs are completed in one day!

We are proud to be voted a South Bay Favorite for Windows & Doors in 2022, 2021 and 2020 by readers of the Daily Breeze!

Cornerstone Windows & Patio Doors - 2022 Daily Breeze South Bay's Favorite Window Door Company
Cornerstone Windows & Patio Doors - 2021 Daily Breeze South Bay's Favorite Window Door Company
Cornerstone Windows & Patio Doors - 2020 Daily Breeze South Bay's Favorite Window Door Company

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Tony Szik's Cornerstone Doors & Windows, Inc., Door Installation, Torrance, CA

Transform your home with new windows & Doors!
Contact us today for a FREE estimate

Simonton offers on windows and patio door rebates
Cornerstone Windows banner - Serving the South Bay for 25 years

Cornerstone Windows & Patio Doors

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Cornerstone Windows will be in touch as soon as possible to discuss your project