Why Cornerstone Windows & Patio Doors
Is Different

woman cleans single and double hung window with tilt feature - easy cleaning

All we do is replace windows & doors!

Installing high-quality replacement windows and patio doors improves your home’s beauty, minimize outside noise, and reduce heating and air conditioning bills.

Here’s why Cornerstone is different:

  • Serving the South Bay since 1999
  • Owner, Tony Szik, has over 40 years of contracting experience
  • Fully licensed, bonded, and insured
  • NO subcontractors – only Cornerstone employees
  • Products are purchased directly from the manufacturer – no middlemen
  • All windows & doors are custom manufactured to fit your home
  • Cornerstone practices all health and safety precautions required by the CDC and local health departments.

We offer a large selection of high-performance products in the following categories:

  • Vinyl Windows
  • Fiberglass Windows
  • Aluminum Windows
  • Patio Doors – swinging & sliding
  • Entry Doors
  • French Doors

Our Commitment

Our commitment spans from everything to the value of our products to the craftsmanship of installation.

Transform your home with new windows! Call (310) 325-4700 or contact us today for a FREE in-home estimate.


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