Meet the
Cornerstone Windows Team

Meet the Boss

Tony Szik

Cornerstone Windows & Patio Doors founder and owner, Tony Szik, has been in the home improvement industry for over 44 years. From full home construction to customized remodels and now, window and patio door replacement.

The company’s meticulous pre-sight measuring system results in installation projects with no drywall or stucco damage. Most jobs are completed in one day.

Cornerstone uses ONLY full-time employees-NO sub-contractors.This staff continuity maintains a high level of quality control and a seamless installation process.

Tina Szik

The friendly voice you hear when you call Cornerstone’s belongs to office coordinator, Tina. She manages the mountain of paperwork which flows through the office on a weekly basis. From incoming deliveries, project scheduling to answering the phone and emails, Tina is an integral member of the Cornerstone team.

Antonio Aguirre

Antonio Aguirre has been with Cornerstone Windows since 2006. After receiving project specifications from the sales department, Antonio serves as onsite foreman, coordinating removal of old windows and doors to custom installation of all purchased products. Antonio’s professional onsite demeanor creates an atmosphere of trust with homeowners.


Reputation is critical for a local business like Cornerstone. Word-of-mouth reviews and repeat customers are the keys to success and growth in the South Bay area of Los Angeles. Consistently high customer reviews on YELP and Angie’s List solidify the company’s high standing in the home improvement industry. Cornerstone is a proud member of the Better Business Bureau.

Cornerstone Windows banner - Serving the South Bay for 25 years


Cornerstone’s approach to sales is low pressure. We respect your time and promise to keep sales presentation low key and focused.

We find out what the potential customer wants, educate them on the options and process, then present a precise proposal.

Customers are encouraged to research other companies and products. Our staff is available to answer questions: (310) 325-4700.


Our Commitment Spans From Everything To The Value Of Our Products To The Craftsmanship Of Installation

Our commitment to supplying customers with the finest windows and doors is backed by our dedication to customer satisfaction. Contact us for a free estimate at (310) 325-4700 and start enhancing your home’s beauty and value today.

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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