TL;DR: Cornerstone was great from beginning to end. From my first phone call, to the time it took for them to call me back, to the final installation, Cornerstone was friendly and professional. I strongly recommend this company. ---------- If there were 10 stars, Cornerstone would deserve all of them. A burglar shattered the glass of the Simonton dual-pane sliding door that I had purchased from Home Depot 12 years ago. The lifetime warranty from Simonton was one of the main reasons I purchased their windows. When I contacted Simonton for the warranty claim, they sent me a list called "Find a Pro". It was 4:30 pm on a Friday afternoon, and all of the other pros on the list either didn't answer the phone or only were only willing to service windows that they installed themselves (mine were installed by the Home Depot contractor). When I called Cornerstone, Tony answered the phone and was so kind to me every second of the way. (When does the boss answer the phone? I lucked out!) He was confident that the warranty would cover the shattered glass, and told me he would call Simonton and call me right back. I told him I had called Simonton many times, and since they operate on East coast hours and close at 2 pm EST, they had already closed for the day. Tony informed me that Simonton has a plant in California. Tony called me back in less than half an hour. As promised, he was able to reach Simonton on a Friday afternoon and order the window efficiently. Cornerstone didn't even have to come and measure my window; Tony was able to look up my order number (located on a sticker on another window) in the system to find out the exact size I needed. Tony said he would call me back when the window arrived in 2-3 weeks. I would have to live with my boarded-up sliding door for 2-3 weeks, but Cornerstone seemed like it would be worth the wait - the other Yelp reviews I read were stellar! Well, on Monday (the next business day), I received a phone call from Tony. He had my sliding door in stock, and sent Jacob to install it first thing in the morning on Tuesday. I have birds, so the 7-7:30 am timeframe was not a problem for me. Anyway, the sooner the better - not being able to use that sliding door was a huge inconvenience! Jacob arrived on time and was friendly and courteous. He introduced himself, was wearing a company t-shirt, and I saw the sliding door in the back of his truck. Before removing the plywood that was boarding up my window, he measured the door to make sure he brought the right one. As expected, it fit perfectly! Jacob carefully cleaned up all the broken glass that had fallen down into the sliding door track, and even cleaned up the dust under it that had accumulated in the track over time. When he replaced my sliding door, he kindly removed the lock from the old sliding door and installed it onto my new sliding door. My door lock had been a little difficult to use even before Cornerstone replaced the sliding door. Jacob replaced the stripped screws and adjusted the metal piece that the lock latches onto, so now it works great! I use that door at least a dozen times a day. Even though he didn't need to work on the screen as part of replacing my shattered glass sliding door, Jacob repaired one of the screen wheels that was not rolling very well. Everything moves very smoothly now. He even polished the window before he left. He asked me to test it before he packed up his tools and drove off. What I really appreciated about Jacob was that he answered all of my questions patiently, regarding the glass material, the frame material, sliding door maintenance, etc. It took Jacob only about an hour to replace the sliding glass door and check all of the other parts of the door. If all businesses were as skilled and as nice as Cornerstone, Tony, and Jacob, the world would be a better place. I would not hesitate to call Cornerstone again should the need arise, and will go out and ask my local friends if they're in the market for a new window or door, so I can tell them about Cornerstone. read more

I had recently purchased a home and needed help with two windows. I had an excellent appointment with the tech.

Don't call cornerstone unless you need product AND installation. Apparently they don't sell product unless you want to pay them to install which is fine but there's a better way to say it instead of being rude on the phone with potential customers. read more

I placed a call to Cornerstone after the glass to one of my patio (metal) sliding doors shattered. Tony took my call, asked me for details, and then proceeded to explain that they don't replace just the glass. He said they do vinyl doors and he gave me details on his proposed replacement. He also mentioned that the city where I live is quite strict with permit requirements and recommended I check on that, too. I was transparent with Tony that he was the first call I made and that I'm not sure what option will currently work for me. Despite that, he provided me a quote (decent price) and a timeframe of project start date and told me to decide and call him back should I choose to go with them. Although I didn't get a chance to work with Tony and this company at this time (the only reason this review is not a 5 star), the great customer service I received over the phone is enough for me to consider them when we do decide to go with vinyl doors. Thank you, Tony! Hope to be able to have a project done by your team some time in the future. More power! read more

We learned about Cornerstone from our neighbors who'd had first-rate experience with Tony and Cornerstone over many years. It turned out to be a great experience for us, too, relying on Cornerstone to replace our home's worn out windows, entry & patio doors. Tony and Tammy were a pleasure to communicate with at every stage of the project. The crew they sent for installation were also clearly "the best." Antonio and Jake did a fantastic job throughout the house, taking things apart/putting everything back together in absolutely high-skilled, professional, and punctual fashion. We'd recommend this company highly to anyone interested in finding someone with the experience and knowledge to demonstrate they know very well what they're doing in the field of window/door replacement - and be willing to do it at a fair price. Many thanks, Cornerstone! read more

These guys are so wonderful and family owned! Tony runs a great company with long term employees. My installers were Antonio (work with Tony for 18 years) and his son Jake (12 years). The quality of their work was so impressive! Removing and installing the new windows caused quite the mess, but Antonio and Jake left my house exactly how they found it. Which I can not say the same for other work done around my place. They were very communitive and responsive. Professional and really friendly. They have installed 6 of our 7 units in our complex in Redondo and have increased the value as well as upgrading the look. I couldn't be happier with the windows, sliding glass doors and the over work completed. They provide such a great sound barrier and help keep the heat in. I highly recommend Cornerstone. read more

Cornerstone has THE best service, quality & value bar none! We've been doing business with Tony and his excellent company for decades. They aim to please! read more

The crew topped themselves this time when we went back to order a new higher UV large picture window plus install crank-out side windows and then swap out another large side window for a slider that gives us so much afternoon breeze. The entire house is cooler in more ways than one. Tony went above and beyond to get us installed on the same day the product came in. Can't give them all high enough marks. They have made their mark in the Hollywood Riviera specifically and in the South Bay in general. Next project: A new front door. Already have it scoped out! read more

Cornerstone Windows & Patio Doors - Windows Installation Near Me - Torrance, California

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We highly recommend, and so happy to have partnered with Cornerstone Windows for our window and door replacement. Their pricing is fair and competitive, and their service is top notch, from initial sales to installation. Throughout the process, Cornerstone was always responsive (we had many questions!), and installation was seamless, the new windows upgraded our older home, insulating against weather and sound conditions. Family-owned, professional, and providing the highest quality work ... we're so pleased with the end result! Thank you Tony and the entire team at Cornerstone! read more

WE COULD NOT BE MORE PLEASED WITH OUR DOORS!!! We chose Cornerstone Windows & Patio Doors to replace our front and kitchen doors. Our home is 79-years old and to do this right, the doors needed to be custom made. Tony, the owner recommended, we selected fiberglass versus wood. It's difficult to see the difference and they will last decades. The many choices of styles and fixtures were our toughest choices to make! Tony's team, Antonio, Jake and Mike were very professional and respectful. They worked so well together. Tony delivered 100% and has been serving the greater South Bay for 25+ years and we highly recommend him. read more

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Cornerstone was recommended to us by a friend and I'm glad we took their suggestion. Tony and Jacob (father and son) are super easy to work with and their entire team did a fantastic job. They were crystal clear with communicating what needed to be done and the timeline. You can stop by their workshop to see their products as well. Their windows are high-quality and I highly recommend them. read more

Cornerstone Windows & Patio Doors - Window - Windows Installation Near Me - Torrance, California

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Second time having Tony, Antonio, and the crew come out to replace windows. The reason we wanted Tony to come back and handle this project was because we knew we would be getting great quality of work and great customer service in an efficient manner. Not only did they do amazing work, they also spent extra time making sure the area was clean after install, which was much appreciated. While we had questions regarding size and placement of window prior to install, through Tony's suggestions, we are beyond happy with our new window! Highly recommended! read more

My husband and I are starting a huge remodel in South Torrance, already have an architect plans and general contractor. I wanted to start narrowing down doors and maybe consider windows. If you are starting the process for looking window or door replacements, then avoid Cornerstone. I visited the office today and when I asked if he had sliding doors on display, Tony the owner said it was 45 minutes away. Of course I wasn't going to drive 45 minutes away at the moment, and said no thank you. He did point me to a corner that had the materials of the sliding doors he offered, but didn't walk around to discuss it. My husband had some questions for doors, as this was his first experience at any Window Door store. Sadly Tony did not welcome any questions because automatically judged us that we weren't doing business with him. That's what he told us. Additionally, , he clearly said I won't quote you if you don't have the measurements and we told him the measurement is 12 foot with a standard height sliding door, but he refused to discuss further. Lastly, I had to tell him while I was leaving "you don't have to be so rude." He started being rude back to me. Regardless if I am a woman/man/child/new customer/returning customer, his unprofessionalism is uncalled for. I have never experienced this kind of service from Window + Door company. Or any small or big business for that matter. We own multiples properties in Torrance and never experienced this type of negative service. After feeling deflated, we drove around the corner to One Stop Windows and Doors who answered all are questions, gave us a quote on 12' wide x standard height door on different vendors within the hour. read more

To anyone considering Cornerstone, feel free to message me. I'll be happy to give a reference with a lot more details of what happened, now that the inspections and repairs of the work he left behind for me to deal with are complete. I encourage you to verify everything with Tony, especially what he wrote in his reply, and judge for yourself. read more

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Cornerstone is the best! They replaced three sets of French Doors a few years ago, and not only were they beautiful then, but they still are! They've held up very well. I just had them replace an outside closet door that was a disaster. The frame was leaking and causing water to enter the house. The gap between the bottom of the original closet door and the floor was uneven as it's on a balcony and the floor slopes to allow water to drain properly. Tony (the owner), Antonio, Mike, and Jake were all wonderful! They are super nice. The door looks fantastic. They built a brand new frame for the new door that looks terrific also. Given the slope of the floor, they did an amazing job building a level threshold. It all looks great! And it's leakproof!!! Thank you so much Cornerstone!!! Do not hesitate to call them. read more

I used Cornerstone for a tricky curved window replacement project. From the beginning Tony was great to work with. The install team is excellent and I brought up an issue and they were quick to fix it. We also had some dry rot and they were able to make the windows and the surround look like new. I'm so happy I found Tony and his great team. Would hire them again!! read more

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This is my second review of Cornerstone. I have actually purchased more windows and doors for my remodel. I also purchased all of my hardware as well. Cornerstone did not disappoint on any of the 3 times that I have worked with them. Tony knows his stuff for sure and always dependable and informative. Tina is in the front office and always very helpful. The crew that comes out for installation is also very knowledgeable, polite and makes sure everything is clean before leaving. Jake came out a few times during our process of things and he makes sure that everything is completed to Cornerstone standards. I wish all of the contractors that I worked with during my remodel had the same standards and ease as Cornerstone. I would HIGHLY recommend this company. read more

From their Yelp reviews, I knew they'd be good. But still, I was apprehensive (meaning scared half to death). Because....I've replaced window glass before but never big picture windows including the frame. I expected broken glass everywhere, worried about my cat impaled on shards....all kinds of worst case scenarios. But...nothing bad happened. No mess, no glass shards. I feel a bit foolish. Speaking of the cat, he started this whole thing. A neighbor's cat comes around at night to taunt my indoor cat thru the windows. I heard loud crashing sounds one night, only to discover my cat hurling himself against a window, his entire body, to get at the other cat whom he now hates with a passion. My cat is ready to fight for his territory. Then, after weeks of cat pounding on a big window that's probably original to my old house...a crack in the glass appeared. And slowly got bigger. No point in replacing just the glass. The old aluminum frames were shot. Cornerstone to the rescue. Rob came out (on time) to tell me the cost & take measurements. I let him decide the style of windows cuz he certainly knows more about this than I do. His recommendations turned out to be perfect. He's great. I met Maggie in the office when I dropped off the deposit check & have spoken to her since. She's great, too. I didn't get any other estimates, btw, had already made my decision before Rob arrived based on the reviews, a contractor's recommendation, and the fact that Cornerstone is local. And their price seemed very fair, as I expected. I decided to do both windows in the room instead of just the cracked one. Cornerstone has its own crew, nothing is farmed out. That's important to me. Antonio & his crew of two came (on time) to do the job. And what a wonderful job they did. My new fancy-schmancy Simonton energy efficient windows-with-the-works are gorgeous. Much too good for this old house when compared to some of the other original windows. So I'll likely replace more old windows at some point. And an exterior door. I now have sliding panels (with locks) on the new windows for more ventilation. And new screens of course. The whole room is brighter. And the room is cleaner than it was before the crew got here. No mess whatsoever. These installers are pros. And nice guys. The day I had stressed over ended up being fun. To my cat: You cannot break these hurricane-resistant windows so knock yourself out, kiddo (not literally I hope). On second thought.....knock yourself out. read more

Cornerstone Windows & Patio Doors - Windows Installation Near Me - Torrance, California

Tony and his team are great! They have put in new windows at several houses we own. He is experienced and you will be satisfied.

Tony and his crew did an amazing job on our windows and doors. They were professional and courteous from start to finish. You can tell immediately that they really know what they are doing and are there to get the job done right. Cornerstone made our home look beautiful and preserved the old craftsman style of our house. Their products are high quality, they are super skilled and very enjoyable to work with. We couldn't have asked for a better experience and I will be recommending them to everyone I know. read more

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I got bids from five or six window companies before selecting Cornerstone. Their bid wasn't the cheapest, but I liked the style of the windows and their bid included tempering three of the windows because of their location, while for the other companies it would have cost even more than the original bid. Jacob and his team arrived on time and were friendly and professional. They did the installation in 5-6 hours, cleaned up after themselves and caulked everything with clear silicone, so there's no messy look on the outside. I'm happy with the look of the windows, and I would definitely recommend Cornerstone to friends and family. read more

We just had four windows and four patio doors replaced by Cornerstone. I did receive a few estimates and decided to go with Tony at Cornerstone. Their pricing is very competitive. The crew of Antonio and Mike were punctual, polite, and cleaned up daily. Everything went smoothly from start to finish. Always felt comfortable throughout the entire project. They really do give you a hometown vibe. I was happy to support a local business. Very happy with my new windows! read more

Just had the Cornerstone crew out again this year for a new project replacing an outside entrance door to the garage. Antonio checked with me in advance and verified everything I requested. I like Cornerstone because they do the job right the first time. The door was exactly what I wanted and was perfectly installed straight plumb and level. Looking forward to using Cornerstone again in the near future. They show up on time and do an amazing job with minimum noise. They left the place cleaner than when they arrived! read more

Just had 12 windows, a French door, sliding door, and Dutch door installed at our house. 3 full days of hard work! Antonio and Mark were on time every day at 7am as they said they would be. Antonio, Mark, Jake and Tony were amazing, kept everything clean as they went with very little clean up from me at the end. Things ran very smoothly and they were very professional. We had quotes from other companies and decided this was the best value for our money and we are so thrilled we went with them. Our house looks new with the addition of new windows and doors, it's amazing what an upgrade like this does! Thank you so much for a great experience and we have already recommended a few people to you! read more

I had lived with two failed porthole windows for years. I couldn't find a window company that wanted to deal with them, too risky that surrounding siding and stucco will come out with the window. Out of desperation I went to next door for a recommendation and Cornerstone was mentioned by a neighbor. They were terrific to work with. Got a quote within days and the project was completed without a hitch in about four hours. I will recommend these folks without reservation. I wouldn't have known they had been working here when they left, they are fastidious about cleaning up after themselves when they finish. read more

Love my patio door. Anthony and his partner did the best job. Very respectful. Did my windows some time ago, also very happy still.

We had all 20 windows and a slider replaced with Cornerstone in 2016 and can only say wonderful things regarding picking out windows, the installation and how everyone we dealt with was helpful and efficient in the installation. We had a little water intrusion yesterday on a window with this crazy weather and all I can say is wow. Once again they were helpful and handled the situation. Their employees are wonderful. Thank you, Cornerstone. read more

Tony and his team did an absolutely fantastic job helping us choose and install our new windows and patio doors. We obtained a few quotes and chose Tony based on his knowledge about the city and his products, along with his fair prices for the quality products he sells. He knows all of the city codes and rules, which put us at ease. Tony came first to measure our windows. He was very professional and knew our building well. We provided us with a fast quote and pulled the permit for us. He set our appointment and let us know what to expect. On the day of installation, his team showed up on time and wearing masks, which was very important to us. His lead Antonio was very professional and let us know what to expect and how long the project would take. They did an amazing job with the installation - we could not be happier. The team was wonderful. We are so happy with the windows and sliding doors. They look amazing and Tony and his team were so enjoyable to work with. I would absolutely recommend and use Tony for any project in the future. read more

I was referred to Cornerstone and Tony by my realtor when I bought my house in July of 2021. My house is a fixer upper, and all the windows and back slider were ancient and in desperate need of an upgrade. Tony was awesome from the beginning. He educated me on brands/styles/functionality and helped me with my decision making process. Me being new to all things windows I went through the learning/exploratory phase and he was patient with all the questions I had & changes I made prior to placing my order. On install day I was very happy with the professionalism and workmanship of his installers. Antonio was the lead installer and was communicative throughout the install which I always appreciate. It's refreshing to have everything go right from beginning to end. Thank you Tony and team! read more

Tony and his team are a class act! Extremely professional, efficient, provide quality products and are fairly priced. The installation itself was quick, and they left the place cleaner than when they first came! We love our new windows and sliding glass doors. i had noted some very small(!) imperfections with the screens and Antonio immediately offered to replace them. Within a few weeks, Tony returned to install the new screens and even went out of his way to help improve the operation of an older bathroom window that we hadn't replaced. I wish all service providers were as professional and well-run as Cornerstone. Thank you!!! read more

Very competent and efficient and they do installation of the product also. Time will tell how the windows hold up but they look nice. I would recommend them to a friend or family. read more

Tony & his team are fantastic! They were courteous, prompt and tidy. Prices were very competitive. Our install went in 2wks early. The head installer, Antonio was knowledgeable and figured out some tricky spots on our older home. Excellent service, I highly recommend them. read more

Tony and his team recently installed new windows and front doors in my three-unit condo building. Cornerstone's customer service is top-notch - Tony was extremely communicative and happy to answer any and all questions. It was only a few weeks from order to install and when his crew arrived for install day, they were on time, friendly and incredibly efficient. I was amazed at how quickly they worked. I'm excited to enjoy my beautiful new windows and doors for years to come! read more

I have to thank Tony and his crew for a fantastic window replacement install. I couldn't be happier with the new windows installed today. Tony was a pleasure to work with picking out the windows best suited for my home. His crew was exceptional. I can't say enough about Cornerstone. My family has been going to Tony for a number of window installs and they never disappoint. If you are looking for replacement windows you can't go wrong with Cornerstone. Thank you Tony and your crew read more

I left for work this morning and came home to a house of BEAUTIFUL NEW WINDOWS. Masked workers. Super professional. And it took 2 minutes for my house to be cooled by the A/C as opposed to ...never... with my prior windows. I love my windows. I love that it was done in 1 day. I love my new screens. I'm just STOKED! read more

We replaced two sliding patio doors. After speaking with two other companies, we selected Cornerstone. By far they were the easiest to do business with and we're the most competitive cost-wise. Jacob was very responsive, accommodating and friendly during the entire process. Installation was on time, very professional and again, all members of the team were friendly and enjoyable to work with. I would definitely work with Cornerstone again and recommend them to anyone looking to replace windows and doors. read more

After a lot of research, we went with Tony and Cornerstone for windows in our entire house. Tony and his team were fantastic to work with and we highly recommend them for your needs. What a huge difference new windows make! Tony listened to our needs and installation was smooth and easy. The team was professional, clean and kept the disruption in our home to a minimum. This was our first time replacing windows and Cornerstone was a pleasure to work with. read more

This was my first time replacing my windows on a home. Tony, Rosio, and team were professional, timely, and courteous in getting the estimate and scheduling the job. When they arrived at 8AM to replace 13 windows, they said they would be done by 5PM. And they were. The job was impeccable and the windows added new life to the home. Thanks Tony and team. read more

I live in an 80's condo in Redondo Beach that needed updated patio doors, as the existing ones I were warped aluminum, not insulated, etc. I received estimates from every window vendor I could find in our area. I ended up going with Cornerstone Windows and Doors and I am very happy with their work and the quality of the product. (A similar window from Renewal by Anderson was twice the price. Milgard does NOT warranty windows within 2 miles of the beach, which no one tells you.) I went with Simonton Daylight Max patio sliders and transoms. They difference is incredible. It is 20 degrees cooler in my west facing living room. The windows look beautiful, and the work was completed in one day. The crew was efficient and polite, and owner Tony Szik supervised the job himself. Great company to work with, honest, fair pricing, quality products. I highly recommend them! read more

So glad we went with Cornerstone! It is a local business that knows the area and house styles and has been in business for a long time. We got bids from six other window installers, but we liked Tony, the owner, because he told us the pros and cons about the products we were choosing, and he never rushed us through an appointment. When the installers arrived, it was a seamless operation from start to finish. The guys were on time, neat in appearance, wore masks, were helpful and ready to answer any questions we asked and finished when they said they would. They kept the house in perfect order, cleaning and sweeping every bit of debris. When they were done, it was almost like they had never been there, except we had new windows! We highly recommend this company! read more