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We've changed our name! To better describe our commitment to superior service, SI Windows - Phoenix is now

About Capstone Windows & Doors

Capstone Windows & Doors is committed to make sure your experience with us will be your favorite home improvement project. It really starts with installing the finest window replacement product that exists for our climate, Infinity from Marvin. They hand-selected us to be their partner in the Phoenix area market! We offer replacement windows and doors in ScottsdalePhoenix, and Gilbert, AZ. We are a locally owned family business that pledges the principles below:

In-home Consultation

  • Concise discussion of product and design options
  • Vast knowledge about products and industry standards
  • No Commission Salespeople
  • No High Pressure Gimmicks
  • Same-as-Cash and financing options through GreenSky


  • Diligent about dust/mess containment
  • In-house Installation Crews
  • Installation visit from Company Owner
  • Installation process evaluated and endorsed by Infinity from Marvin


  • The heat is gone!
  • Your window coverings will be used only for privacy
  • Your home will be quieter
  • Dust/allergens will be drastically reduced
  • Your great views transitioned to AMAZING!
about us replacement windows in scottsdale az 730x1024

We had an amazing experience with Capstone Windows & Doors. After interviewing 5 or 6 companies, we are so happy with our decision! We’ve already referred several of our neighbors in Rio Verde to them. They took their time to re-design almost all of our window styles to maximize our view! My wife is a realtor and we both understand what a huge improvement this is to our home. -Ron & Nancy, Rio Verde

capstone windows and doors logo

What Our Customers Say

Impressive. Our installers were on time, diligent and courteous. The product is truly superior and high end. We looked for replacement windows for a long time and I felt let down with the high maintenance of wood and cheapness of vinyl. Aluminum was what I thought was the most sturdy and effective but with the heat transference, that was problematic. Enter GLASS FIBER extrusion.

Tim Shanahan

Process was smooth and the installation met all my expectations. I would not hesitate to recommend this company to anyone replacing windows. Greg took the time to go over materials and I was already skeptical about vinyl frames and I’m sure happy we went with fiberglass!

Mark Ellis

We enjoyed working with Infinity. They were precise on their information and dates for installation. Their installer was prompt, courteous and enjoyable to work with. I highly recommend Infinity from Marvin.


Jim Hughett

Let’s build something together.