6 Questions to Ask Before Choosing a Window & Door Supplier

Replacing your windows and doors is one of the biggest and most impactful investments you can make in your home. It’s an opportunity to improve your energy efficiency, enhance security, and completely transform your home’s aesthetic. With so many suppliers and installers to choose from, knowing who to trust can feel overwhelming.

But the key to a successful project and a beautiful, long-lasting result is right at the beginning of the journey: asking the right questions upfront. 

At Sternfenster, we understand that choosing new windows and doors for your home is a significant decision. You deserve confidence and peace of mind from start to finish. A reputable and professional company, like one of the many within our Approved Installer Network, should be more than happy to provide clear and detailed answers to any questions you have.

To help you along your journey, here are seven crucial questions to ask any prospective window and door supplier:

1.What Materials Do You Use, and Are They Certified?

Not all windows and doors are created equally, and the quality of the materials directly impacts the product’s performance, durability, and lifespan. 

At Sternfenster, we’re proud to be a multi-award-winning manufacturer of uPVC and aluminium windows and doors, and all of our products are made with the highest quality materials to meet stringent industry standards for Great Britain. Since we manufacture our own products, we can provide a complete history of the materials used, guaranteeing they meet the highest quality and safety standards.

2.What is the Installation Process and Timescale?

A great product can be let down by a poor installation. 

However, when you choose a Sternfenster Approved Installer, you can have peace of mind that you are choosing a professional who will be transparent about their process. They should walk you through every step, from the initial survey to the final clean-up, and provide a clear timeline for the project. This professionalism ensures that your home is treated with care and respect throughout the entire installation process.

3.How Do You Ensure the Security of Your Products?

In 2025, home security is a top priority for any homeowner when it comes to choosing the right product for their home improvement project. Our windows and doors are designed with security at the forefront. We use robust uPVC and aluminium profiles, resilient double glazing, and the latest multi-point locking mechanisms. 

Many of our products meet the Secured by Design standard, a police-backed initiative that shows a product has passed rigorous security testing. For extra peace of mind, our Secureplus guarantee offers homeowners compensation if a break-in occurs due to a hardware failure.

4.What Warranty Do You Offer, and What Does It Cover?

A strong warranty demonstrates a company’s confidence in its products and the quality of its workmanship. We offer a robust warranty that gives you peace of mind, covering both our high quality products and the professional installation by our Approved Installers. 

Be sure to get a clear, detailed breakdown of the warranty’s duration and what it covers, as a clear warranty is a sign of a trustworthy company.

5. Can You Provide References or Showcase Previous Work?

A company’s past work and customer feedback speak volumes about its reputation. We encourage you to ask your installer to show you a portfolio of their previous work or provide references from recent customers.

 You can also explore reviews left directly by previous customers on independent review sites and social media pages, to see what other homeowners are saying about their service and the quality of our products.

6. Are Your Installers Qualified and Insured?

The people who will be in your home are just as important as the products they are fitting. Sternfenster works with a network of Approved Installers who are meticulously vetted for their skills and professionalism. They are certified, have industry-specific training, and are fully insured. By choosing one of our Approved Installers, you’re choosing a professional who will ensure a higher standard of work and greater accountability.

Partner with Sternfenster Today

By asking these questions, you can cut through the noise and make a confident, well-informed decision on your next home improvement supplier. 

The right supplier, like a Sternfenster Approved Installer, will be a partner in your home improvement project, providing not just quality products, but also expert advice and a professional service from start to finish.

Get in touch with the friendly and experienced team at Sternfenster today, find an installer near you on our website, or start your online quote to make a confident start to your home transformation journey.