A-1 Siding and Windows Niagara Ltd. Has been in business for over 17 years. What started as a small home business in Thorold, is now proudly serving the Niagara and Hamilton regions. Our team of experienced craftsmen is proud to give your home the care and detail it requires in order to exceed your expectations. We guarantee all our work and look forward to providing you quality workmanship and detail that are as unique as your requests.