Since 1981, Sandau Construction Co., Inc. has been serving the greater Twin Cities Metro area with premier windows, siding and home remodeling services. Our long history of experience in quality workmanship and customer satisfaction gives every homeowner the ability to complete their projects with confidence. Free Estimates. Remarkable Results. We’re sure you will be delighted with your new windows, doors, siding or home remodel — especially with free estimates and terrific savings on vinyl windows, siding and stone!