Can they install the windows from inside only without having to work from outside?

Most window installations require both interior and exterior access for proper installation, weatherproofing, and finishing work. However, there are some situations where interior-only installation is possible with certain limitations.

Interior-only installation can work for specific scenarios like replacement windows in accessible ground-floor locations where the exterior trim and siding don't need modification. This typically involves insert-style replacement windows that fit within the existing frame opening. The installer can handle the interior removal, fitting, insulation, and interior trim work from inside, but this approach has significant limitations.

Why exterior access is usually necessary: Professional window installation requires exterior caulking, weatherproofing, flashing installation, and exterior trim work to prevent water infiltration and air leaks. The exterior sill, brick mold, and siding connections are critical for long-term performance and energy efficiency. Without proper exterior sealing, you risk moisture problems, drafts, and potential structural damage over time.

Ottawa's climate considerations make proper exterior weatherproofing even more critical. Our freeze-thaw cycles, heavy snow loads, and temperature extremes demand complete perimeter sealing that's difficult to achieve from interior access alone. Ice damming and wind-driven rain can exploit any gaps in exterior weatherproofing.

When interior-only might work: Some insert replacement windows in ground-floor locations with simple exterior trim may be manageable from inside, but this limits your window options and may compromise energy efficiency. Upper-floor installations, bay windows, or full-frame replacements virtually always require exterior access for safe, proper installation.

For the best results and warranty protection, plan for both interior and exterior access during your window installation. Professional installers have the equipment and experience to work safely at height when exterior access is needed.