French patio doors vary widely in size, construction, and installation requirements. Common widths range from 1,200 to 2,400 millimeters, while heights often reach 2,100 millimeters. Always measure the finished opening, not only the existing door panel. A few millimeters can affect sealing, drainage, and installation labor. Metric and imperial dimensions may not convert perfectly. Check the manufacturer’s rough-opening chart before placing an order.
Standards deserve careful attention. Look for verified air, water, wind, impact, thermal, and safety-glass performance where required. Local building codes may differ between coastal regions, cold climates, and high-wind zones. Ask for test reports, certification numbers, and the glass specification in writing. Low-E glass, insulated frames, and multipoint locks can improve comfort, but they raise the purchase price. Freight, customs charges, local taxes, unloading, and professional installation can add substantially to the quoted door cost.
Warranty language needs equal scrutiny. Confirm coverage periods for frames, hardware, glass seals, finishes, and labor. Some warranties exclude coastal corrosion, incorrect installation, condensation, or unauthorized modifications. Transfer rules may also matter if the property is sold. I once saw a budget estimate that ignored delivery equipment and site preparation. The final cost changed sharply. That mistake is easy to repeat. Request a complete landed-cost quotation, installation guidance, spare-parts availability, and a written response-time policy before comparing the top ten options.