Costello windows, doors and conservatory collection are designed to be beautiful, convenient and efficient. Aiming for a minimal need for care and maintenance and servicing requirements. This being said our help center is on hand to answer any query you have and help you may need.

General Maintenance

Windows and doors need regular cleaning and maintenance to keep them weatherproof and in good working order which saves money! If they’re not maintained, problems can occur such as sticking, rot or corrosion. Some maintenance tasks are common to all windows and doors. Others depend on the material the window is made from.

Costello Windows Moving Parts Guarantee

Moving Parts

The common interest of the customer and the manufacturer is that the product fulfils all its functions correctly and for a long time. For this, the manufacturer has to follow the right manufacturing technology and the customer has to use the product according to its purpose and maintain it regularly.


In order to ensure free opening and closing of windows and doors, it is recommended to oil or grease all moving parts of the fittings once to twice per year. Acid-free and resin-free grease or oil must be used, for example, the common home appliance oil, Vaseline, petroleum jelly or equivalent will keep the locking mechanism in good working order.

Costello Windows Guarantee
Costello Windows Guarantee


Block open fireplaces with a loose-fitting removable panel when not in use. The loose fit allows any rain that gets in to evaporate away. On extractor fans and range hoods, check shutters are working properly. Check your ceiling hatch is correctly fitted to reduce draughts.