Clera Windows + Doors Bowmanville is the leading supplier of custom replacement windows and doors. Family owned and operated since 1978, we manufacture all our pieces in our Ontario warehouse so that we can maintain the highest levels of quality and craftsmanship. We offer a range of styles and designs to suite any aesthetic, allowing you to match your replacement windows and doors to your decor. Family owned and operated since 1978, we manufacture all our pieces in our Ontario warehouse so that we can maintain the highest levels of quality and craftsmanship. We offer a range of styles and designs to suite any aesthetic, allowing you to match your replacement windows and doors to your decor.