https://articlescad.com/using-....a-cat-flap-in-bifold
A favorite choice for homeowners A composite door cat flap provides an easy entry point for your pet. It also lowers the chance that unwanted animals will gain access to your home. However, adding a cat flap to your composite door requires experience and knowledge of the door's composition. Any structural modifications could compromise its integrity and impact its thermal performance. Install a cat flap on a composite door A cat flap allows your pet to leave and enter the house without letting in other animals or cats