Wall Kit Installation Instructions *IMPORTANT HI* Whenever cutting through walls, caution should always be taken to avoid Gas, Electric & Plumbing Lines. Note: We recommend two persons to complete installation (Steps the Pet Door is not already installed, cut opening and drill holes using template provided with your pet door Outside of Pet Door frame Diagram 1 inside of Pat Door frame V-Grooved Edge Sections {Snap off as needed) Diagram 2 Step #1. Measure wall thickness.