I basically have the following type of back door:

![enter image description here](https://i.stack.imgur.com/3XPMt.jpg)

The problem is that my girlfriend moved in with me. Well not, really, her dog did and we need to install a pet door. The problem is I need the first row of glass to be made of wood in order to be able to install the door in.

I thought of replacing the bottom row of glass with wood panels, then once they set, cutting into them to fit in the door.

What kind of wood should I use to make sure that it is weather proof. Assuming this isn't a dumb idea.