Rust under windscreens is a common problem.  The biggest issue is that sometimes we only find rust after we have removed the windscreen.

Corrosion like this whilst seemingly small, is right in the point where the pillar meets the body.

The black strip you can see around the edge further away from the rust is the line that we bond the windscreen to.

Where rust or corrosion is present, this area will not be bonded if a windscreen was fitted now.

In this case the client simply had a panel-beater professionally fix the corrosion before we replaced the windscreen. Thankfully the corrosion was in a contained area and was inexpensive to fix.