Hi there, sorry about the delay.
The Nest Cam with floodlight is only designed to be installed on vertical surfaces like a wall. It is not designed to be installed on horizontal surfaces because the downward facing angle would reduce the floodlight’s functionality by limiting the field of view of the PIR motion sensor (which triggers the floodlight when motion is detected). Hope this helps and we've also shared your feedback with our team.
Just checking in to see if you still need assistance with this issue. We'll leave this topic open for another 24 hrs in case there are any follow up questions or comments. Please let me know if you need further assistance.