GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Forming concrete for garage – best practice to keep rain out

mikeysp | Posted in General Questions on

Hi. In zone 4a I am getting ready to form up for a monolithic slab and want to identify the best practice for keeping rain water from getting into shop under garage door.

In the image below I illustrated two ides I have gathered from online images or videos. It seems the cutout method with maybe a 1″ drop would be best, but I am not certain.

Thank you for your advice.



GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. walta100 | | #1

    Garage floors are sloped to drain to the door about 1/8 of an inch per foot, if you can maintain or increase that slop outdoors for next 20 feet.

    The details in your drawing will be unnecessary.


  2. krom | | #2

    Walter.. That is the theory but even with those slopes, or steeper, wind driven rain finds its way into my garage on a regular basis

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |