Open Air Garage . Typical sidewall exhaust fan within enclosed parking garage. For a side to be considered open, the total area of openings along the side shall be not less than 50 percent of the interior area of the side at each tier and such openings shall be equally distributed along the length of. OpenAir Garage on Modern Home HGTV from photos.hgtv.com Hill farm design / black side gate: It’s important if you have two cars or a very large car to strongly consider a single garage door in place of two individual ones. Even the travel distance to an exit can be increased to 120 metres from the 45 metres the national building code.