Abstract: An exhaust box used to ventilate rooms or devices within a building to the ambient environment. The exhaust box has a generally rectangular main body portion, with an exterior end and an interior end and is adapted for installation in the wall structure of the building. An inlet portion projects from the interior end and is adapted to receive an exhaust duct in sealed relation thereto. A flange portion extending radially outwardly from the exterior end of the main body portion helps retain the exhaust box in place within the wall structure. The main body portion has a bottom portion that is sloped downwardly towards the exterior end so as to cause water to flow towards the exterior thereof. A damper member is pivotally attached to the exhaust box so as to be gravity biased into place against a receiving surface at the interior end of the inlet portion.