earshavewalls
Bronze Member
We have a parking garage structure in plan check. The lowest level is below grade. All four sides of the structure are open. The lowest level has been provided with a well that is 5' wide (from face of garage to inside of retaining wall of the well). It is approximately 10 feet from finished grade to the bottom of the air well.
California Building Code, section 406.3.3.1 states that at the openings in the walls around an open parking garage must be at least 20% of the total perimeter wall area of each tier. This is not a problem as we have over 30% on each side. Section 406.3.12 goes on to state that ventilation, other than the percentage of openings specified in Section 406.3.3.1, shall not be required.
Then, we have section 1203.4.1.2: Where openings below grade provide required natural ventilation, the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
Based on 1203.4.1.2, it appears they will need about 15 feet of depth (width) from the face of the building to the opposing face of the retaining wall of the well. There is not enough room on the property to do this without loosing a large number of parking spaces (which they cannot afford to do). The other option, in my opinion, would be to provide mechanical ventilation for the sub-grade level, which would lose some parking spaces, but not many.
I wondered if I was on the right track. They gave me the same story we hear all the time, "We did it this way in THIS/THAT jurisdiction". I don't want to call them on this if there is a way to get past this issue without providing mechanical ventilation or increasing the size of the well.
Any thoughts?
California Building Code, section 406.3.3.1 states that at the openings in the walls around an open parking garage must be at least 20% of the total perimeter wall area of each tier. This is not a problem as we have over 30% on each side. Section 406.3.12 goes on to state that ventilation, other than the percentage of openings specified in Section 406.3.3.1, shall not be required.
Then, we have section 1203.4.1.2: Where openings below grade provide required natural ventilation, the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
Based on 1203.4.1.2, it appears they will need about 15 feet of depth (width) from the face of the building to the opposing face of the retaining wall of the well. There is not enough room on the property to do this without loosing a large number of parking spaces (which they cannot afford to do). The other option, in my opinion, would be to provide mechanical ventilation for the sub-grade level, which would lose some parking spaces, but not many.
I wondered if I was on the right track. They gave me the same story we hear all the time, "We did it this way in THIS/THAT jurisdiction". I don't want to call them on this if there is a way to get past this issue without providing mechanical ventilation or increasing the size of the well.
Any thoughts?