During a state code review, the following comment was issued advising the agency (Owner) of a potential difficulty if the architect designed to the code required minimum.
Special Advisory Note to the Agency: The dimensions shown on the drawings for the required lavatory clearances do not allow for any construction tolerances. The dimensions show only the minimum requirements and, often times with this type of dimensions, code violations can occur. Plumbing fixtures clearances are required by the [code] and field corrections become mandatory. Plumbing fixture locations are measured during the [state] Substantial Completion Inspections. Violations of the [state] plumbing code shall be corrected prior to a mechanical recommendation of a TCO.
The review comment essentially states there is no allowance for construction tolerances when measuring minimum dimensions required to comply with the code. So the architect and the agency are put on notice that if the code required minimum 5' - 0" clearance dimension shown on the drawings is built to 4 - 11-7/8", the building will not meet code and will not receive a certificate of occupancy.
So what options do architects have? They could:
- Design to allow for tolerances.
- Mark code minimum dimensions as HOLD or CODE.
Both methods still present a risk. What is an appropriate tolerance and who will enforce exact dimensions?
If the architect allows for a 1 inch tolerance and the contractor builds to a 2 inch tolerance, the building still may not meet code. If a dimension is marked as HOLD, it is imperative that the dimension be shown for the condition governed by the code. For the toilet room example, the dimension must be shown between the faces of the wall finishes, not the stud center lines. Remember wall tile setting beds have a dimension and the contractor may choose use 5/8 inch gypsum board everywhere for convenience even though the drawings show 1/2 inch for the toilet rooms.
Code dimensions also apply to mounting heights. Most building materials are installed before the finish floor is installed so the floor is not damaged. If mounting heights are measured from the structural floor, they may not meet code when measured from the finished floor.
Construction documents normally do not address tolerances affecting code required dimensions. Tolerances are typically specified for specific materials or finishes usually when appearance is important. But perhaps, because of this code enforcement stance, dimensional tolerances should be specified as part of the Division 01 section for quality requirements to help ensure code compliance.