Building Height Methodologies
12000 Government Center Parkway, Suite 551
Fairfax, VA 22035-0065
703-324-3187, TTY 711, FAX 703-324-2010
Sept. 27, 2006
County Accepts Two Building Height Methodologies Up to July 1, 2006
The building industry methodology for measuring building height will be accepted by the county for those single-family dwellings constructed pursuant to a valid building permit issued prior to July 1, 2006. As of July 1, 2006, only the county building height methodology will be accepted.
It has been a longstanding Zoning Ordinance interpretation that the methodology for measuring building height is to first determine the average grade, and then measure the vertical distance from the average grade to the midpoint between the highest roof ridge and its associated eaves for gable, hip or gambrel roofs. The building industry maintains that its long-standing methodology for measuring building height for these types of roofs is the average of the distances from grade points used to determine average grade plane and the height of the roof directly vertical from that point, with the roof heights being the distance midway between the eave of the roof directly vertical from the measured grade point and the roof peak corresponding to that eave.
During the building permit review and approval process, county staff relied on self-certification, a standard practice for various plan approvals, by builders/applicants that the height of the dwelling complied with the Zoning Ordinance. County staff discovered several months ago that the building industry had relied on its methodology in certifying to building height, which was not in accord with the county’s methodology. Once county staff was aware of this issue, a Letter to Industry dated June 29, 2006, was posted on July 1, 2006, to clarify the proper methodology for measuring building height.
Recognizing that a misunderstanding existed within the building industry regarding the proper methodology for measuring building height, the county will accept the building industry’s methodology for single-family dwellings constructed pursuant to a valid building permit issued prior to July 1, 2006. For building permits issued on or after July 1, 2006, the maximum building height will be measured using only the county’s methodology.
The Residential Use Permit (RUP) or occupancy permit is the final county approval in the construction process for a dwelling and allows the dwelling to be occupied. For those dwellings that are under construction pursuant to a valid building permit issued prior to July 1, 2006, and have not been issued a RUP due to a building height issue, required certification of the building height of the dwelling may be based on either the building industry’s or the county’s methodology. All such building height certifications must include a building height field survey and provide the precise calculations used in determining the height and a graphic depiction of the grade and building elevation points used in the calculations.
For dwelling units with building permits issued on or after July 1, 2006, a RUP will not be issued for a dwelling that is in excess of the Zoning Ordinance maximum building height limitation in accordance with the county’s building height methodology. The following procedures have been put into place to ensure such building height compliance:
- County staff independently reviews for building height compliance rather than rely exclusively on self-certification. To assist in this review, all bonded grading plans for single family detached dwellings and all site plans for townhouses must show the actual building height and be certified by a professional engineer, land surveyor or architect licensed in Virginia. The plans must show the spot elevations of the grade around the perimeter of the dwelling, the elevation of the highest roof ridge, the corresponding eave elevations, the midpoint elevation, and the calculations to determine average grade and building height.
- All architectural plans for single-family dwellings must be certified and show the height of the structure from the front stoop or first floor to the midpoint of the highest roof so that information can be cross-referenced with the average grade and overall height certification set forth on the grading plans and site plans.
- Additions to homes that do not require a grading plan also require the applicant to certify to the building height on the architectural drawings and may require a certified field survey of the building height.
- The house model and elevation type must also be provided on the grading plans so that they may be cross-referenced with the building permit. Grading plans that are using an approved master file house plan must provide the ridge and corresponding eaves’ elevations of the highest roof from the approved master file. Custom homes must be labeled as “custom” and are not required to show the model and elevation type.
- Truss drawing packages require a certification from the building designer that the designed building height, as measured from the average finished grade plane to the midpoint of the highest roof ridge, is less than or equal to the Zoning Ordinance maximum permitted building height.
- Cover sheets for architectural drawings require the designer to acknowledge that the designed building height, measured from average finished grade plane to the midpoint of the highest roof ridge, is less than or equal to the Zoning Ordinance maximum permitted building height.
- Upon approval, all plans that propose dwellings with a building height between 33 and 35 feet receive a stamp that a building height certification is required and must be approved by the county prior to RUP issuance. An internal tracking system is being developed to preclude RUP issuance prior to certification approval. The building height certification must include a field survey and provide the precise calculations used in determining the height and a graphic depiction of the grade and building elevation points used in the calculations.
- Additionally, if at any time during the construction phase any dwelling appears to any county inspector to exceed the maximum building height, a letter is sent to the owner/permit holder stating that a building height certification is required and that the RUP or final inspection, in the case of additions, cannot be issued/approved for the dwelling until such certification is approved by the county.
- A review of the grading for general conformance with the approved grading plan is conducted by county site inspectors prior to the issuance of a RUP. For structures that require a building height certification and that receive a winter wavier of final grading and stabilization, permanent identifiable marks shall be made on the structure where the final grade will be established and used to compute the building height. The site inspector will verify that the final grades have been installed and stabilized in general conformance with the approved plan before the conservation deposit is released. Since all dwellings 33 feet and higher will require a field height survey, this inspection will catch any cases where there are large average grade discrepancies and possible height problems.
- The county periodically performs its own building height field survey for verification purposes.
- Training of county staff in the county’s methodology for measuring building height and in the procedures outlined above has been conducted and is now part of an ongoing training program.
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