E-1 C15-2022-0042 LATE BACKUP - CITY STAFF PRESENTATION — original pdf

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2212 Trailside Drive May 9, 2022 - Board of Adjustments meeting 1 E-1/1-LATE BACKUP/PRESENTATIONSubchapter F Intent • • Subchapter F is intended to minimize the impact of new construction, remodeling, and additions to existing buildings on surrounding properties in residential neighborhoods by defining an acceptable buildable area for each lot within which new development may occur. The standards are designed to protect the character of Austin's older neighborhoods by ensuring that new construction and additions are compatible in scale and bulk with existing neighborhoods. 2 E-1/2-LATE BACKUP/PRESENTATIONSubchapter F Requirements Prior to 2006, a house was only limited by: • 35’ height • 40% building coverage • 45% impervious cover • • Subchapter F introduced a 40% floor-to-area ratio (FAR) or 2,300 square feet of gross floor area (GFA) and reduced the height to 32’. For Subchapter F, GFA is all enclosed space, regardless of its dimensions, that is not exempted under subsections 3.3.2, 3.3.3, or 3.3.4. 3 E-1/3-LATE BACKUP/PRESENTATIONSubchapter F Exemptions 3.3.3 – Porch exemption 3.3.2 - Parking area exemptions 3.3.3 – Basement area exemption 4 E-1/4-LATE BACKUP/PRESENTATIONSubchapter F Exemptions (cont.) 3.3.3 – Habitable Attic exemption All of the following criteria must be met: fully contained within the roof structure. 1. The roof is not flat or mansard roof; slope of 3:12 or >. 2. 3. has only one floor. 4. does not extend beyond the footprint of the floors below. 5. highest habitable portion of the building, or a section of the building, and adds no add’l mass to the structure. 6. 50% or > has a ceiling height of 7’ or < * * See BOA code interpretation C15-2011-0110 5 E-1/5-LATE BACKUP/PRESENTATIONSubchapter F Enclosed Area 3.3.4 – Enclosed area w/ height 5’ or < An enclosed area shall be excluded from the calculation of gross floor area if it is five feet or less in height. For purposes of this subsection: A. Area is measured on the outside surface of the exterior walls; and B. Height is measured from the finished floor elevation, up to either: 1. 2. the underside of the roof rafters; or the bottom of the top chord of the roof truss, but not to collar ties, ceiling joists, or any type of furred-down ceiling 6 E-1/6-LATE BACKUP/PRESENTATIONPrior BOA Interpretation 7 E-1/7-LATE BACKUP/PRESENTATIONCeiling Height Ratio • C15-2011-0110 and BCM 4.4.5.2 (4) make it clear that the ceiling height ratio used in attic calculations is measured in accordance with subsection 3.3.4. • Ceiling height is measured from the finished floor elevation, up to either: • The underside of the roof rafters; or • The bottom of the top chord of the roof truss, but not to collar ties, ceiling joists, or any type of furred-down ceiling. 8 E-1/8-LATE BACKUP/PRESENTATIONScissor Truss determination • The top & bottom chord are in close proximity to each other • Determination was particular to a project and especially noted furring down a ceiling in order to mitigate future use of the determination for roof configurations similar at 2021 Trailside. • Conventional shed roof framing is a 2x that spans the bearing points. • If the shed portion of the roof at 2021 Trailside was framed in a conventional manner, this discussion would be moot. 9 E-1/9-LATE BACKUP/PRESENTATION2212 Trailside Drive Second story general floor area Counted towards gross floor area Not counted towards gross floor area Area of house in question 10 E-1/10-LATE BACKUP/PRESENTATION2212 Trailside Drive Front exterior elevation 11 E-1/11-LATE BACKUP/PRESENTATION2212 Trailside Drive General location of attics 12 E-1/12-LATE BACKUP/PRESENTATION2212 Trailside Drive Right-side elevation 13 E-1/13-LATE BACKUP/PRESENTATION2212 Trailside Drive General location of attic 14 E-1/14-LATE BACKUP/PRESENTATION2212 Trailside Drive 15 E-1/15-LATE BACKUP/PRESENTATION2212 Trailside Drive Ceiling height is measured from the finished floor elevation, up to: • The underside of the roof rafters; or • The bottom of the top chord of the roof truss, but not to collar ties, ceiling joists, or any type of furred- down ceiling. 16 E-1/16-LATE BACKUP/PRESENTATION2212 Trailside Drive Truss diagram • T3 is the top chord. • Height is to be measured to the bottom of the top chord, T3. • Does not match building section. 17 E-1/17-LATE BACKUP/PRESENTATIONInternational Residential Code (IRC) • The IRC is the technical building code for residential structures and pertains to building safety. • The Land Development Code (LDC) is a zoning regulation for mass, scale, and compatibility. • The technical building code requirements of the IRC do not invalidate the additional criteria that must be met for a zoning exemption. • Subchapter F zoning regulations are about all enclosed space regardless of if it is habitable or not. 18 E-1/18-LATE BACKUP/PRESENTATIONResult of Appeal • If the BOA approves the appeal and Residential Review requires exempted habitable attics to only meet the criteria found in IRC R326.3, and not the BOA Code Interpretation, then: • Some attics would be classified as a story above grade plane and would not even qualify. • Attics would be limited to much smaller floor areas. • Attics would be permitted at much larger heights. • Zoning reviewers will be required to review for two different codes. 19 E-1/19-LATE BACKUP/PRESENTATION2212 Trailside Drive • The gross floor area exemption is an option that will not be viable for every attic. • The exemption is particular to habitable spacing. As such, non-habitable space is not to be exempt. • Removing the ceiling height requirement established by C15-2011- 0110 and BCM 4.4.5.2 (4) would result in roof masses that are significantly taller and larger. • While the proposed attic in the subject project does not penetrate the tent, eliminating the ceiling height ratio requirement would permit much larger fully exempted attics that could be outside the tent. 20 E-1/20-LATE BACKUP/PRESENTATIONThank you 21 E-1/21-LATE BACKUP/PRESENTATION