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HomeMy WebLinkAbout09042008 BSC Agenda Item 5 r . Joint Preliminary Report Zoning and Planning Commission (ZPC) & Building and Standards Commission (BSC) August 29, 2008 Subiect Basements/Underground Structures Background Recently, City Planner, Debbie Scarcella, alerted the ZPC and BSC to the fact that builders in West University Place are beginning to include subterranean structures (basements) in their projects. In the past year or so, three separate permit applications have included either partial or full basement structures. The city's zoning regulations (Code of Ordinances, Appendix A) and building and development regulations (Code of Ordinances, Chapter 18) do not specifically address regulating such structures. The International Building Code and International Residential Code include specific technical regulations when constructing the structures, but do not address such issues as location on the building site, proximity to property lines, maximum depths, uses of the space, etc. The city's floodplain regulations address basements in a special flood hazard area, but not in the non-hazard areas of the city. After preliminary discussions and research into the existing regulations, the ZPC and BSC have concluded that basements present potential risks to both property owners and occupants, and the city's ordinances should be amended to address them. Philosophically, there are two approaches the city can take. The first would be to institute a broad prohibition of subterranean structures by simply not allowing them. The second would be to allow them within strict regulations. Prohibition To take the broad prohibition approach, the city would need to amend specific sections of the Code of Ordinances, either through the zoning regulations or building and development regulations and building codes. There are definite pros and cons to this approach. Pros 1. Simplicity. Would add very little to the Code of Ordinances. Removes/resolves nearly all questions (e. g., proximity to property lines, possible impacts on adjoining properties of narrow sites, lateral and subjacent support of structures, flooding, emergency egress, framed area, number of stories). 2. Helps control density and intensity of use and the possible increased burden on city infrastructure. 3. Creates uniformity across the city as to the impacts on flood risks and fire safety. Basements are already prohibited in the 100-year flood plain. Cons 1. Possibly encroaches on the rights of property owners. 2. Prevents some traditional uses of subterranean spaces (e.g., storm or wine cellar, mechanical equipment, storage, etc.) Allow. But Regulate Pros 1. Gives property owners more flexibility in how to use their property (protects property owner's rights). 2. Might bolster the tax base by increasing the appraisal and creating a more desirable property for someone who would prefer, for example, a basement mechanical area or wine cellar. 3. Could act as a possible storm cellar when weather conditions deteriorate, or allow other desirable traditional uses. 4. Regulations would contribute to making the spaces safe from flooding and fire. Cons 1. Possible impact on neighbors, especially on narrow lots that utilize a full basement approach. 2. Possible impact on density and infrastructure by placing an extra burden on utilities, parking and traffic, etc. 3. Increases property-damage and personal-safety risks in a flood situation or fire.The ZPC and BSC have discussed and developed additional issues to consider if the allow-but-regulate approach is taken. These issues are listed in the attachment to this report. Action The commissioners and staff seek direction from City Council regarding appropriate action on this subject, including the choice of approach. We look forward to discussing this topic in a workshop session with City Council, if desired. Best Regards, Steve Brown, Chair ZPC Bryant Slimp, Chair BSC List of Concepts and Guidelines Excavations and Underground Structures August 14, 2008 At the meeting on July 10, 2008, the Zoning and Planning Commission comprised a list of agreed upon concepts and guidelines to use in possible regulation development regarding excavations and underground structures. Two basic concepts that will apply to all of the possible regulations are: 1. Keep regulations Simple and straightforward 2. Look to pool construction rules for guidance The basic purposes of the regulations seem to be centered on protection of adjoining properties and safety of the structures and its occupants. The following concepts and the areas of responsibility between ZPC and the BSC, as well as affected code references are listed below: Zoning and Planning Commission {ZPC} [Zoning Regulationsl A. Second form of egress (window) to the rear of property only. (ZPC) [Article II Definitions; Table 7-2 Setbacks; or Table 7-6 Projections] B. Basement may only be located beneath building footprint. {ZPC] [Table 7-2 or Table 7-6] -C. Basement may not be located in an easement. {ZPC] [Table 7-2 or Table 7-61 D. Basement may not be located closer than 5 feet to the side property line. {ZPC] [Table 7-2] E. Does not count as pervious area (for underground structure located in a front or rear yard). (ZPC} [Table 7-6] F. Limit framed area and number of stories (based on increased density and possible impact on infrastructure). {ZPC] [Article II Definitions of Framed Area] G. Limit basement area to 50% of area of floor above {ZPC) [Article II Definitions-either definition of basement or half-story] H. Restrict uses and occupancies (storage and non-sleeping area only){ZPC] [Article II Definitions] Building and Standards Commission {BSC] [Chapter 18 Development Regulations and Appendix C - Technical Codes Schedule] A. Special engineering and hydrostatic pressure questions {BSC] [Technical Codes and Drainage Regulations - Chapter 18] B. Drainage provisions must be included {BSC] [Drainage Regulations-Chapter 18] C. Sill heights for egress from basement areas {BSC] [Technical Codes] D. Require a wider staircase (for safety/egress) {BSC] [Technical Codes] E. Sprinkler requirements for the structure (BSC) [Technical Codes - Fire and/or Building Code] F. Assume it will flood and protect against consequences {BSC] [Chapter 18 - Flood Prevention Regulations] G. No sanitary facilities below grade (BSC) [Technical Codes - Building and/or Plumbing Code; Flood Prevention Regulations] H. Vertical (inside) access only (no ramps or exits to outside) {BSC] [Flood Prevention Regulations] EXCAVATIONS AND UNDERGROUND STRUCTURES The key issues regarding excavations and underground structures are as follows: 1. A. Should the underground stricture project into the yards and if so, then how much? Should the excavation area be allowed to project into the yards? (ZPC) Table -b of the Zoning Re",-ttladons lists those items allowed to project into the regulated ;ards. ndergtround items are not restricted at all as to the ].milts of 1lic.ir. uncroa,:hme.rrt .nto these \'ards. Conceivably. a baserxrent would technically be :allowed to ,,pan t!►e ntire building site front. property line to property line unrestricted. B. Should underground structures be allowed on narrow lots taking the 3n alternate side yard exception? Narrow lots (less than 55' wide) are liven an option to use alternate side yard`. This is iili» ed to tincourage rear situated gara >es. It a strt.tcture built i.tnclenzi-ot►nd on a marrow site is constructed when taking the alternate side setback allowance. should there be 1i►nits and restrictions on. the proximity of the basernerrt wall and the excctvatiort to :.ICijoirring property lines. 2. If an underground structure is allowed in the yard areas, should there be special rules for lot drainage regulations? (BSC) t.~Ia<tpter 1.8 provides regulations for btlildin<~ site drainage anal controlling the -unotf mate ase:d our a 1." per hour rainfall. Slabs on ~-racle will provide a ~ rnall a►zlol.►nt or herviotts _iika +inderneath. the foundation f.or w ►ter absvrhtiorr. if a full ba; ernent is I)oilt, will this rnpact. the tlrainaore in a significairt en0x►11h manner to regi►ire additional ,:Irainaae ne,:tsttres ;rot: specified in Chapter 18? 3. Underground structures in the 100 year floodplain are strictly controlled. Should there be additional regulatory language controlling the basements outside the 100 year floodplain?(BSC) is rcirt~t;rl portion" of strtlct►.►res locatcd in the 100 v' ar rloc'dplain tivhich ,.Ire below the ~e 110od Cie,, ~atic~n are taut allowcd unless they' ntcet criteria establislr;d in Section R-, - =u fflil:►r re<~t,faztit?Irs for str►ICttucs ~-Utside the flordplairt. 4. Should there be additional engineering criteria for the foundations of underground structures? (BSC) 6 • • ~,O(?l ndl (t.', of the (~i?cae' ilf (~rdin:al7Ci> i.icals '.~1t11 dic. Fcchnical Codes .Ind arlle'ndrnent5 to those codes. West U has arnetidrncnrs dealirn; A ith requirernc.nts for diff~retlt types of foundatioris. BaNernent walls :.Ire; riot iddres,,ed in this arnendrnent. SCCtiorl R403 of the _003 IRC, ;iddres~es sonle aspects of !rase Talent coii,.,trtlCtlon. DLit does not address aroximity to adjacent sites, depth of c.:cavation. ctc. 5. Should the area included within the walls of an underground structure be counted toward framed area? (ZPC) Framcd area defia)itiun ill Article 2 of the Zoning: Regulations 1.1sts bascinen.ts of a certain ,lC pth and less than' ceiling hci ,,ht as an ezerzaption to inclusion in the friimed area calculations. 6. Should the area included between the floor and ceiling of an underground structure be counted as a story? (ZPC) I'he current definition of a :story in the zoning rcvrulations I.vcnrld include the basement as a story for compliance with the story rule. if certain ba.senraems do not COLint toward trained ,area, tlaen should they be counted as a .,tore? Or if We Count the basement area as a story. should it he counted toward the maYinuim allowable framed area.' 7. What types of uses of an underground structure will be allowed? (ZPC or BSC) iiy eiiclosl.rre located below base flood elevation is limited. to parkin~o. ilccess to the ,ini.ciuxe. and t(,)r,ag . lVo could liinit a brrsenieiit to these u. e;s onl y _irld riot allow any .tlbitahle areas rrl a h:ascrnc;rrt.