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HomeMy WebLinkAbout10152009 BSC Agenda Item 5 Joint Preliminary Report Zoning and Planning Commission (ZPC) & Building and Standards Commission (BSC) September 22, 2008 Sub ct Basements/Underground Structures Background Recently, City Planner, Debbie Scarcella, alerted the ZPC and BSC to the fact that builders in WestUniversity Place are beginning to include subterranean structures (basements) in their projects. (See Attachment "A"). 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 Attachment "B" 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 Attachment "A" EXCAVATIONS AND UNDERGROUND STRUCTURES June 9, 2008 The key issues regarding excavations and underground structures are as follows: 1. A. Should the underground structure project into the yards and if so, then how much? Should the excavation area be allowed to project into the yards? (ZPC) Table 7-6 of the Zoning Regulations lists those items allowed to project into the regulated yards. Underground items are not restricted at all as to the limits of their encroachment into these yards. Conceivably, a basement would technically be allowed to span. the entire building site from property line to property line unrestricted. B. Should underground structures be allowed on narrow lots taking the 3/7 alternate side yard exception? Narrow lots (Less than 55' wide) are given an option to use alternate side yards. This is allowed to encourage rear situated garages. If a structure built underground on a narrow site is constructed when taking the alternate side setback allowance, should there be limits and restrictions on the proximity of the basement wall. and the excavation to adjoining property lines. 2. If an underground structure is allowed in the yard areas, should there be special rules for lot drainage regulations? (BSC) Chapter 1.8 provides regulations for building site drainage and controlling the runoff rate based on a 1" per hour rainfall. Slabs on grade will provide a small amount of pervious area underneath the foundation for water absorption. If a full basement is built, will this impact the drainage in a significant enough manner to require additional drainage measures not 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) Enclosed portions of structures located in the 1.00 year floodplain which. are below the base flood elevation are not allowed unless they meet criteria established in Section R323 of the 2003 IRC and Chapter 18 Article IX of the city's Code of Ordinances. There are no similar regulations for structures outside the floodplain. Attachment "A" 4. Should there be additional engineering criteria for the foundations of underground structures? (BSC) Appendix C of the Code of Ordinances deals with the Technical Codes and amendments to those codes. West U has amendments dealing with requirements for different types of foundations. Basement walls are not addressed in this amendment. Section R403 of the 2003 IRC addresses some aspects of basement construction, but does not address proximity to adjacent sites, depth of excavation, etc. 5. Should the area included within the walls of an underground structure be counted toward framed area? (ZPC) Framed area definition in Article 2 of the Zoning Regulations lists basements of a certain depth and less than 8' ceiling height as an exemption to inclusion in the framed area calculations. 6. Should the area included between the floor and ceiling of an underground structure be counted as a story? (ZPC) The current definition of a story in the zoning regulations would include the basement as a story for compliance with the 2-%z story rule. If certain basements do not count toward framed area, then should they be counted as a story? Or if we count the basement area as a story, should it be counted toward the maximum allowable framed area? 7. What types of uses of an underground structure will be allowed? (ZPC or BSC) Any enclosure located below base flood elevation is limited to parking, access to the structure, and storage. We could limit a basement to these uses only and not allow any habitable areas in a basement. Attachment "B" List of Concepts and Guidelines Excavations and Underground Structures September 22, 2008 At the meeting on July 10, 2008, the Zoning and Planning Commission compiled 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 swimming pool construction rules and flood regulations 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} rZoning 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 7-6] 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 in proportion to the footprint of the floor above {ZPC} [Article II Definitions-either definition of basement or half-story] H. Restrict uses and occupancies (storage, elevators, and non-sleeping and non-habitable areas 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] Attachment "B" 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 prohibit basements in Special Flood Hazard Areas (Zone AE, 100 year floodplain)] 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] Regulation of basements and other "below-grade spaces" 7-09-09 ZPC Position forward to BSC Issue ZPC Consensus BSC Consensus Definition of "below Defer to definition of BSC agrees grade space" basement in the IRC Size limit No limit Under footprint of house only Counts as framed area No Yes, if use and size limit changes over 200 Sq. Ft. Counts as a story No Defer to the IRC Height limit None None Plumbing fixtures Allowed per plumbing Depends on if use (does not apply to code requirements changes lines) Use restriction None Storage or mechanical equipment only if greater than 200 Sq. Ft. Number of emergency Defer to the IRC Defer to the IRC egress paths (EEP's) EEP directly to Defer to the IRC Defer to the IRC outdoors Indoor swimming pool Not in ZPC purview No in below grade space Excavation limits No projection or Refer to staff - depth of (ratio of distance from encroachment into the excavation will be property line to depth regulated yards equal to the distance of hole) (setbacks) allowed at from the property line; any time during 45 degrees depth construction or at finished product. Location in "footprint" No encroachment into Under footprint of house of principal building any regulated yards only (below other building (setbacks): 3/7 space) alternated side yard setback (narrow lots) will not be allowed with basement construction. Synopsis of the Building & Standards Commission Meeting September 3, 2009 The subjects of the meeting are as follows: 1. Notices. Rules. Etc. Matters relating to notices, introductions, rules, meeting procedures and identifying parties. 2. Regular members in attendance: Chairman Bryant Slimp, Gerry Spedale, The alternate voting members were as follows: Frank Griffin, Dave Miller 3. Regular members not in attendance: and Peter Benjamin, Dave Flame, Brian Hoogendam, J. Denis Powers. 4. Meetine Minutes. Matters relating to discussion and approval of the meeting minutes of August 6, 2009 and August 20, 2009. Both were approved with changes. 5. Docket Number 2009-03 reearding property at 5410 Kirby. West University Place. Texas 77005 (Variance) No one was in attendance and Mr. Dave McMahan was notified via fax with a n recem . Basements and other subterranean structures including ordinance amendments, updates and related matters. Mr. David Eastwood, PE, Mr. Robert Cunningham, PE and Mr. Lynn Ratcliff, PE all spoke on the subject of basements. Do's and Don'ts: Do's: • Require them to have a minimum of a 12 inch cast-in-place reinforced concrete foundation wall. • Require them to have a standby generator. • Require them to be provided with a sump pump system. • Require an exterior drainage system. • Require water proofing on the exterior of the basement wall. • Require any shoring to be designed by a registered professional engineer. • Require a 2:1 ratio of distance to side property line to depth of excavation or install engineered soldier pilings (not driven but drilled) to protect adjacent property. Don'ts • Don't allow foundation walls to be constructed using concrete masonry units (CMU'S) Consensus of all three engineers was basements can be designed to structurally function however they don't recommend them being allowed in West University Place. October I' meeting was moved to cto er , [Adjournment.]