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Freiheit & Ho letter date 4-17-07.pdfH E I T& H 0 RECEIVED ARC=IIITECTS INC. P.S. 30230 NE.`POINTS ©RIVE SUITE 304 KIRKLAND, WA 9803 MAY 3 2007 P:425 82:7 2700'.F 42:828.6899 wWW.FHOARCH.COM PERMIT COUNTER April 17, 2007 CITY OF EDMONDS BUILDING DIVISION 121 FIFTH AVENUE NORTH EDMONDS, WASHINGTON 98020 ATTN: ANN BULLIS RE: STEVENS HEALTH CENTER — INTERIOR REMODEL (CORRIDORS) REQUEST FOR ALTERNATE METHOD OF DESIGN PROJECT ADDRESS: 21701 -761" AVENUE WEST CITY PLAN CHECK #2006.1088 Ms. Bullis: Thank you for taking the time to meet with us to discuss the recently discovered HVAC installation as it relates to the one-hour corridor construction at the Stevens Health Center Building. In response to this meeting, and because of the situation of the non -ducted return air relative to the HVAC installation within the one-hour corridors, we understand that it will be necessary to request an alternate method of materials, design, construction or equipment, as allowed under Section 104.11 of the 2003 IBC. As such, please find following, the background, reasoning, and methodology used to support our request for an alternate design for the HVAC installation in the common area, one-hour rated corridors. Background: 1. The HVAC system (using the area above the lay -in acoustical ceiling as both a supply and return air system) was installed as a part of the original building construction (about 1985) and was further enlarged as a part of the building expansion (about 1989). The HVAC heat pump units were initially installed in the plenum spaces above the tenant areas, in the corridors, and directly above the corridor walls (most one- hour corridor walls were not extended up to the one-hour floor ceiling assembly above). The entire ceiling space above the lay -in acoustical ceiling (both in the tenant spaces and in the one-hour rated corridors) was designed and used as one, large, return air plenum. 2. It was recognized by all parties (City and Owner) that the use of continuous return air plenums across the one-hour rated corridors was not in conformance with the intent (or for that matter even the specific language) of the Building Code(s) under which the building was originally built and then enlarged. 3. As such, the City has required (as an extension of HVAC repair work that was occurring within the building) that the corridors be brought up to current one-hour corridor standards. Amongst other things, this work r A05397-4.doc Stevens Health Center Request for Alternate Design April 17, 2007 includes the extension of the rated walls that compose the one-hour rated corridors upward to the underside of the one-hour floor ceiling assembly, the installation of 20 minute rated doors and frames, the installation of all appropriate door hardware, the installation new 45 minute rated frames and glazing for all relites, the installation of smoke protection in front all elevator door openings, the fire caulking of all conduit and piping penetrations, and the installation of new fire/smoke dampers across all HVAC openings between the one-hour rated corridor and the tenant spaces. Also required is the connection of all roll down smoke and fire doors and all HVAC fire/smoke dampers to both the building fire alarm system and localized smoke detectors. 4. Permits (Building, HVAC, Electrical, Fire Alarm) were issued for the common area, one-hour corridor construction on all three floors of the Stevens Health Center building. These permits were issued with the intent of bringing the existing corridors up to 2003 IBC one-hour corridor standards. 5. The construction of the work shown on the issued permits is currently underway. The walls, doors, relites, and other architectural features are approximately 50% complete, the HVAC work is approximately 85% complete, and the fire alarm system is approximately 90% complete. 6. As a part of the work under the current permits, some of the existing HVAC heat pump units have been moved to allow the existing one-hour rated corridor walls to be extended upward to the bottom of the one- hour floor ceiling assembly and thus provide true one-hour corridor protection. Because of restricted clearances some of these relocated units were moved to the tenant side of the one-hour rated corridor walls and others were relocated to the corridor side of the one-hour rated corridor walls. Other units were already entirely within the one-hour rated corridors and remained where they were originally located. 7. We understand that the primary objection to the current construction is the non -ducted return air ducts for the HVAC heat pump units that were relocated (or remained) above the lay -in acoustical ceilings within the one-hour rated corridors but that service the adjacent tenant space. These non -ducted return air systems are effectively using the area above the lay -in acoustical ceiling in the one-hour corridor as a return air plenum that serves not the corridor (which would be allowed), but the adjacent tenant areas (which is not allowed). Per section 1016.4 of the IBC, the use of a ceiling area in a rated corridor as a return air plenum for adjacent areas is specifically not allowed. Proposal As the City has identified, the logical and obvious solution to the problem described in item 7 above is to simply duct the return air from the above ceiling corridor mounted heat pump units and to provide fire/smoke dampers where these ducts penetrate the one-hour corridor walls. We agree that the ducting and fire/smoke dampering of the return air duct would solve the issue, but this is not technically feasible. Because of the limited vertical distance between the existing lay -in acoustical ceiling in the one-hour corridor and the bottom of the one-hour floor ceiling assembly above, and because of the number of conflicting items in the plenum space above the corridor ceiling (electrical and low voltage conduit, HVAC water lines, domestic water lines, ceiling support wires, and light fixtures) there simply is not enough room in the plenum area to accommodate all the other necessary existing systems and any new return air ducting. As all of the other systems are in place and operational, and the heat pump return air ducting is not, the heat pump return air ducting needs an alternate solution. A05397-4.doc Stevens Health Center Request for Alternate Design April 17, 2007 As such, we are requesting that the City review the following design proposal and the attached supporting letters, charts, plans and details relative to providing appropriate altemate occupant protection within the one-hour rated corridors, and provide approval of this alternate design as allowed under Section 104 of 2003 IBC. 1. Please see attached, an architectural sketch of the proposed solution. This sketch provides a basic understanding of the existing situation. The primary item to take from this sketch is to note that the various elements of the corridor construction work together to provide complete and total protection to the occupants of the building. 2. Please see the attached letter from ABSCO dated April 16, 2007. This letter, its referenced Output Activation chart (11x17), and the attached fire alarm system drawings, describe in detail, the proposed fire protection systems that will coordinate the activities of the HVAC system heat pumps, the fire/smoke dampers, and various roll down doors and fire curtains during a fire or smoke generation event in which a pull station, smoke detector or duct detector are activated. We believe that the described system provides a reasonable and safe response to a fire or smoke event within the building and that these proposed systems are well over and above the code required minimums. 3. The City has stated that there is some concern regarding the potential for a fire (and thus some smoke generation) within the heat pump units themselves. This is a valid concern. However, please note that heat pump units of this type have very few moving parts and the likelihood of a fire within the unit itself is extremely small. Additionally, even if there were a fire within the heat pump unit, the volume of combustible material is minimal. There is a small amount of paper surrounding the air filter at each unit. This paper is equivalent to about three sheets of S 112 x 11 paper. Additionally, there is some plastic jacket insulation surrounding some of the control wiring. There is approximately 2 feet of total wiring length. The conclusion to this concern about fire and smoke generated from a heat pump fire is that the units themselves are very reliable and there is very little that can bum and in tum, produce smoke. Thus, this issue should have little bearing on our request. In conclusion, we believe that the propose design using fire/smoke dampers connected to both localized (but with full floor by floor activation) smoke detectors and to the floor by floor activated pull stations, to close off any path of return air smoke from the tenant spaces to the heat pumps (or vise versa) meets the full intent of maintaining a completely sealed one-hour corridor environment. Thus our proposal is in keeping with the intent of the IBC. Specifically, IBC Commentary Volume 1, Section 1016.1, Corridors, under the first sentence of the interpretation states, "The purpose of corridor enclosures is to provide fire protection to occupants as they travel the confined path." Based upon our conversations, we believe that the City also agrees with this statement. As we are proposing to protect the corridor occupants in a manner that is consistent with this very idea, we would request that the City review our proposal and, as allowed under Section 104.11 of the IBC, find that the currently permitted HVAC system design with all its firelsmoke dampers, along with the described fire alarm control system, be considered as providing appropriate and equivalent occupant protection within the one-hour rated corridors. Please note that we have not forwarded a copy of this letter to either Jeannine Graf in your office or to Mike Smith in the Fire Marshal's office. We do not wish to inconvenience them and we anticipate that your office, as you deem necessary, will coordinate. a review of this request with them. A05347-4.doc Stevens Health Center Request for Alternate Design April 17, 2007 Thank you again for your time and effort. Please do not hesitate to contact us if you have any questions or require any additional information. Sincerely, FREIHEIT & HO ARCHITECTS, INC., P.S. R. &RIME5 Rick Grimes, AIA, CSI Principal Attachments: Architectural section at one-hour corridor ABSCO narrative of fire alarm modifications dated 4.16.07 ABSCO drawings dated 4.11.07 Cc: Rosen Harbottle, Vicki McDermott ACCO, Tim Garoutte ACCO, Danny Dalum ABSCO, Dan Norton Davis Schueller, Jim Stockberger A05397-4.dac sss� Rt (7lT CK VATEOMr; i€iG'u�3