WS 05-04-2009 - Laserfiche WebLink

Home Browse Search

;7 • • BKBM � 'D 5930 a Brooklyn N ulevard 55429 - Minneapolis, MN 55429-2518 (763) 843-0420 Fax: (763) 843-0421 www.bkbm.com April 16, 2009 Mr. John Skraba Inspec, Inc. 5801 Duluth Street Minneapolis, MN 55422 Re: New Brighton Family Service Center Roof Evaluation BKBM Project No. 09256.00 Dear John: As requested, BKBM Engineers has performed a ponding stability analysis of the existing roof structure of the Family Service Center in New Brighton, MN, as outlined in our February 2, 2009 proposal. Ponding is the retention of water on relatively flat roofs as the members deflect under load. The purpose of our analysis was to help you determine options for roof repair or replacement due to ponded water and leakage that the City of New Brighton has experienced. Our analysis was based on the member sizes and layout shown on the existing building drawings by BKBM, dated February 1, 1994. The existing flat roof structure consists of steel bar joists and metal roof deck on the west half of the roof and precast concrete plank on the east half of the roof. The existing documents indicate the structure was designed using a 25 psf superimposed dead load and a 40 psf superimposed live load, plus drifting snow in accordance with the prevailing MN State Building Code in effect at the time of design. The 2006 International Building Code requires a 1/4 inch per foot minimum roof slope to avoid a ponding stability analysis. According to the original roof plan prepared by Williams/O'Brien Associates, Inc., the roofing system was placed with a slope less than 1/4 inch per foot. We performed a ponding analysis of typical roof framing conditions and it is our opinion the structure has adequate stiffness to remain stable under ponded water loads. The opinions and recommendations contained in this letter report are based on the information provided in the 1994 building drawings and our design check calculations based on those drawings. No visit to the site was made. This report does not address any portions of the existing structure other than the members mentioned, nor does it provide any warranty, either expressed or implied, for any portion of the existing structure. We appreciate the opportunity to assist you with this project. If you have any questions, please contact me. This report was prepared by me or under my direct supervision and I am a duly licensed Professional Engineer under the laws of the State of Minnesota. Sincerely, BKBM ENGINEERS ,nQ,Gzcc.�c� Tina A. Wyffels, P.E. MN License Number 42758 F:\09\09256\ConvapandenceVLetmNSkraba 04-16-09AGe BKSM ENGINEERS An Equal Opportunity Employer Direct Line: (763) 843-0436