2300 KASCH PARK RD 2020-12-31 - Laserfiche WebLink

• Response: KPFF Comments: Our 10/09/2018 report does not indicate that the roof construction and connections are deficient. At the end of our report,we note that due to the age of the building that certain components likely do not meet current seismic code-level design forces. b. City of Everett Comment:The report states the same 1.3 lbs allowance for both the gravity and seismic weight increase. However,the threshold for performing gravity and seismic analyses is different—5%vs 10%, respectively. Response: KPFF Comments: Our 10/09/2018 report indicates that the added roof system weight is anticipated to be no greater than 1.3 lb. Including snow loads,the gravity load increase will be less than 5%. The seismic load (resulting from dead load) increase will be less than 10%. Based on that reasoning,5%/10%thresholds are met. c. City of Everett Comment: It is presumed that this project will qualify as a Level 1 Alternation per IEBC Chapter 7. Per Section 707.2 Exception 3, up to 3 psf of additional roof load is acceptable without meeting current code. The designer-of-record (DOR) should determine if Chapter 7 is the governing criteria proposed for the project, and verify if the design meets and is acceptable per Exception 3. Note also Exception 1 for the 5%gravity load. Also note that this section does not include a requirement to check seismic loading. Response: KPFF Comments:As described,the added roof system weight will be no greater than 1.3 psf, less than the 3 psf noted above. Including snow loads,the gravity load increase will be less than 5% for all elements. Wetherholt Comments: The specified roofing materials and weights are as follows: • Single ply membrane: Basis of Design:Sika Sarnafil G410 60 mil PVC single ply:0.39 lbs/sq. ft. (Refer to attached product data sheet) • Coverboard: Basis of design: Hunter H-Shield HD (High Density Polyisocyanurate Coverboard):0.343 lbs/sq.ft. (Refer to attached product data sheet) • Insulation in the flutes: Expanded polystyrene(EPS): Minimal 4. City of Everett Comment:Sheets R3.01 and R9 show a new raised parapet around the perimeter of the roof. The following two comments shall be addressed: a. City of Everett Comment:The raised parapet creates a fundamental change in the performance of the roof for drainage. This could result in a ponding condition. The DOR should comment on the proposed portions of the IEBC governing this change. This may require analysis of the roof to support current code-level forces, including additional ponding loads per the SEAW White Paper on snow loads and ASCE 7-10 for low-slope roofs. Response: KPFF Comments:The parapet height will increase by—2.5",which is very small. In our opinion, this does not trigger the need to re-assess the snow load on the roof.