Levin Roof Replacement

The purpose of this project is to replace the roof at the Theodore Levin U.S. Courthouse in Detroit, MI. The scope of work includes but not limited to: The scope of work for this project will include removing the existing ballasted built-up-roof (BUR), and underlying insulation, installing new insulation and fiberglass coverboard, and covering with a new gray PVC membrane. A portion of the roof in the light well was replaced with a new gray PVC roof in 2019 as part of the Prospectus stair tower construction. For purposes of this summary, the following streets surrounding the building are associated with these cardinal point directions: North – Lafayette; South – Fort Street; East – Shelby; and West – Washington. The roof levels are described by the floor level that they align with. For example, the roof covering the 2nd Floor is described as the 3rd Floor level. On the 3rd Floor level, the roof will be replaced on the west side of the building. A new stair tower is under construction (near completion) on the east side. New white PVC roofing and insulation on east side of the building has been installed. On the 4th Floor level, the roof will be replaced in the center section that bisects the 3rd Floor roof. On the 11th Floor level, the roof will be replaced on all sides. This floor has the most equipment, vents and other penetrations when compared to other floors. On the 13th Floor level (12th Floor roof) south penthouse, the roof will be replaced. On the 13th Floor level (12th Floor roof) north penthouse, the roof will be replaced. The total roof square footage is 52,203. The respective square footage areas per floor are as follows: § 3rd: 7,629 sf § 4th: 5,007 sf § 11th: 33,597 sf § 13th: 5,970 sf The Scope of Work is also noted to include the following: Removal of existing built-up roofing system with additional ballast and replacement with a new PVC roof membrane and lightweight insulation roofing system. Existing flashing will also be removed and replaced with new galvanized metal flashing similar to the existing. Tuckpointing and other treatments to the walls on which the roof is terminated that are not specifically required for a proper installation of the new roof are beyond the scope of work for this project. New metal stairs to recently installed penthouse on the east and west sides of the building. The existing stairs are constructed of pressure-treated lumber intended to be used on a temporary basis. GSA has obtained the new metal stairs under Prospectus that will be installed in this contract. A ladder is required on the west side of the 4th floor roof level so that the west roof level can be accessed without going into a tenant space and out of a window. The south and north two-story limestone penthouses have two ladders mounted to it although the same roof area is accessed by both. We have shown one ladder on each penthouse to be removed as one fewer element to degrade and impact the limestone facade over time. Removal of abandoned or obsolete roof-mounted equipment as identified by the GSA. Removal of abandoned PVC conduit mounted to the parapet walls. (The conduit mounted above the existing flashing is active and shall remain.) The roof shall be based on a 20-year warranty rated for up to 80 mph wind gusts. There shall be a hail warranty for 1” hail. Per ASHRAE 90.1-2019, buildings in the Climate Zone for this area (Climate Zone 5) must have insulation with a minimum R-Value of 30 for continuous insulation. Refer to excerpt below from the AE: • To achieve a minimum of R-30, I am proposing polyisocyanurate rigid insulation board at a thickness of 5” with a 1” cover board. The new roofing installed on the 3rd Floor level roof only had a thickness of 4.5” and it’s unclear how that was arrived at as the proper thickness. The lightweight concrete topping does have insulating properties, but it would need to be at least 5” thick to achieve the required R value with 4.5” of insulation. Here are the various: R values of the components used: 1” cover board R-0.67; Polyiso 4.5” R-26.8; Polyiso 5” R-29.6; 50 PCF lightweight: 5” R-3.65 and 2” R-1.46 The hazardous materials report includes roof core samples. This report was prepared by Castle Hill Associates, LLC and dated April 10, 2019. All of the samples came back negative for asbestos. Dual Outlet Overflow Drains narrative from AE: Because of the nature of the building (height and historic significance in particular), adding secondary overflow drains as are installed on new buildings is unrealistic to install here. Our solution for helping alert GSA to significant ponding on the roof is to install a dual outlet drain. We planning to place one in each quadrant of the 11th Floor. We felt that the 3rd and 4th Floors are readily visible and therefore not necessary. We have not added them to each of the two 13th Floor roofs despite the parapet walls exceeding 6 inches tall. The documentation from Prospectus shows that the roof can accommodate up to 6 inches of standing water. Our overflow drain would only be about 4 inches above the roof deck. We would include an alarm device in the vertical portion of the drain (in case there is a temporary backup in the horizontal portion of the drain pipe that gives a false reading) and connect back into the main drain lead for that sump.

Division 07 -

Thermal and Moisture Protection, Dampproofing and Waterproofing, Thermal Protection.