Project Type: Evaluation, Design, and Construction Administration
The Vital Structure:
Office Park Building Roof Replacement
Issue
Vital Structures was retained to provide engineering services for the partial replacement of the roof system of one (1) wing of the building, as well as the upper atrium roof at an office building insured by FM Global. The facilities manager also reported to Vital Structures that the brick masonry rising walls above the Atrium were a source of leaks. Vital Structures also noted that the metal panel siding around the Atrium walls (above the main roof) were poorly secured to the back-up wall structure.
Diagnosis
The main roof single-ply PVC membrane was due for replacement, due to general age, wear and loss of plasticizer. The existing single-ply EPDM roof system on the Atrium Roof was due for replacement due to general age and wear. Both roofs had no consistent slope towards the internal roof drains and as a result ponding water was common on each roof. Vital Structures evaluation also noted the following concerns:
- Brick masonry through-wall flashings with no end-dams at termination points, allowing moisture to enter into the atrium below.
- Low flashing heights at brick masonry walls, fall protection roof anchors, mechanical units and skylights, necessitating modifications of each in order to replace the roof system and meet slope-to-drain and insulation code requirements.
- Hazardous materials analysis found that asbestos-containing mastics and built-up-roofing were present below both roof systems.
- Damaged roof drain components.
- Substantial ponding water between two (2) skylights with poor slope-to-drain conditions.
Solution
Vital Structures performed an evaluation with programmatic leak testing, destructive test cuts of roofing and masonry, and prepared design documents with the following scope:
- Roof replacement with R-30 roof assembly, improved slope-to-drain, and induction-welded KEE single-ply roof system.
- New through-wall flashings at brick masonry rising walls.
- Infill of abandoned louver opening in brick masonry rising walls.
- New FM-approved engineered coping caps.
- Replaced existing overflow through-wall scuppers with new zinc-coated copper through-wall scuppers, scupper boxes and downspouts at Atrium Roof.
- New metal wall panels supported on furring high-hat channels.
- Removed abandoned rooftop mechanical equipment and skylights.
- Design document review and final field review were approved by FM Global.
