Project Type: Evaluation, Design, Bid & Limited Construction Administration
McLaughlin Middle School, Manchester, NH – Steep Slope Roof Replacement
Issue
Vital Structures was retained to perform an evaluation of the existing standing seam metal and EPDM (rubber) roofs of the East and South Classroom buildings. The facilities manager specifically noted that the metal and EPDM roofs were failing, and leaks were occurring in the classroom spaces below the roofs.
Existing Deficient Metal and EPDM Roof Systems with Failed adhered Snow Guards.
Minimal/Insufficient Transitional Lap Detail of EPDM Roof and Metal Roof Underlayment Over Unprotected Wood Roof Deck.
Coating Failure and Corrosion at Existing
Diagnosis
There were several areas of concern with the existing roof systems including the questionable transitional areas between the metal and EPDM roofs, and general snow and ice management deficiencies causing damage to the EPDM membrane roof systems. Vital Structures performed an evaluation of the existing metal panel and EPDM roof systems; including a review of original design documents, exploratory test cuts, and a comprehensive evaluation of the roof systems including the roof venting, insulation, and roof deck substrates. The following conditions were noted by Vital Structures:
- Poor/insufficient transitional detailing between the EPDM and metal panel roofs leading to suspected roof leaks.
- Absence of a thermal barrier board at the wood roof deck.
- Damage to EPDM roofs from snow and ice impact (at dormer roofs missing snow guards) and build-up in EPDM strip roofs with numerous remedial membrane repairs.
- Questionable areas of slope to the internal drains at the EPDM perimeter strip roofs with standing water under the roof membrane in some locations.
- Active roof leaks to the interior classroom spaces.
- Failed adhered, pad style snow guards and non-engineered 2-rail snow guards added to steep slope metal panel roof system.
- Un-sealed HVAC systems under negative pressure.
- Roof membrane punctures and insufficient slope-to-drain due to saturating and crushing of the roof assembly.
Our Solution
Vital Structures prepared a roof evaluation report with evaluation findings, analysis of IEBC-2015 re-roofing analysis and provisions, general recommendations, and options for the roof system(s) replacement. Vital Structures was also tasked with the new roofing systems design, bid assistance and limited construction administration for the buildings. The evaluation report and design included the following:
- The addition of plywood crickets to address and eliminate areas of insufficient slope-to-drain conditions.
- Full roof removal and replacement including refastening questionable plywood roof deck and installation of new mechanically fastened 5/8-inch, fire resistant, thermal barrier board over the existing plywood roof deck.
- Installation of a more durable felt backed, adhered PVC roof membrane with monolithic heat-welded seams and decorative ribs in matching color/profile to the existing metal roof system.
- Installation of a proprietary tab-style roof snow guard system designed to meet the existing roof structural capacities for snow loads.
- Design and installation of new, custom-designed and fabricated continuous PVC-coated metal ridge vents (in matching membrane colors) at the ridge and hip vent locations of the new roofs.
- Removal and replacement of emergency roof overflow through-wall scuppers.
- Internal roof drain rehabilitation.
- Various low slope roof upgrades and repairs at adjacent roof areas to East and South Classroom buildings.
Installation of a New Fire-Resistant Thermal Barrier Board Over Existing Plywood Roof Deck.
New Custom Designed and Fabricated New Continuous Roof Ridge Vent and PVC Membrane Roof
New PVC Membrane Roof with PVC Decorative Ribs and Tab-Style Snow Guards.
Result
The results of the in-depth roof evaluation provided invaluable knowledge of the existing roof system deficiencies for the appropriate recommendations for the new roof system and accessories to resolve the interior leak problems and other design challenges for the roof system improvements including:
- Added crickets for more effective, improved slope-to-drain.
- The addition of a fire-resistant thermal barrier board over the existing wood roof deck.
- A new, more durable, monolithic PVC membrane roof system to address snow and ice conditions while meeting aesthetic requirements for the steep slope roofs.
- New continuous roof venting accessories to provide required venting and aesthetic needs.
- A new roof snow guard system that conformed to the existing roof framing structural capacities.
The result provided the Client with new, durable, and effectively functioning roofing systems for the buildings with 20-year manufacturer’s warranties that resolved their project issues and challenges.
