Flat Roof Replacement – Clifton Garage Addition
Project Overview
A Clifton homeowner contacted us after noticing water stains spreading across the ceiling of their attached two-car garage following a series of late-summer storms. The garage had a low-slope flat roof over approximately 600 square feet, covered with an original EPDM rubber membrane that had never been replaced since the addition was built in the early 2000s. What started as what the homeowner thought would be a simple patch turned out to require a complete tear-off and replacement — the existing membrane was blistered, cracked at seams, and had been patched at least twice before with incompatible materials. The parapet wall flashing had pulled away entirely on the north side, and the roof drain was so clogged it had been allowing standing water to pond for years. Exterior Solutions LLC performed a complete tear-off down to the roof deck, replaced damaged decking, and installed a fully adhered TPO membrane system with new coping, drain, and flashing throughout.
Analysis
Once we stripped the existing EPDM membrane, we found two 4x8 sections of the OSB roof deck that were fully saturated and delaminating — they had to be cut out and replaced with new 5/8-inch CDX plywood, screwed and glued to the rafters. We also discovered that the original roof had been installed with inadequate slope — barely 1/8 inch per foot in the drain basin area, well below the minimum 1/4-inch-per-foot code requirement. To correct this we installed tapered polyiso insulation boards across the full deck, creating a proper positive slope from the parapet walls to the single interior drain. This also brought the R-value of the assembly up to current NJ energy code minimums for low-slope roofs. The parapet wall was inspected: the wood nailer at the top was rotted and had to be replaced before new coping could be installed.
Process
Tear-off began day one, with the old EPDM and adhesive debris loaded into a roll-off dumpster by midday. Deck replacement was completed that afternoon — plywood panels cut, glued, and screwed, left to cure overnight. Day two: tapered polyiso boards delivered and installed, starting from the drain and working outward, each board number marked to ensure correct taper sequence. Day three: TPO membrane installation began at the parapet base and worked toward center — bonding adhesive applied, membrane rolled out and embedded, seams lapped and heat-welded. Flashing terminations at parapet completed and heat-welded. Day four: coping cap installation and drain final set. Day five: full seam probe test, water test, final inspection, site cleanup, and dumpster pull.
Outcome
The homeowner had been chasing leaks in that garage ceiling for three years, patching drywall and ceiling tiles after each storm. The day after our water test confirmed the roof was watertight, they reported — for the first time in years — a dry ceiling after a heavy overnight rain. The new TPO membrane with tapered insulation and properly functioning drain has eliminated all standing water. The aluminum coping cap gives the parapet a clean, finished look visible from the street. The system carries a 15-year Firestone contractor warranty and a 10-year labor warranty from Exterior Solutions LLC.
Project Details
Materials Used
Tear-off and deck repair: 5/8-inch CDX plywood replacement panels, construction adhesive and #10 screws. Insulation: tapered polyiso insulation boards, 1/4 inch per foot slope, R-20 total assembly value, mechanically fastened at perimeter. Membrane: 60-mil TPO (Firestone UltraPly TPO), fully adhered with Firestone bonding adhesive over polyiso field, heat-welded seams at all laps, minimum 6-inch lap width. Flashing: 60-mil TPO membrane flashing at all penetrations and parapet walls, heat-welded. Coping: 24-gauge aluminum snap-lock coping cap, factory-painted white, continuous cleat anchored to new pressure-treated nailer. Drain: Zurn 4-inch cast iron roof drain with domed strainer and new clamping ring set into TPO membrane. Walkpad: TPO walkpad strips at access hatch approach. All seams probe-tested with 1-inch ball probe prior to sign-off.
Methods & Techniques
Full tear-off of existing EPDM membrane and insulation to bare roof deck. Deck inspection and replacement of two deteriorated 4x8 plywood sections. Tapered polyiso insulation installation — mechanically fastened perimeter, adhered field — creating 1/4-inch positive slope. TPO membrane fully adhered with roller application of bonding adhesive in both deck and membrane surfaces. Seams heat-welded with Leister hot-air welder, all welds probe-tested. Parapet wall flashing installed as TPO membrane turned up and heat-welded. New pressure-treated parapet nailer installed, new aluminum snap-lock coping cap installed over continuous cleat. Drain body set in TPO membrane, clamping ring tightened, dome strainer installed. Final inspection and water test with hose.
Key Highlights
Complete EPDM tear-off and TPO replacement on 600 sq ft low-slope garage roof. Two deteriorated roof deck sections replaced. Tapered polyiso insulation for positive drainage and R-20 insulation value. 60-mil Firestone UltraPly TPO fully adhered membrane with heat-welded seams. New cast iron drain with dome strainer. New aluminum snap-lock coping cap on rebuilt parapet. All seams probe-tested and water-test verified. 15-year Firestone membrane warranty.