Flat Roofing

What a flat roof system assessment actually checks

Before anyone prices the job, we walk the rooftop and look at the parts that fail first. On a low-slope building, the leak you see inside is rarely where the water got in.

• Membrane condition: a TPO or EPDM sheet that has chalked, blistered, or delaminated is showing end-of-life wear, and a coating only buys time.
• Ponding water: low spots that stay wet a full day after a monsoon point to a drain, scupper, or slope problem rather than a hole in the membrane.
• Roof deck and substrate: soft spots underfoot mean the plywood or OSB sheathing has taken on moisture, and new membrane over wet decking hides decay.
• Flashing: step flashing at a wall, counter-flashing into masonry, and pipe boot or vent boot details at stacks are where most low-slope leaks begin.
• Parapet and coping: cracks in the parapet let water wick sideways into the wall, and loose coping metal lets it behind the membrane edge.
• Insulation and vapor barrier: saturated insulation loses R-value and has to come out, because it will not dry in place in this climate.

Membrane and material options, and why we pick one over another

• TPO single-ply is the workhorse on Phoenix commercial rooftops: it reflects heat, welds into one continuous sheet, and tolerates daily thermal cycling.
• EPDM rubber handles UV well and stays flexible, so it fits buildings where glare or heavy foot traffic is a consideration.
• PVC membrane resists grease and chemical exhaust, which is why we specify it over restaurant kitchens and loading docks.
• Modified bitumen is an asphalt-based reinforced sheet, and it is a strong recover option when the existing substrate is dry and sound.
• Built-up roof, or BUR, is the old tar-and-gravel assembly still sitting on plenty of older commercial buildings; we tear it off or overlay it based on what is below.
• A roof coating is a maintenance product; it only makes sense when the membrane underneath is intact.
• Insulation board and cover board set the R-value and shield it from hail and foot traffic, and denser board costs more and lasts longer.
• Adhesive and self-adhered sheets let us build a fully adhered assembly without driving fasteners through the field.
• Carlisle SynTec, Firestone, GAF EverGuard, and Versico publish system warranties in the 15 to 30 year NDL range when the whole assembly is theirs.

Why Phoenix is hard on a flat roof

Phoenix averages about 111 days a year at or above 100 F, and the rooftop surface runs hotter than the air. Heat oxidizes bitumen and dries out underlayment until it cracks.

Sunlight does the rest. Sustained UV photo-degrades elastomeric coatings and membranes until they flake and peel, so we check dry film thickness on a coating job instead of trusting the label.

Monsoon storms bring hail and wind uplift. The 2025 season damaged more than 500 homes in Tempe alone with hail, and flat roofs catch it across the field, where a bruise becomes a leak months later.

You will not find an ice dam or steam ice problem in Maricopa County, and there is no ice dam removal season here. Water sits, soaks, and erodes instead of freezing.

How the work runs, start to finish

1. Tear-off or recover: we strip old layers to the deck when the substrate is wet, and recover when it is dry and fastens down tight.
2. Deck repair: rotted plywood or OSB sheathing is cut out, and we check rafters, trusses, and joists while the roof deck is open.
3. Insulation and cover board: new insulation goes over the vapor barrier, then a cover board fastened with screws and plates sized to the local building code and wind uplift rating.
4. Membrane install: TPO is heat-welded, EPDM is bonded with adhesive and rollers, and modified bitumen goes down in staggered courses with a torch.
5. Flashing details: drip edge, parapet terminations, apron flashing, and boot flashing are set and hand-sealed with mastic or roof cement.
6. Final inspection: we flood-test the drain, walk the roofline, and haul debris and the dumpster off site the same week.

• Tools on the rooftop: a roofing square for layout, a nail gun or air compressor for fastening, a pry bar and roofing shovel for tear-off, plus ladder, scaffold, and safety harness rigging for access.
• Cleanup: debris leaves in the dumpster the same day, and we sweep for nails around driveways and parking lots before we go.

Timelines, cost drivers, and keeping a roof alive

A recover on a 5,000-square-foot rooftop usually runs two to three days. A full tear-off with new insulation and corrected drainage runs one to three weeks, depending on inspections and weather.

Price moves with membrane thickness, insulation R-value, how much deck repair turns up, and how many penetrations the parapets and curbs create. We quote by the square and itemize every line.

• Clear leaves and gravel from drains before monsoon season, because a blocked drain turns a small pond into a structural load.
• Check sealant and caulk at curbs, parapet caps, and pipe boots once a year; most of what we mend started as a hairline crack.
• Walk the rooftop after hail, since a bruised membrane or dented metal panel will not leak until months later.
• Ask about an attic fan or powered vent if the interior stays hot, and have a roof inspection done before you buy a building.

We will also tell you when a repair is enough and when the roof does not need to come off yet. Call 602-533-0488 for a free roof estimate.