Engineering · Low-slope systems
Specified by assembly, not by brochure
Membrane gauge, coating thickness above the scrim, wind uplift, puncture resistance and chemical exposure — the numbers your engineer will ask for, published up front.
- FM 1-90 assemblies
- ASTM-tested gauges
- NDL warranty eligible
- Membrane gauges we install
- 45–80 milMembrane gauges we install
- CT energy code minimum on re-roofs
- R-30CT energy code minimum on re-roofs
- Target drainage after rainfall
- 48 hrsTarget drainage after rainfall
Anatomy
Inside a commercial roof assembly
Clickable assembly stack
Top to bottom, the five layers of a specified low-slope roof — and the inspection point that makes each one perform.
Select any layer to see what it does and what we inspect it for.
Inspection point
Heat-welded membrane
60 mil TPO / PVC · hot-air welded seams
The weatherproofing layer. Seams are robotically hot-air welded so the joint is stronger than the sheet itself — nothing is taped or glued in the field.
What we check
Every seam is probed with a hand tool, and daily weld test cuts are pulled and filed in the closeout package with the welder's temperature log.
Engineering spec
45 vs 60 vs 80 mil, side by side
| Engineering spec | |||
|---|---|---|---|
| Nominal thickness | 1.14 mm | 1.52 mm | 2.03 mm |
| Coating over scrim | ~15 mil above scrim | ~22 mil above scrim | ~32 mil above scrim |
| Solar Reflectance Index (white) | 104 initial / ~79 aged | 108 initial / ~83 aged | 110 initial / ~85 aged |
| Wind uplift rating (typical) | FM 1-60 typical | FM 1-90 achievable | FM 1-90 / 1-120 with enhancement |
| Static puncture resistance | ≈ 200 lbf (ASTM D5602) | ≈ 300 lbf (ASTM D5602) | ≈ 400 lbf (ASTM D5602) |
| Chemical exposure | Limited — no grease or solvent exposure | Good — PVC formulation for grease exhaust | Best — full grease, oil and process exhaust |
| NDL warranty available | 15 year | 20–25 year | 30 year NDL |
| Expected service life | 15–20 years | 20–25 years | 25–30+ years |
Where 60 mil belongs
The commercial standard and our default specification. The extra coating above the scrim is what buys the second decade of service life.
Values are typical published ranges for white thermoplastic membranes; the exact figures for your specified manufacturer are included in the submittal packet.
Membranes
Select a system
TPO
Heat-welded thermoplastic polyolefin — the volume choice for new commercial work.
- Typical service life
- 20–25 years
- Membrane thickness
- 45, 60 or 80 mil
- Seam technology
- Hot-air welded, stronger than the sheet
- Solar reflectance
- ~0.79 initial (white)
- Warranty
- 15–30 year NDL available
- Best fit
- Large, relatively simple roof fields
TPO's white reflective surface reduces rooftop surface temperature dramatically in summer, which lowers cooling load and slows membrane aging. On a large distribution roof that reflectivity is a measurable operating-cost line, not a marketing claim.
Because seams are hot-air welded rather than taped, weld quality is everything. We probe every seam and keep daily weld test cuts on file with the closeout package.
Next step
Submittal review or full RFP
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