Why carbon math starts at the bucket
Liquid membranes travel light—no rolls, no torch—but the polyols, isocyanates, and plasticizers inside them are anything but weightless. Cradle-to-gate CO₂ for a high-rise reroof can outrank a year of elevator electricity. That makes the membrane’s EPD a gatekeeper for low-embodied-carbon bids.
Meet three membrane archetypes
- Kemperol 2K-PUR – castor-oil–rich, solvent-free polyurethane (EPD-KEMPER, 2023).
- Sikalastic 644 Lo-VOC (Reemat system) – moisture-triggered aliphatic PU with glass reinforcement (EPD-115, 2019).
- Carlisle Sure-Flex KEE HP – PVC/KEE single-ply factory sheet, often liquid-flashed at seams (EPD-236, 2021).
Apples, oranges, kilograms
Kemper declares 1 kg of resin, Sika and Carlisle declare 1 m² of finished roof. To compare, you need a coverage rate. Industry applicators put Kemperol at ~2.5 kg ⁄ m² for a 2-mm build. We’ll use that as a bridge.
At Kemper, Sika, or Carlisle?
Follow us for a product-by-product EPD analysis to understand which membranes get spec'd and where carbon performance gaps could impact your bids.
Carbon scorecard (A1–A3 only)
| Membrane | Declared unit | GWP A1-A3 |
|---|---|---|
| Kemperol 2K-PUR | 1 kg | 1.8 kg CO₂e |
| Converted Kemper (≈2.5 kg ⁄ m²) | 1 m² | ≈4.5 kg CO₂e |
| Carlisle KEE HP 50 mil | 1 m² | 5.5 kg CO₂e (EPD-236, 2021) |
| Sikalastic 644 Reemat 84 mil | 1 m² | 14.4 kg CO₂e (EPD-115, 2019) |
The spread is stark: the heaviest Sika build more than triples Kemper’s converted footprint. Remember: thickness, reinforcement, and color options shift these numbers; always check the exact EPD line you’re specifying.
Durability: the overlooked denominator
A membrane that lasts twice as long can halve annualized carbon. Kemperol’s ETA pegs an expected service life of 25 years (ETA reference, 2024). Carlisle markets 30-year warranted assemblies, while Sika publishes 20- to 25-year system guides. Plug those spans into your life-cycle model before declaring a winner.
Don’t skip the fine print
- Modules covered. Carlisle’s sheet is cradle-to-gate; Sika’s is cradle-to-grave, so its number bakes in demolition fuels. Equalize scopes or risk mis-specifying.
- Biogenic carbon. Castor oil in Kemperol earns a small credit that some databases strip out. Verify whether GWP-total or GWP-fossil drives your rating system.
- Program operator quirks. ASTM EPDs list TRACI impacts, whereas IBU follows EN 15804+A2. Translating impact categories later is a headache—sort it now.
Data gathering without the migraine
Harvesting plant energy, resin recipes, and waste logs across three facilities can stall a new product launch for six months. A streamlined data-capture workflow (think pre-built templates, cloud pulls, and white-glove reminders) slashes that timeline so R&D can get back to formulating the next solvent-free resin. No one was hired to babysit spreadsheets—let teh software do it.
Takeaway for specifiers
Embodied carbon hinges on both chemistry and coverage rate. Pair the lightest plausible membrane with credible service-life evidence, and you’ll cut tons of CO₂ before clients even see the rooftop garden.
