← Wall & Roof Systems
R-~3.5/inDesigned — Not Yet Built

Denim/Cotton Scrap (shop rag shred)

Fire: Cotton chars in place — safe; poly-blend content must stay low, see sort checklist

Moisture: Requires vapor barrier — packs down and stays wet if soaked

Free if diverting your own shop rag stream

Shred pile — yes (Must be clean, dry, mold-free)

Denim, Cotton, Canvas, Linen, Wool, Cotton-dominant poly blends

Shred pile — no

  • High-poly-content synthetics (100% polyester, nylon, acrylic fleece, athletic wear) — melt-and-drip is a worse fire failure mode than charring
  • Chemically flame-retardant-treated fabric — unpredictable breakdown once shredded/sealed
  • Vinyl, pleather, laminated or plastic-backed fabric
  • Moldy or heavily soiled items
  • Hardware (buttons, zippers, snaps, underwire) — strip before shredding

Borax/boric acid soak-and-dry before bagging for any permanent wall-cavity use

Verify: borate treatment mandatory before permanent wall-cavity use, not optional