How to Install Torch Ply Roof

Properly installed torch-ply roofing materials form a watertight membrane over leak-prone flat and low-slope roofs.
Rolls of tar paper and insulation usually underlay torch-down roof sheets.Rolls of tar paper and insulation usually underlay torch-down roof sheets.
Although installation appears as simple as heating and unrolling the torch-ply sheets, heating the torch-ply's tar-like membrane to the right temperature for adhesion requires careful attention. Additionally, safety precautions are paramount, as the torch's open flame presents serious fire risks. With an understanding of torch-down equipment operation and safe installation procedures, you can install a long-lasting torch-ply roof covering.

Step 1

Remove labels, tape or packaging materials from the rolls. Determine the direction of installation. For roofs with a slope of less than 1 inch per foot, install the rolls perpendicular to the roof's slope. For slopes greater than 1 inch per foot, install the rolls parallel to the roof's slope.

Step 2

Unravel the roll along the roof's edge or eave and position the roll in the desired installation position, overlapping the roof's ends and eaves as required by your roof's design. Cut the sheet to size with a utility knife if necessary. Roll both ends of the sheet toward the roof's center until the sheet forms two coils that sit back to back. Rerolling the sheet allows you to begin installation from the roof's center, working outward to the roof's edge.

Step 3

Set a fire extinguisher near the work area. Put on goggles and gloves. Turn on the torch's fuel supply and light the torch. Apply the torch's flame to the compound-coated, rear portion of one of the coils. Hold the torch approximately 6 inches from the roll and position roughly three-quarters of the flame over the roll and the remaining one-quarter over the roof deck's base sheet. Sweep the flame from end to end across the roll's backside.

Step 4

Touch the sheet's rear surface with a roofing trowel to determine whether the adhesive compound is melted and ready for application. Suitably heated compound is viscous and easily slips from the sheet. Alternatively, use visual cues to determine when the roll is sufficiently heated. Film-type sheets burn slightly green when ready, and sand-coated rolls often become slightly dark.

Step 5

Latch a roof hook onto a cool portion of the rolled roof sheet, and push or pull the hook to unravel the prepared portion of the sheet onto the underlying base sheet. Repeat the heating process and unravel the sheet across the roof. Repeat the heating and unraveling process for the opposite coil.

Step 6

Lap the sides of successive courses of roofing roughly 3 to 4 inches or as indicated by the strip of adhesive compound on the roofing sheets' upper surface. When lapping side seams, apply the flame in an L-shaped pattern, moving 12 inches down the side lap, across the roll end-to-end and then back up the side lap. As you unravel side laps, have a partner follow behind you and roll the seams with a seam roller.

Step 7

Lap consecutive sheets by 6 to 8 inches at their ends. Evenly heat both the installed sheet and the overlapping sheet. If both sheets are properly heated, roughly 1/4 to 1/2 inch of melted compound will squeeze from the joint when you press the overlapping sheet down.

Things You Will Need

  • Torch-down rolled roofing
  • Utility knife
  • Fire extinguisher
  • Goggles
  • Gloves
  • Roofing torch
  • Roofing trowel
  • Roof roll hook
  • Rolled roofing seamer

About the Author

Based in Hawaii, Shane Grey began writing professionally in 2004. He draws on his construction experience to write instructional home and garden articles. In addition to freelance work, Grey has held a position as an in-house copywriter for an online retailer. He holds a Bachelor of Arts in theater arts from Humboldt State University.