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Hints & Tips
Built-Up Roofing


 
  1. Store roll materials on end and up off of the roof. Keep material covered with a water-proof tarpaulin.
  2. Install crickets on the upslope side of all large equipment to help with water removal.
  3. Keep all oils, greases, and chemicals off of the roof.
  4. Always replace all flashings.
  5. Mechanically-fasten all base flashings at approximately eight inches (8") on center.
  6. Keep the Equiviscous Temperature (EVT) where it’s supposed to be.

ASPHALT – ASTM D 312

Asphalt Type

Mop Application ( F)

Mechanical Spreader Application ( F)

Type I Dead Level

350 25

375 25

Type II Flat

400 25

425 25

Type III Steep

425 25

450 25

Type IV Special Steep

450 25

475 25

COAL TAR – ASTM D 450

Coal Tar Type

Mop Application ( F)

Mechanical Spreader Application ( F)

Type I Pitch

360 25

380 25

Type III Bitumen

375 25

400 25

  1. When using rigid board roof insulation, stagger and offset each joint the maximum amount possible. No joints should be closer than six inches (6").
  2. When mopping polyisocyanurate insulation to a concrete roof deck, you should mop only four foot (4’) by four foot (4’) boards, not four foot (4’) by eight foot (8’).
  3. Gravel stop should be mechanically fastened in two staggered rows of 6" (15.24 cm) on center.
  4. Set your gravel stop in mastic and put mastic between each seam. Flash the gravel stop with TWO (2) plies. The first should extend 4" (10.16 cm) past the inside edge of the flashing and the second should extend 8" (20.32 cm) past the inside edge of the flashing.
  5. Replace plywood decking in whole sheets only – don’t piece it. This will help maintain the structural integrity of the roof deck.
  6. Consider a vapor retarder when the relalative humidity inside is 45% or more and the average January temperature is 40 F (4 C) or less.
  • Vapor retarders should be completely sealed at all side and end laps, and at all roof perimeters and penetrations.
  • All edges of all insulation installed on top of the vapor retarder should be sealed completely.
  • Vapor retarders should have close to a zero (0) perm rating.
  1. It is recommended that end laps be a minimum of 12 inches (30.5 cm).
  2. Don't leave treated wood uncovered for too long a period of time because it can warp easily.
  3. There should be around 30 pounds per square of bitumen between plies (15 kg per metric square).
  4. If you are installing an aggregate surfacing, the flood coating should be around 60 pounds per square (30 kg per metric square).

 

  
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