When every penny counts, you can rely on the performance of our most economical fanfold siding underlayment. The Q-Series products have an extruded polystyrene foam (XPS) core with high-impact polystyrene capsheets on both sides, which make it one of the most durable products currently available. These products are also perforated to allow potentially harmful moisture vapor to escape so that it does not become trapped in the wall.

Q250 & Q350 Fanfold

  • Nominal 3/8” thick extruded polystyrene board for the 3/8" Fanfold
  • Nominal 1/4" thick extruded polystyrene board for the 1/4" Fanfold
  • Lightweight, durable...cuts clean and easy
  • Convenient 4’ x 48’ fanfold
  • XPS performance... economical price
  • Made of synthetic materials that are generally not recognized as providing a food source for insects, fungus, mold or mildew
  • Perforated to allow moisture vapor to escape
  • Provides a smooth, level nailing surface for new siding
  • Both have a reflective surface on one side for added energy efficiency

1/2” XPS Insulation Board

The XPS insulation board offers an R–value of 5.0 per inch of thickness and is ideal for a variety of applications including below slab, below grade along the foundation, inside basement walls, exterior insulation over wood sheathing and residing.

Rigid extruded polystyrene insulation (XPS) can be used as general purpose insulation for roofing, wall and foundation applications requiring a minimum compressive strength.

  • R–value of 5.0 per inch of thickness.
  • Continuous insulation (Ci) for above grade walls, as well as below grade walls and floors.
  • Provides an extra barrier against moisture infiltration.
  • Each insulation product achieves the required fire performance for its intended application.