FanFold by Plasti-Fab® is designed to provide a continuous insulating underlayment that will help to reduce air leakage that can create drafts that carry dust and dirt into the building envelope.

FanFold by Plasti-Fab® consists of a Type 1, expanded polystyrene (EPS) insulation core material (R-value of 3.9 (75 degrees) and 4.2 (40 degrees) per inch with a thin film laminated to both sides. The branded film includes horizontal & vertical gridlines spaced at 51 mm (2’’) on centre to assist with installation. FanFold is manufactured by Plasti-Fab® so that each piece folds into a stack that can be handled easily. On the jobsite Fanfold opens into a 1.22 m x 3.66 m (4 ft x 24 ft) section that covers a large area quickly.

All of these features add up to make FanFold one of the most versatile products on the market today.

  • Available in 1.22 m x 3.66 m (4 ft x 24 ft)
  • Insulation Thickness: 3/8, 1/2 in.
  • Bundle includes: 2 pcs , 192 sq ft total coverage
  • Superior lay-flat design provides smooth surface for installation of new siding over old
  • Quick and easy application for labor saving efficiency
  • Lightweight, easy handling and installation

Material Properties of FanFold® Insulation

Material Property Units Test Method Property Values
Nominal Density pcf ASTM C303 1.00
Compressive Resistance
Minimum @ 10% Deformation
psi ASTM D1621 10
per inch thickness at mean temperature
40°F (ft2•hr•0F/Btu) ASTM C518 4.2
75°F 3.9
Water Vapour Permanence
Perm ASTM E96 5.0
Flexural Strength
psi ASTM C203 25
Dimensional Stability
% linear change ASTM D2126 2.0
Water Absorption
% by volume ASTM C272 4.0
Oxygen Index
volume % ASTM D2863 24
pcf ASTM C303 0.90
Flame Spread Index
ASTM E84 <25
Smoke-Developed Index
Thermal Resistance for Some Common Thicknesses
Millimeters RSI Inches R-Value
19 0.49 3/4" 2.81
25 0.65 1" 3.75
38 0.98 1 1/2" 5.63
50 1.30 2" 7.50
75 1.95 3" 11.25
Other Standard & Custom thicknesses available upon request.
Standard sizes range from; 2x4,2x8,4x4,4x8.

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