Kingspan Insulation
Kingspan Group

XP Series Fanfold Underlayment

XP Series Fanfold Underlayment header

For the best fanfold siding underlayment available, choose the XP Series. The extruded polystyrene (XPS) foam offers superior stiffness, so your siding job has the smoothest finish possible. The underlayment is extra durable, thanks to flexible plastic facers on both sides. Plus it’s perforated to allow moisture vapor to escape. The cut-and-fold hinge design ensures it lays flat. A perforated reflective facer that can enhance thermal performance is also available.

TYPICAL PHYSICAL PROPERTIES
Property Test Method XP14 XFP14 XP38 XFP38
R-Value
(°F-ft²-h/Btu)1
ASTM C 518
(@75°F Mean
Temperature)
1.0 3.0 1.5 3.6
Water Vapor Permeance
(perm)
ASTM E 96
Procedure A
1.7 1.7 1.3 1.3
Water Absorption
(max,% by Volume)
ASTM C 272 2.0 2.0 2.0 2.0
Compressive Strength
(psi @ 10% deflection)
ASTM D 1621 12 12 14 14
Fire Characteristics2
Flame Spread
Smoke Development
ASTM
E 84/UL 723

25
250

25
250

10
45-140

10
45-140
DIMENSIONS / PACKAGING
XP14 XFP14 XP38 XFP38
Length3 50' 50' 50' 50'
Width3 4' 4' 4' 4'
Nominal Thickness 1/4" 1/4" 3/8" 3/8"
Square Feet/Pallet 9,000 9,000 6,000 6,000

1 Specimens were aged and tested in accordance with FTC Rule (16 CFR, Part 460). The R-values shown for GreenGuard®-FP1450, GreenGuard®-XFP14, GreenGuard®-FP38, and GreenGuard®-XFP38 are system R-values calculated in accordance with the “ASHRAE Handbook of Fundamentals” using a ½” uniform, parallel dead air space. The R-values of these products installed without the benefit of a dead air space are 1.0 (GreenGuard®-FP1450 and GreenGuard®-XFP14) and 1.5 (GreenGuard®-XFP38).

2 These numerical flame spread and smoke ratings are not intended to reflect hazards presented by these materials under actual fire conditions (core data).

3 These dimensions apply to each fanfold bundle.