GreenGuard XP Series Fanfold Underlayment 0.375″ x 4′ x 50′

XP Series Fanfold Underlayment- Reflective Facer 1-Side

  • Superior stiffness for the smoothest finish
  • Plastic facers on both sides enhance durability
  • Available with a reflective coating that qualifies as a radiant barrier
Add to Quote
SKU: 50462 Category:


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.

Kingspan GreenGuard® XP14 Siding Underlayment comprises ¼” thick closed-cell polystyrene (XPS) with perforated capsheets on both sides. It is configured in fanfolded bundles 4’ x 50’ with
cut-n-fold hinges. It is lightweight and easy to cut and install. It is designed to be used as a “leveling board”, added insulation and added moisture protection in installation of new vinyl siding over old siding. It is available with a reflective surface on one side, Kingspan GreenGuard® XFP14 Siding Underlayment, for added energy efficiency. Superior Stiffness for the Smoothest
Finish Panel rigidity, water-resistance, durability, easy cutting and excellent lay-flat properties make this product the very best fanfold siding underlayment.

Product Data Table

Typical Physical Properties
Property Test Method XP14 XFP14 XP38 XFP38

(°F.ft².hr / Btu)1

ASTM C 518
(@75°F Mean Temperature)
1.0 3.0 1.5 3.6
Water Vapor Permeance
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 Developed
ASTM E 84/UL 723 25
Dimensions / Packaging
XP14 XFP14 XP38 XFP38
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

Product Data Sheet

Installation Guide

Safety Data Sheet


There are no reviews yet.

Be the first to review “GreenGuard XP Series Fanfold Underlayment 0.375″ x 4′ x 50′”

Your email address will not be published. Required fields are marked *

Go to Top