Below-Grade Solutions

Foam Insulation for Below-Grade Applications

Foam Sales Group fabricates precision-cut foam insulation designed for foundations, slabs, and other below-grade systems, delivering durable, moisture-resistant solutions with project-specific accuracy and nationwide support.
Worker inspecting foundation with insulation and building materials in background.
Below-Grade Applications

How Foam Is Used in Below-Grade Insulation

Foam insulation plays a critical role in below-grade construction by providing thermal protection, moisture resistance, and long-term durability in demanding environments. Rigid foam boards are commonly used along foundation walls, beneath slabs, and around structural elements to help reduce heat loss, control moisture intrusion, and support the overall performance of the building envelope.

Provides thermal insulation for foundations and slab-on-grade systems
Resists moisture absorption in below-grade environments
Helps maintain consistent R-value over time
Supports long-term durability in contact with soil and concrete
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Products

Our Below-Grade Insulation Products

Explore our selection of foam insulation products we fabricate and distribute with materials cut to project specifications and delivered nationwide.
Insulation foam board for roofing systems by Foam Sales Group. High-quality Styrofoam for durable, e.

DuPont™ STYROFOAM™ Brand PERIMATE™ XPS Insulation

DuPont™ STYROFOAM™ Brand PERIMATE™ XPS Insulation is a high-performance extruded polystyrene board engineered for foundation and below-grade insulation systems. Designed to deliver long-term thermal performance and moisture resistance, PERIMATE™ insulation helps protect foundation walls while improving overall building energy efficiency. Its integrated drainage design allows water to move downward along the insulation surface, supporting effective moisture management in foundation assemblies.
Closed-cell XPS insulation with long-term R-value retention
Integrated vertical drainage channels for improved moisture control
High compressive strength for demanding foundation applications
Moisture-resistant design suitable for exterior and interior foundation walls
Information Sheet(s):
Perimate
Close-up of King Sheet GreenGuard Latex Mattress Topper with detailed label and eco-friendly packaging.

Kingspan GreenGuard® GG XPS Insulation Drainage Boards

Kingspan GreenGuard® GG XPS Insulation Boards are high-performance, closed-cell extruded polystyrene solutions designed for durable, long-term thermal performance in demanding applications. Manufactured by Kingspan, these boards are available in multiple compressive strengths (25, 40, and 60 psi) to support a wide range of below-slab, cavity wall, and foundation systems while maintaining excellent moisture resistance and insulating value over time.
Closed-cell XPS insulation available in 25, 40, and 60 psi compressive strengths
Delivers R-5 per inch with long-term thermal performance
Highly moisture resistant for below-grade and foundation applications
Available in multiple edge profiles and pre-cut formats for installation flexibility
Information Sheet(s):
GG25
GG40
GG60
House exterior showing new insulation and window openings during construction.

Insulfoam® EPS Insulation Boards (Exterior Grade & Tongue-and-Groove)

Insulfoam® EPS insulation boards provide versatile, cost-effective thermal solutions for below-grade, wall, and specialty construction applications. Manufactured by Insulfoam, these expanded polystyrene (EPS) products are designed for durability, dimensional stability, and long-term performance, with options including exterior-grade boards and tongue-and-groove profiles for enhanced fit and continuity.
EPS insulation designed for exterior, below-grade, and wall applications
Available in standard exterior-grade and tongue-and-groove edge profiles
Lightweight, durable, and easy to handle on site
Supports consistent thermal performance across a wide range of applications
Information Sheet(s):
Insulfoam Exterior Grade
Insulfoam Tongue & Groove
Efficient ThermalStar insulation panels for wall insulation applications.

Atlas ThermalStar® XPS Insulation (E, E+, G+, X, X+)

Atlas ThermalStar® XPS Insulation boards deliver reliable thermal performance and moisture resistance for commercial roofing, wall, and below-grade applications. Manufactured by Atlas Molded Products, ThermalStar® E, E+, G+, X, and X+ products are engineered as closed-cell extruded polystyrene solutions that retain insulating performance over time, even in demanding environments where durability and consistency are critical.
Closed-cell XPS insulation available in ThermalStar® E, E+, G+, X, and X+ options
Provides consistent R-value performance for commercial applications
High moisture resistance for long-term durability
Suitable for roofing, wall systems, and below-grade insulation assemblies
Information Sheet(s):
ThermalStar® E
ThermalStar® E+
ThermalStar® G+
ThermalStar® X
ThermalStar® X+
Fabricated to Spec

Our Fabrication Capabilities

Foam Sales Group fabricates below-grade insulation products to exact project specifications, ensuring consistent performance in demanding subsurface environments. Our precision fabrication process supports OEMs and distributors with materials that are ready for installation, helping reduce waste and streamline field execution.

Precision cutting to match foundation and slab requirements
Custom sizing for walls, footings, and sub-slab applications
Consistent thickness and tight tolerances across all orders
Coordinated fabrication and nationwide distribution
A construction worker in a yellow safety vest and red helmet carrying insulation board labeled Styrofoam through a wooded environment.
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Years of Innovation in Foam Fabrication
Who We Serve

Industries We Support

Foam Sales Group works across multiple industries, delivering precision-fabricated foam solutions tailored to the unique demands of each application.
Styrofoam plazamate xr product logo image4

Construction

We supply precision-cut insulation for commercial roofing, wall, and below-grade systems, supporting OEMs and distributors with materials their project teams rely on in the field.
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OEM Manufacturing

FSG partners with manufacturers to fabricate custom foam components that integrate seamlessly into OEM products, assemblies, and production workflows.
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Theatrical Sets & Props

From sculpted sets to detailed props, we provide specialty foam fabrication for the entertainment industry, combining precision shaping with responsive, service-driven support.
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Common Questions

Below-Grade Insulation Foam FAQs

Here are answers to some of the most frequently asked questions about our foam insulation solutions.

Below-grade applications typically use XPS and EPS insulation due to their moisture resistance, durability, and ability to maintain thermal performance in contact with soil and concrete.

Below-grade environments are constantly exposed to moisture. Using closed-cell foam insulation helps resist water absorption, maintain R-value over time, and protect the foundation system.

Yes. Foam Sales Group fabricates below-grade insulation to project specifications, including custom sizes, thicknesses, and profiles to fit foundation walls, slabs, and structural details.

We supply below-grade insulation through OEMs and distributors nationwide. Contractors and project teams receive materials through these partners as part of the overall building system.

Below-grade insulation is fabricated and shipped in coordination with project schedules, ensuring materials arrive on time and ready for installation.

Man applying Kingspan GreenGuard LG insulation panels to exterior wall.
Ready to Get Started?

Let’s Build Your Next Project Together

Connect with Foam Sales Group to discuss your fabrication needs, request a quote, or explore partnership opportunities — our team is ready to deliver precision, reliability, and nationwide support.