The Guide to Layering Foam for Custom Comfort

Learn the Basics: Foam Terms You Need to Know

Before you start layering, it’s essential to understand a couple of key foam terms:

• Density: How much material is packed into the foam. Measured in pounds per cubic foot (PCF), this tells you the foam's durability and longevity. We consider high-density foam (1.8 PCF or higher) to be ideal for long-lasting, supportive cushions.
• IFD (Indentation Force Deflection): This measures how firm or soft the foam feels. A low IFD (like 15) is very soft, while a high IFD (like 60) is very firm.

Not sure what those terms mean? Check out our guide:

• “Foam Series: Choosing the Best Foam for Cushions — 5 Key Terms to Know”

We also recommend reading:

• “Foam Series: Comparing Types of Upholstery Foam” 

This blog explains the different CushionRite® foam options available at Sailrite and which ones are best for your project.

The Benefits of Layering Foam

Layering foam allows you to:

• Customize firmness and comfort.
• Add thickness without sacrificing support.
• Improve moisture resistance (especially important for boats and outdoor use).

Want to test layering combinations before you commit? Order samples from our product pages. Simply find the foam you're interested in, choose your desired firmness, and select the 6" x 6" (Sample) option.

How to Layer Foam: General Guidelines

When layering, start with a firmer foam on the bottom (higher IFD) for support, then add a softer foam on top (lower IFD) for comfort. Think of the base foam as a box spring — it stabilizes the cushion even if the top layer compresses over time.

Pro Tip: Add a layer of Moisture Prevention Underliner (#121766) at the very bottom (underneath the cushion cover). This breathable mesh promotes airflow and prevents condensation, mold and mildew — especially important in marine settings.

Choosing the Right Foam: Key Layering Types

In all our layering combinations, we never mix CushionRite® Premium Upholstery Foam (a high-density polyurethane foam) with CushionRite® Dry Fast Antimicrobial Foam (a reticulated, open-cell foam). Here’s why:

• Use Dry Fast if your cushion or mattress will be exposed to significant moisture — its open-cell structure dries quickly and resists mold.
• Use Premium if you want maximum durability and long-lasting comfort — ideal for indoor, dry environments, or for liveaboard boaters who prioritize longevity.
• While Premium and Dry Fast are common, you can also use our other foams. CushionRite® High Resilience (HR) Foam makes an exceptionally comfortable, springy top layer for luxury projects.
   

Layering Examples From the Sailrite Team

The Basic Boat Mattress Formula

If you’re looking for a thinner, budget-friendly boat mattress and don’t sleep on it regularly, this simple 3-layer formula is a great place to start:

• Top Layer: 2" CushionRite® Premium Upholstery Foam (Medium or Firm) OR 2" CushionRite® Dry Fast Antimicrobial Foam (Medium)
• Bottom Layer: CushionRite® Premium (Extra Firm) OR CushionRite® Dry Fast (Firmest)
• Base (Outside Cover): Moisture Prevention Underliner

This combo works well when headroom is limited or the mattress isn’t used every night.

Matt Grant's Recommendations (Sailrite VP)

Matt favors comfort and durability when layering foam. Here are his top two mattress builds:

Option 1: For Maximum Comfort (Low Moisture)

• Top Layer: 2"+ CushionRite® High Resilience Upholstery Foam (Extra Soft or Soft) OR CushionRite® Premium Upholstery Foam (Soft)
• Middle Layer: 1"-2" CushionRite® Premium Upholstery Foam (Extra Firm)
• Bottom Layer: 1/2" CushionRite® Flotation Antimicrobial Foam
• Base: Moisture Prevention Underliner

Option 2: For Wet Sleeping Berths (High Airflow)

• Top Layer: 2"+ CushionRite® Dry Fast Antimicrobial Foam (Medium)
• Middle Layer: 1"-2" CushionRite® Dry Fast Antimicrobial Foam (Extra Firm)
• Bottom Layer: 1/2" CushionRite® Flotation Antimicrobial Foam
• Base: Moisture Prevention Underliner

Eric Grant's Recommendations (Sailrite Project Guy)

Eric emphasizes long-term durability, especially for liveaboards. His advice:

• Use at least 3" of CushionRite® Premium Upholstery Foam (Extra Firm or Firmest) in any mattress you plan to sleep on frequently.
• Avoid using CushionRite® Dry Fast as the top layer unless you're dealing with serious moisture issues — it’s less comfortable than CushionRite® Premium.

Option 1: For Everyday Use

• Top Layer: 2" CushionRite® Premium Upholstery Foam (Medium)
• Bottom Layer: 2"-4" CushionRite® Premium Upholstery Foam (Firmest)
• Base: Moisture Prevention Underliner

Option 2: For Extra-Thick Mattresses (if Space Allows)

• Top Layer: 4" CushionRite® Premium Upholstery Foam (Medium or Firm)
• Middle Layer: 4" CushionRite® Premium Upholstery Foam (Extra Firm)
• Optional Layer: 1/2" CushionRite® Flotation Antimicrobial with drilled holes for airflow
• Base: Moisture Prevention Underliner

Upgrade Your Foam With a CushionRite® Foam Protector Cover

For a polished, professional finish, encase your mattress in CushionRite Foam Protector. This soft, quilted fabric:

• Feels like a store-bought mattress.
• Is 100% polyester, breathable and moisture-wicking.
• Comes in a wide 106" width — perfect for custom sizing.

Use it to sew a zippered box cover around your foam layers (excluding the Moisture Prevention Underliner, which stays outside the cover).

Shop CushionRite Foam Protector

Final Thoughts: Customize Your Comfort With Foam Layering

With CushionRite® foam and a little experimentation, you can build a cushion or mattress that meets your exact needs. Whether you're working on a boat, RV or home project, layering gives you full control over firmness, thickness and performance.

Still have questions? Our team is here to help! Contact us via chat, phone, or email — or drop a comment below.

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