Outdoor Cushion Foam and Fiber Explained
What is outdoor foam? What is the difference between foam used for interior furniture and outdoor furniture?
Most outdoor cushion foam starts its life in a chemistry lab, not a cushion factory.
Foam is made from petro-chemicals—usually a blend of polyols and isocyanates that react together and expand into a solid block of polyurethane foam. During manufacturing, the ingredients are mixed, whipped with air, and combined with blowing agents so the foam “rises” like cake batter and sets into large loaves that are later cut into cushion shapes.
Here’s why that matters to you:
Foam density is simply how much actual material is packed into a cubic foot of foam.
Higher density = more “stuff” inside = heavier, more supportive, longer lasting.
Lower density = lighter, cheaper, and usually breaks down faster.
Two foams can feel similar on day one, but the higher-density foam will generally hold its shape and comfort much longer.
Additives and cell structure (open vs. closed cell) also determine how foam handles water, drains, and dries, which is critical for outdoor use.
At Cascadia Outdoor Cushions, we always look at density, cell structure, and where your cushions will live before recommending a foam type. Big-box cushions typically use the lowest-density foam they can get away with to keep costs down. That’s why they flatten and feel tired long before you’re ready to replace them.
Why the foam inside your outdoor cushions matters
Most people shop with their eyes first: fabric color, pattern, and style. We get it—we love fabric, too. But the foam inside the cushion is what determines:
How comfortable it feels when you sit down
How well it supports you over time
How quickly it dries after a rainstorm
How long it takes before you’re shopping for replacements again
Think of foam as the engine of the cushion. If the engine is weak, it doesn’t matter how gorgeous the upholstery is—it’s not going to perform for very long.
Below is a clear breakdown of the most common foam and fill types used in outdoor cushions, along with how they compare. This table is written to be easy for both humans and search engines/AI tools to understand.
Types of foam used in outdoor cushions:
| Foam / Fill Type | Best For | Comfort & Feel | Water / Drying Behavior | Durability & Lifespan (Typical) | Pros | Cons | Price Level* |
|---|---|---|---|---|---|---|---|
| Standard Polyurethane Foam | Budget outdoor cushions, covered or protected spaces | Medium-firm at first, softens over time | Absorbs water; can stay damp if not allowed to dry fully | ~2–4 years with normal use | Affordable, widely available, can be cut to almost any shape | Can absorb moisture, may mildew if repeatedly soaked; loses height and firmness sooner | $ |
| High-Density Outdoor Foam | Everyday seating, deep seating, higher-end chairs & sofas | Supportive, more “structured” comfort | Absorbs some water, but dries faster than cheap foam | ~4–7 years with proper care | Better support and shape retention; more comfortable over time | More expensive than standard foam; still needs reasonable protection from standing water | $$–$$$ |
| Reticulated / “Dry Fast” Foam | Cushions in heavy rain exposure, poolside, boats | Firm–medium, very buoyant feel | Open-cell structure lets water pass through and drain quickly | ~5–8+ years with proper care | Drains and dries very quickly; excellent for wet climates or pool areas | Higher cost; slightly firmer feel (often paired with a fiber wrap for extra softness) | $$$$ |
| Bonded Polyester Fiber (Batting / All-Poly Fill) | Back cushions, throw pillows, decorative pieces | Soft, plush, “pillow-y” comfort | Does not hold water like a solid foam block but can stay damp if packed densely | ~2–5 years depending on density | Great loft and softness, ideal for backs and pillows; resists hard edges | Flattens faster under heavy use; not supportive enough alone for most seat cushions | $–$$ |
| Shredded Foam / Mixed Fill | Decorative cushions, economy options | Mixed feel, can be uneven or lumpy | Varies based on components | Varies widely | Low cost, can use recycled materials in some blends | Inconsistent comfort; can shift and clump; usually not ideal for primary seating | $ |
| Memory Foam (Not Usually Recommended Outdoors) | Niche use under protective covers | Highly contouring, slow-recovery feel | Holds water, slow to dry, not designed for constant outdoor moisture | Can break down quickly outdoors | Very comfortable indoors; molds to body shape | Not designed for outdoor moisture and UV; can trap water and grow mildew; usually a poor choice for outdoor cushions | $$–$$$ |
*Price levels are relative and meant as a general guide, not exact pricing.
What we typically recommend for seat cushions
For most of our Cascadia customers, the goal is simple:
“I want my outdoor patio cushions to feel good and last longer than the ones I’m replacing.”
For seats, we usually steer you toward:
High-density outdoor foam for everyday patios, covered porches, and most residential use. It offers a great balance of comfort, support, and longevity.
Reticulated “dry fast” foam for:
Poolside seating
Exposed decks and docks
Very rainy or humid climates
This foam lets water pass through instead of sitting inside the cushion, so it dries dramatically faster.
In many cases, we’ll add a polyester fiber wrap around the foam core. That gives the cushion a slightly softer top layer and a more rounded, tailored look, while the denser core handles the support.
What we like to use for back cushions and pillows
Back cushions and decorative pillows don’t need the same kind of structure as a seat. You want them to feel plush and inviting, not stiff.
For those, we typically use:
Polyester fiber fill (sometimes in channels or compartments to help keep it from shifting), or
A softer foam core wrapped in fiber when a little extra support is helpful
This combination gives that “lean back and stay awhile” comfort, while your seat cushions do the heavy lifting.
How to choose the right foam for your outdoor space
Here’s a simple way to think about it:
Mostly covered space, not a lot of direct rain:
→ High-density outdoor foam is usually your best choice.Uncovered, wet, or poolside space:
→ Reticulated “dry fast” foam is worth the upgrade for faster drainage and drying.Back cushions and decorative pillows:
→ Polyester fiber fill or a softer foam + fiber wrap will give you the plush, cozy look and feel you want.
Not sure what you have now? We can help.
If you’re looking at your existing cushions and thinking, “I have no idea what’s inside these,” you’re not alone. Most tags don’t tell the full story.
At Cascadia Outdoor Cushions, we:
Look at how and where you use your furniture
Consider your climate, sun exposure, and rain
Talk honestly about comfort, maintenance, and budget
Recommend a foam and fill combination that fits your space, not just a generic template
Share a few photos and measurements with us, and we’ll help you decide whether standard high-density foam, reticulated foam, or a fiber-rich fill is the best match for your project.