The Foam Inside Your Outdoor Cushion Is Probably Wrong. What Should It Be?

Most outdoor cushion buyers focus on the fabric because it is what you see: it fades, it gets cleaned, it shows wear. But the reason many outdoor cushions become uncomfortable or soggy within a season or two is often the foam inside. Many ready-made cushions use foam meant for indoor furniture, which was never built for rain on a patio or in a garden.

Here is what the different foam types for outdoor cushions mean, why the difference matters, and what to choose when you order replacement foam or new outdoor cushions.

Quick answer: Outdoor cushions often go flat or soggy because they use indoor foam, which holds rain. For cushions left out in the weather, choose reticulated Dry Fast foam, which lets water drain straight through and dries quickly. Pick a dense foam that holds its shape, about 2″ to 3″ thick for dining chairs and 4″ to 5″ for lounge and sofa seats, and look for CertiPUR-US certification.

Order Dry Fast foam cut to size, or browse all custom cut foam.

Why does regular foam fail in outdoor cushions?

Standard polyurethane foam, the kind in indoor sofas and mattresses, has small cells that hold water. That is fine indoors. Outdoors, when rain soaks a cushion with standard foam, the foam holds the water and can stay wet for a long time. That makes a cold, damp seat, encourages mildew and wears the foam out faster through repeated wetting and drying.

What is Dry Fast foam, and how is it different?

Dry Fast foam is a reticulated polyurethane foam. Reticulation removes most of the thin cell walls inside the foam, leaving an open, three-dimensional mesh. Water runs straight through it instead of being held, so a Dry Fast cushion drains and dries quickly after rain.

That makes it the right foam for pool and deck seating, boat and yacht seating, patio and garden furniture, outdoor swing beds and anywhere cushions stay out in the weather.

When is Dry Fast foam the right choice?

Choose Dry Fast foam when cushions are regularly left out in the rain, when they need to be usable again soon after a storm, or when they sit in a damp place like a pool deck or boat. Typical uses: deep seat lounge chairs, pool loungers, outdoor sectionals, marine seating, and outdoor dining chairs in rainy climates.

For cushions that are always brought inside or covered before rain, such as on a covered porch, a high-density foam is usually more comfortable and costs less. Dry Fast foam is firmer, so it is worth it where drainage actually matters.

What foam density is right for outdoor cushions?

Foam density, in pounds per cubic foot (lb/ft³), tells you how well foam keeps its shape over time. Low-density foam can sink in the middle after regular use; high-density foam holds its profile much longer. Density is separate from firmness (ILD): two foams can have the same density and feel different. See how our foams compare on the custom foam page.

What foam thickness is right for outdoor seat cushions?

• Outdoor dining and occasional chairs: 2″ to 3″.
• Lounge chair seats: 4″ to 5″.
• Sofa seats: 4″ to 5″.
• Back cushions for deep seat furniture: about 4″.

A thin cushion on a lounge chair flattens under full body weight and feels hard. A thicker cushion keeps some cushioning even when you sit back, which is the difference between outdoor seating that feels comfortable and seating that feels like a pad on a frame.

What is CertiPUR-US certification, and does it matter?

CertiPUR-US is a certification program for polyurethane foam that tests for specific harmful substances and emissions and for durability. CertiPUR-US certified foam has been independently tested to those standards. When ordering replacement foam, look for the certification alongside the density and firmness, rather than relying on density claims alone.

Why foam and fabric work together

Dry Fast foam drains quickly, but if the cover fabric has a waterproof backing, water can be trapped between the fabric and the foam. Pair Dry Fast foam with a breathable outdoor fabric such as Sunbrella upholstery fabric, which repels water but lets the cushion dry. For more, read weatherproof outdoor fabric choices and the most common outdoor cushion buying mistakes.

How to store outdoor foam cushions

Before winter storage, clean the covers, let the cushions dry completely, and check the seams for mildew. Store cushions with airflow: stand them on edge on an open shelf, or stack them with spacers, rather than sealing them in a closed bag or bin, which traps moisture. A vented storage bag in a covered space works well. See all Sunbrella outdoor cushions.

Buying cushions for a hotel, restaurant or other commercial space? Commercial seating often has to meet flammability rules as well as stand up to weather. Read fire codes for commercial cushions: CAL TB 117-2013, NFPA 260 and UFAC, or see our hotel and resort pool cushions.

Frequently asked questions

Can I order outdoor foam on its own?

Yes. We cut foam only, without a cover, to the size you need. Measure the existing foam edge to edge, or the inside of your cover seam to seam, and order to that size. Choose Dry Fast foam for cushions left outside. Order custom cut Dry Fast foam to your measurements, cut within ¼″ (maximum ±1″).

Is Super Soft foam suitable for outdoor seat cushions?

No. Super Soft foam is made for back cushions only, where it adds a relaxed, sink-in feel. On a seat it compresses too far and flattens quickly. For outdoor seats, use Dry Fast foam where cushions get rained on, or high-density foam under cover. If a seat feels too firm, go thicker rather than softer. See our cushion size and foam guide.

How long does custom-cut foam take to arrive?

Foam for standard shapes ships in 2–3 weeks. Custom shapes from a template take 5–6 weeks. Foam ships vacuum-packed, so unwrap it on a flat surface and allow 12–18 hours for it to expand fully before you fit the cover. Our US foam is CertiPUR-US certified.