Polyfoam (Polyurethane Foam)

Polyfoam (polyurethane foam) is the most widely-used material in mattress construction — almost every memory foam, hybrid, or innerspring mattress contains polyfoam somewhere in the build, typically as a support core or transition layer between comfort foam and the support layer.

Polyfoam is non-viscoelastic (it does not exhibit memory foam's slow recovery) and is simpler and cheaper to manufacture. It comes in three quality tiers: high-resilience (HR) polyfoam at 2.5+ PCF (durable, used in premium builds), high-density (HD) polyfoam at 1.8–2.4 PCF (mid-range), and conventional polyfoam at under 1.8 PCF (budget construction, short-lived).

Higher-density polyfoam is generally more durable and supportive but heavier and more expensive. Lower-density polyfoam is cheap and easy to manufacture but breaks down rapidly — the leading cause of mattress sagging within 3–5 years.

Polyfoam can be safely treated as a 'commodity' input — meaning a 2.5 PCF polyfoam from one manufacturer performs nearly identically to a 2.5 PCF polyfoam from another. The brand of the polyfoam doesn't matter; the density does.

Polyurethane foam is the workhorse of the industry and the layer where cost-cutting hides. It appears as a quilted top layer, a transition layer between comfort foam and coils, and as the entire support core of budget all-foam beds. Its quality varies more than any other component, and density is the only spec that reliably separates good from bad.

Below about 1.5 lb/ft³ in a support core, polyfoam compresses permanently within a couple of years — the single most common cause of the sagging that ends a cheap mattress's life. High-resilience polyfoam above 2.5 lb/ft³ is a genuinely durable, springy material that some sleepers prefer to latex. Same name, entirely different products.