What do you put under a hybrid mattress?

Place a hybrid mattress on a solid, flat foundation that distributes weight evenly and keeps the coil system from sagging, most commonly a platform bed with slats no more than 3 inches apart, a solid-top foundation, or an adjustable base.

Hybrid mattresses combine innerspring coils with foam or latex layers, and that coil system needs firm, consistent support underneath. Slats spaced too far apart let the coil perimeter flex and drop, which accelerates edge breakdown and can void the warranty. A box spring made for traditional innersprings isn't the right call here; those flex slightly by design, and a hybrid doesn't need that give.

Hybrid mattress slat spacing: gaps must not exceed 3 inches to prevent coil sagging.
Adjustable bases are compatible with most hybrid mattresses, check the manufacturer's flex rating before purchase.
Traditional coil box springs are not recommended under hybrid mattresses; a rigid foundation is required.
Minimum recommended platform or foundation height for most hybrid mattresses: 5 inches of clearance above the floor for airflow.
Most hybrid mattress warranties are voided by unsupported foundations; solid slat or platform bases preserve warranty coverage.