Living Review durability forecast — modeled, not observed
How an all-foam stack ages, and how sure we are
Assumptions: two adults totalling under about 400 lb, nightly use, a solid or closely slatted base that meets Saatva’s rules, rotation twice a year, no liquid damage. Inputs are Saatva’s layer thicknesses, its 5-lb core claim, the lower-layer densities NapLab lists as manufacturer specs, and the labs’ durability views. No ILD figures and no long-term or compression test of this build are published, so this is a qualitative scenario, not a service life, a probability, or a score.
Modeled first change
The edge and the hip zone of the lighter foams, not the 5-lb core. A border already measured at 6.25 in of seated compression is where a slope shows first, and the 1.5–1.8 PCF transition and base layers lose height under concentrated load sooner than the core above them.
Modeled countermeasures
With no coils, there is no spring fatigue or noise to develop. The dense core should hold its shape longer than lower-density memory foam would. Rotation spreads wear, and NapLab reports the stack has not changed since 2015, so owner experience accumulated over a decade describes this same build.
Uncertainty and update rule
Confidence is moderate on the direction, low on the timing. Sleep Foundation’s 7 of 10 durability rating is the only lab score; the lower-layer densities are reported, not verified. We will revise this section if Saatva changes the layer list, publishes densities, or if a lab posts a long-term or compression test of the current bed.