You would think that toppers made of memory foam last as long as the beds made of the same material. But this is not the case. Not even Tempur-Pedic toppers last as long as their mattress counterparts. All other things being equal, a memory mattress topper has a shorter lifespan because:
Thickness - Memory foam toppers are generally thinner than the foam layers used in mattresses. Toppers that are too thin (only 1-2 inches thick) wear out quicker because when the cells at the top crumble, there is a less memory foam underneath to take their place and provide support.
Overlay - Memory toppers are generally laid over an existing mattress or bed. If the mattress underneath is already worn out and shows sagging, the topper will simply follow that contour and make the sag even more pronounced because of its soft nature. That may take some time to become permanent.
Overweight - Heavy and obese people may speed up the process by adding extra pressure to the visco foam topper. While a memory mattress is held up by a highly resillient core, the topper is held up by air, springs or whatever else the bed is made of. Extra weight also makes the open cells crumble quicker than they would under the average person.
You can expect a viscoelastic foam topper to wear out in 18-36 months.
Most viscoelastic toppers, however, are not usually made of the same quality grade material as beds and mattresses are. This means they don't last as long. Viscoelastic material is very expensive to make and usually used to make only beds and mattresses.
Toppers, however, are generally much cheaper and using Tempur-style foam of the highest quality would make it economically unrealistic for manufacturers. Tempur Pedic brand mattress overlays, however, are made of the same NASA-evolved foam technology as Tempur mattresses. There is little information to indicate whether or not other mattress companies use the same grade foam in their toppers.
Bottom line, a visco memory foam bed topper will continue to provide support and comfort without sagging for 1.5-3 years, as long as it's:
A Critical Eye On The Latest Mattress Technologies
What affects the expected lifetime of memory mattress pads and does a Tempurpedic overlay last longer? The answer is years and years as long as it's made of better quality, higher-density foam.
Many manufacturers claim Swedish foam was first used by the NASA Space Program to boost sales for their visco foam beds.
NASA never did use that basic material in the 1960s. NASA bedding or space bedding technology simply does not exist as such.
The truth is the Swedish Tempur-Pedic company did eventually come up with a reliable formula now used in the best-selling Tempur mattress.
While Tempurpedic beds are commonly known to use Swedish foam bed technology, not all such products made in Sweden are made of the so-called NASA bed foam.
How can you check if your purchase as good as a authentic Tempur bed? You can try the wine glass test, the egg test, or the fridge test.