Hi masher,
[quote]We are happy with our present Tempurpedic but it’s dry rotting from old age. It’s around 15+ years old. It looks to be 9 inches thick - 5" convoluted base, 3" mid layer and 1" top layer. If my research is right the base layer is 2.2lb polyfoam, the middle layer is 5.5lb memory foam and not sure about the top layer.
Is it possible to reproduce something close to this mattress diy?[/quote]
There is more about the different ways that a mattress can “match” or approximate another one in post #9 here. While it may be fairly simple to match the quality and density of each of the layers … it would be much more difficult to match or approximate the “feel” and performance of the mattress.
You would need to know the exact specifications of all the layers and components in your Tempurpedic mattress including the thickness, type, and density of the foam layers, the firmness of each layer, the specifics of the convoluting in the base layers, the specifics of the temperature sensitivity and response rate of the memory foams, and the specifics of the cover. Once you had this information then you would need to have access to the exact same type of layers and components to duplicate the mattress. This is very unlikely since Tempurpedic doesn’t provide all the information you would need and they don’t sell their foam layers to other manufacturers or foam suppliers and even if you had all this information you probably wouldn’t be able to find memory foam layers that had the same response and feel as the Tempurpedic memory foam. There is more about the different properties of different types and chemical formulations of memory foams in post #9 here and in post #8 here.
Without duplicating all the layers and components in a mattress you would be involved in a process of trial and error because the only way to know how close any combination of layers would feel to you would be based on your own personal experience.
If you are attracted to the idea of designing and building your own DIY mattress out of separate components and a separate cover then the first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
If you decide to take on the challenge then you would need to use the specs of your Tempurpedic that are available to you even though they are incomplete (I don’t know which specific Tempurpedic mattress you have but if you let me know I may have some information about the layers inside it) or use a “bottom up” approach along with some trial and error with different polyfoam and memory foam layers (see post #2 here) until you find a combination that is “close enough” for you.
Phoenix