Hi Dan1979,
[quote]I do understand what you mean and I appreciate that you try to open my eyes to actually try to figure out for myself what I want.
My biggest concern is that in my zone there is absolutely no store, and no matter how much I will try I will not be able to see a latex topper mattress for a quite long time. However, if I would know what to look for, I could make a list of stores which are worth to look for and actually go and test.[/quote]
Post #2 here has links to some of the theory behind different types of designs but these are only generic and not specific to any individual. Either your own personal testing or a more detailed conversation with an online retailer or manufacturer that you trust has integrity is the only way to make your design choices. The goal is not so much to design a mattress yourself because this could take years of study and experience but more to trust your own testing or if you aren’t able to test a mattress locally then to trust the manufacturer or retailer you are dealing with and that they will give you reliable information.
Normally an 8" - 9" latex mattress doesn’t need a topper. It would have a combination of a firmer latex core and a softer latex comfort layer. The typical size for a latex core is 5.5" - 6" (that’s the size of the mold they are poured in) and then the top layer on top of this (for those that need it at all) would be in the range of 2" - 3". The firmness level of both the support core and the top layer would depend on the person and their body type, sleeping style, and their personal preferences. There are no “rules” or “theory at a distance” that can predict with any certainty how a mattress will feel of perform for any particular person. People are just too different.
The durability of a mattress will depend on the materials (see post #4 here for the different factors that are involved in durability). The suitability of a mattress in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) depends on the design. If a design is suitable for you (regardless of materials) and the materials are good quality then the feel and performance of the mattress will last much longer. You can test for the suitability of a mattress but you need to know the materials inside it to know whether they are durable and this information would come from the retailer or manufacturer.
I personally wouldn’t buy a mattress if I didn’t know the specifics of what was inside it well enough that I could identify any weak links in the mattress. There are many manufacturers who will tell you what you need to make an informed desicion and many who won’t … I would only deal with the ones who will.
There are no rules here. In most cases it will be somewhere in between 6 and 12 inches depending on the design that works best for you. Post #4 here has more about the effect of thickness and some of the previous links have much more information about different mattress designs. Post #7 here may also be worth reading.
Again the thickness of each layer is only one of many factors that will determine the feel of the mattress and by itself has little meaning. In very simple basic constructions you would typically see about 2" to 4" of latex over a polyfoam support layer but this will depend on all the different factors that are involved in designing a mattress.
There are too many types of pocket springs to even be able to begin to speculate because each of the hundreds of different versions may need a different combination of foam on top. I personally prefer steel edge support (such as firmer coils around the edge) but if it is polyfoam then higher density would be more durable (1.8 lbs and higher).
Phoenix