Hi KevinLewis
Welcome to our Mattress Forum! 
From the âsymptomsâ, you describe it seems that you are bottoming out on the 8" firmer support innerspring below. With someone that is in the heavier weight range and uses a softer or too thin of a comfort layer ⌠it would be much more likely that they would feel the firmness of the âstifferâ support layer underneath it. This is one of those âcounter-intuitiveâ circumstances where using softer foam can actually make a mattress feel firmer and cause it to feel like "sleeping on a board like my hips donât sink as far as they should "
First off, Iâd do a ground-up assessment to make sure that the components you are using are in good condition and that thereâs nothing else that may contribute to the issue.
~ Iâd make sure that you donât have sagging or weak spots in the foundation or box spring under your mattress.
~ Do you happen to know the specs of your spring unit? The number of coils, gauge, and coil manufacturer? ⌠It may give some additional clues to how to fine-tune the DIY. Pocket coils and latex can be a great combination but you would need strong coils and I think that the consensus with most manufacturers Iâve talked with is that pocket coils that would work well for most people may not be the best choice for higher weights unless it uses lower gauge/stronger coils. If you canât find the specs of this specific unit, we can make some assumptions about it. The unit should be firm/strong enough for your needs since in your first two years of use you had a âperfectly goodâ sleep (It appears that the initial support was a good match for you at the time of purchase and before the foams started breaking down). This said I would inspect the coil unit to make sure that the coils are in good condition.
I figured the bed was too firm and purchased another inch latex topper that is softer but it feels like it did nothing at all if not made it worse. Should i get a thicker topper perhaps? after the topper was added it felt worse and adding the two comforters doesnât seem to help as it did before. Iâm just at a loss here.
Your general approach is good but there are a few mattress essentials that escaped you when rebuilding your mattress.
~ Thickness and firmness go hand in hand (More details below)
~ Heavier people in general will need firmer, thicker, and denser comfort layers and firmer support layers than those who are lighter, and because no materials will last as long with much higher weights the quality and durability of the materials and components. So durability is even more important than with average BMI individuals.
~ Side sleeping individuals need more thickness as there is a much smaller surface area of contact with the mattress. This means that for the same weight, the pressure exerted is higher and it will cause side sleepers to sink deeper into the mattress. (Think high heel imprint depth in the snow as opposed to flat shoe depth) It is very likely that youâre both going through the softer layer on top and bottom out onto the firmer layer below.
~ For higher BMI range individuals I would avoid using more than an inch or so of softer latex on top, not only because youâll go through it to the firmer layers below but because it will wear out prematurely due to the higher mechanical stress.
All in all, sometimes just adding more thickness can make a difference because thicker layers can âactâ softer so with a slightly thicker mattress you can use firmer layers on top that are more adaptable to a greater range of weights and sleeping positions. See post #14 here for more about layer or mattress thickness.
People that have much higher body weights or larger body types may choose more than the âaverageâ thickness and may prefer the feel and extra adaptability of say 12-14" mattress. Thicker mattresses can also use firmer materials because thickness and softness are very related and work together. The thicker layers (or mattresses) can have a greater range of compression and are more âadaptableâ ⌠itâs also possible to use firmer top layers in a thicker mattress and still have good pressure relief because of the greater range of compression of the thicker mattress which can create a mattress with a firmer âsurface feelâ (that may be felt with hand testing but that still provides good pressure relief and adapts well to the body contours.
If you have more layers you can also rearrange or exchange them to fine-tune, youâre the performance and feel of your mattress.
As a higher BMI individual can go through the softer comfort layer very quickly and feel the firmness of the next layer underneath and might be better served by adding another 2-3" of medium-firm of Latex (or even firm, depending on your preferences) of Dunlop as a transition layer between the coil unit and the top medium latex layer that you already have. You didnât say what type of latex this is just keep in mind that Talalay Latex and Dunlop Latex have different âfeelsâ; Talalay is considered to be âbouncierâ(think the difference between angel food cake and pound cake)
The 1" inch of soft latex could still prove useful in fine-tuning the entire construction and add a bit more cushiness.
Many of the Trusted Members of the site carry toppers, as well as DIY components, and would be happy to assist you with your build. DIY Natural Bedding, DIY Mattress, and Latex Mattress Factory for latex layers, and Arizona Premium Mattress, Flexus, and SleepEZ, among others, for toppers. Itâs not unusual to need to exchange or switch around latex layers with a DIY as all layers work together. You can see This Article with an overview of how components fit together.
With a little more research and consideration, youâll be well on the way to finding the best combination of layering for your specific needs & preferences that will last you much longer.
Phoenix