My wife (5’3 110lb side, back) and I (5’9 160 back) went with the Rocky Mountain Mattress Sensus 9 based on our reading here and testing. We graduated from a Costco Novaform which we loved originally but sagged after just 2yrs.
1.5wks in, I’m not getting the support I need as I wake up with some minor back pain, and the wife just doesn’t have the “sinking/molding” feeling she liked from our testings (we preferred the Tempurpedic Rhapsody) although she’s happy otherwise.
Talked to Lane at RMM and his analysis has the Rhapsody with 2" of 4lb over 3" of 5lb foam (which is different than what I’ve read here). I inquired about the 8lb Venus topper and he said it was softer than the 5lb Sensus.
So wanted your advice on a couple options to further tune our bed-
Add 1-2" of a med-firm latex layer under the 5lb Sensus. This would give me support but probably wouldn’t give us the molding feel the Sensus 5lb lacks.
Add 2" of Venus 8lb on top of the 5lb Sensus. This would give us more of a sinking feel and but not sure of enough support for me? Pricey option but durable. More similar to what I’ve read is the Rhapsody construction here.
Add 2" of some other slow-response topper (Aerus 4lb?) on top of the 5lb Sensus. A cheaper way to accomplish what Lane says is the Rhapsody construction, but less durable than the Venus.
Add 3" of Tempurpedic brand topper (I think is ~5lb) on top of the 5lb Sensus. I can buy this locally and test out and is cheaper than the Venus and hopefully more formulated to the Rhapsody sinking feel we prefer.
I’m debating between options 2-4 first, and then adding #1 later if those don’t solve my support issue.
I don’t see a Sensus 9 on their site … only a Sensus 8 and a Sensus 10. Based on your description though I’m assuming you mean your mattress has 3" of Sensus on top over 2 x 3" layers of polyfoam which is the description of the Sensus 8 even though the layers add up to 9" instead of the 8 they mention in the description).
The first step is to make sure you have clarity about exactly what you are looking to change.
If your issue is “primary support” (the type of support that stops the pelvic girdle from sinking in too far) … then this is usually a matter of fine tuning the deeper layers … not the top layers. An example of firming up the support layers would be to exchange the polyfoam layers on the bottom so that the firmer layer was closer to your body.
If your issue is “secondary support” (the type of support that fills in the gaps in the sleeping profile in all your sleeping positions such as the recessed lumbar curve or the waist or controls the distance of “travel” before your heavier parts reach the firmer support layers and are “stopped”) … then this is usually a matter of fine tuning the thickness and/or softness of the comfort layers. This could be done with a topper if you need to add to the thickness or softness.
If your issue is pressure relief … then this is also usually a matter of fine tuning the thickness and softness of the upper layers of the mattress. Once again … a topper can certainly help here.
All of these are interactive and each change will affect the others as well but this is the general idea of how to control the balance between primary and secondary support and pressure relief.
When you are fine tuning a mattress with a topper … it’s important to make sure you have identified exactly what you are wanting to change (primary support, secondary support, or pressure relief, or even just “feel”) and then using your best judgement (in combination with the guidance and help of the people who make the mattress or sell the topper because they have the best knowledge about the products they sell) about how it will affect the other qualities of the mattress so that you don’t end up fixing one issue and introducing another one completely. Usually changes that are “just enough” to improve what you want to change is the key to making changes that will have the least possible effect on the other qualities of the mattress and the balance between support and pressure relief for your particular body type and sleeping style.
So if your issue is primary support … then making the deeper layers firmer (such as re-arranging them) could be the “best” answer.
With the other two … a topper could help.
As far as I know and based on the Tempurpedic website information and other descriptions such as here … the Rhapsody uses 1.2" of their HD memory foam which is 7 lbs density on top of a 2.8" layer of their regular Tempur material which is 5.3 lbs. The Tempurpedic 7 lb memory foam by most standards (keeping in mind that memory foam responds to many variables including heat, humidity, pressure, and time) is also softer than their “regular” Tempurpedic memory foam. I would also keep in mind that other factors such as the speed of response of denser memory foams and the time it takes for them to become softer can also affect the perceptions of different people about how firm a specific layer feels to them. For example if you “slap” honey it will feel firm but if you press into it slowly then it will feel softer. Tempurpedic also doesn’t mention the IFD of their base layers which can also make a difference but it would be reasonable to assume that they are somewhat similar to what you have.
If you are looking for layers that are closer to the Rhapsody in terms of density and layering … then an additional 1" or so of 8 lb memory foam would be closer than what you have (this would give you 4" of memory foam in total of similar density which is the same as the Rhapsody but slightly different in layer thickness) but I would also keep in mind that different types of memory foams have different properties … even if the density is the same. Using density and layer thickness alone to “approximate” another mattress may not lead to your mattress having the same feel and performance as a mattress that uses memory foam of a similar density or even layer thickness but has different properties … although it would most likely be “closer” than what you now have. You can read more about the variations in the properties of different memory foams in post #8 here and post #9 here.
With Tempurpedic … the 4 lb is generally considered to be the softest followed by the 7 lb HD and their regular memory foam is the firmest although they also have variations of their regular memory foam in terms of “softness” (which is not that meaningful a term in the case of memory foam because of the variables that contribute to its firmness). This is similar to the 8 lb Venus being softer than the regular 5 lb Sensus.
So all of the options you mentioned seem well thought out and it seems you have correctly identified the tradeoffs between them (with the exception of using firmer support layers for better support and using 2" for your topper height instead of 1" which would be closer to the Rhapsody).
I think that the least “desirable” of your options would be #4 because it is nothing like any of the layering you are familiar with or have tested so it would be a complete unknown in terms of feel or performance. this doesn’t mean it couldn’t work for you … only that it has the most unknowns.
Option #1 would change secondary support and pressure relief to different degrees depending on the firmness of the latex you were considering. This would also be outside of your testing experience as well because of the differences between latex/memory foam hybrid comfort layers and comfort layers that used only memory foam. You may also need to change the cover thickness if you are adding foam inside the mattress instead of on top as a topper. This would lead to a fairly different mattress from the one you have but it may also be worth considering some latex over the memory foam as an option (it creates a more responsive surface and slows down the response of the memory foam underneath and has a different feel which I personally like but others don’t).
I would choose between the options based on clarity about exactly what you want to change and which of the tradeoffs and the different types of fine tuning are most important to you and based on the topper guidelines in post #8 here and the other posts it links to. It would also depend on how confident you are about some of the more “unknown” options you are considering. I would also keep in mind that an extra inch of 8 lb memory foam would be closer in terms of specs than the 2" you are mentioning and if you use a thicker layer than this, especially with 4 lb memory foam, then you are moving into Tempurpedic Cloud territory such as the Tempur Cloud Supreme which uses 2" of 4 lb memory foam over 2" of 5.3 lb memory foam (although yours would have an extra inch of 5 lb memory foam in the second layer which would give you more memory foam to sink into over the course of the night before you reached the firmer support layers so it would have more alignment risk).
So while I can’t tell you what to choose … hopefully this will give you a greater sense of the differences between your options that you can use to “match” to what you want to accomplish and the effect each one may have for both of you.
I’m having trouble diagnosing whether my issue is primary or secondary support. I feel that my butt area is off in alignment, but I would say I have a “bony” butt/hip, so it’d be strange for pure weight being the reason for my alignment problem. Given my ht/wt, would you say the odds are +70% that it’s a secondary support issue? I’ve not had this problem with our old Novaform bed or older spring beds.
I’ll try swapping the “35 ILD” and “30 ILD” layers to experiment in any case.
My wife’s preference is more plushness and I’m hoping that if it’s a secondary support issue I have, we can solve both at once. I think topping with 1" of 8lb Venus would be ideal, but unfortunately no one seems to sell anything less than 2" cuts of Venus these days. An extra 2" may exacerbate my primary support (if that is my main issue), although I suppose I could just remove the 3" of 5lb Sensus layer altogether and put Venus right on polyfoam support layer. That would be my option with the 3" Tempur-pedic topper as well- basically swapping out the 5lb Sensus for something else and trying to return or sell the 5lb Sensus.
My wife heavily prefers memory foam feel over latex, so using latex as a top layer wouldn’t be an option. Since there appears to be no 1" Venus topper, can you recommend another memory foam topper option that might work get more plush than 2" of Venus? I asked Lane and he said the Aerus 4lb is not as soft as the Sensus 5lb, so it’s likely not that. We could also add a softer (all Talalay) layer under the 3" of Sensus, but would that move the needle much?
Bony pelvic areas have less surface area but are still the heaviest part of the body so they may be even more likely to sink in deeper than someone who was “rounder” and had more surface area per lb of weight compressing the foam.
I can’t see you on the mattress or feel what you feel so I wouldn’t even speculate about what the issue may be and I need to leave that to your best judgement along with the insights that the links I provide may give you. It may even be a combination of both (which I would suspect) because your larger size may need both thicker/firmer comfort layers and firmer support layers because they often tend to go hand in hand.
Having a problem on one mattress doesn’t translate into having or not having the same problem on another mattress that has different layering and design. The goal is to sink in evenly in good alignment in all your sleeping positions (see this post which may help you visualize this and provide more information that may help you).
Yes … you are correct that extra thickness/softness would solve both issues. Venus 1" toppers used to be sold at Cymax in 1" layers (and I’m not sure if it was genuine) but they don’t seem to carry it any more. You can find a 1.5" layer here which is the thinnest I found in a quick search. Other 7 - 8 lb memory foams may also work for you if you can find them in a 1" layer.
I would suggest that another 8 lb memory foam would probably also work (assuming that is the best topper choice in your circumstances and only your own experience can know this for sure) but you would need to talk to any suppliers that sold it to see how it compared in terms of its properties. There are also many 4 lb memory foam toppers that feel softer than most 5 lb memory foam and this may also be an issue and with your lighter weight durability of a 4 lb layer probably wouldn’t be an issue but once again you would need to talk with each of the suppliers to find out the specifics of the foam they offer. Different memory foams have a huge variety of different properties. The worst case is that you can experiment with memory foam toppers sold at the big box stores or other suppliers that have a good refund policy which can reduce or eliminate the risk of experimenting.
There really is no formula for me to know how you will experience any layering combination and my role is to help you understand the many influences and risks involved so you can decide on what may be the best choice for you and on your odds of success based on your own experience and insights in combination with conversations with better manufacturers and retailers that can talk to you on the phone.
It’s just not possible for me to make specific design suggestions in other words (outside of the guidelines I link such as the topper suggestions in post #2 here and the posts it links to) because it would take much longer exchanges or individual phone conversations and spending much more time with each member than my current 16 hours a day would possibly allow. My role is to provide more generic advice to help with how to choose rather than what to choose and to help connect you with people with the knowledge and experience that would be are able to help you with specifics that would apply to your particular circumstances (within the limitations of what they have available) rather than be the design consultant for members of the forum.
I wish that it was possible to do more for each forum member and give more specific advice but unfortunately it isn’t.