Foundations, "The Dip", Latex/innerspring...

Hi sheep123,

[quote] My biggest complaint is the “dip” in the mattress which developed a few months after purchase- our body impressions, from shoulders to hips, can be seen through all the comfort layers. I attribute the dip to the lower back pain possibly.

I was surprised to find out what was actually inside our Nordic mattress (the top is zippered and can be opened)- a not too thick wool/cotton top over a 1" piece of latex (the end of the latex has several numbers, including 21.3- ILD maybe?) on top of a 2" layer of “soft” innersprings sitting on top of very firm springs. I looked at the ESW site today, and the Nordic has been redesigned- mine does not have the microcoils, and has one, not two, layers of latex.

Questions: The dip showed up in just a couple of months in the ESW bed and I can’t imagine the latex or the springs wore out in that time! I’ve been moving the adjustable slats adjusters in towards each other- this helps somewhat with the dip, but the bed gets even firmer. At this point, though, almost all the slat adjustments are almost touching in the middle, but still the dip is there. I am wondering if changing the adjustable slat foundation on the ESW bed might eliminate the dip? I talked to ESW about this a couple of years ago, they said a traditional all wood foundation would make the mattress firmer. What about a box spring? Would that make the mattress any softer and possibly remove the dip? I know a box spring isn’t supportive enough for an all foam mattress, but what about my mostly spring mattress with only 1" of latex in it (although the mattress does feel heavy)? A box spring might also eliminate the “division” down the center of the mattress that I can’t sleep on (the beam where the slats on both of our sides meet).[/quote]

The Berkeley Ergonomics mattresses have different names at different stores but your mattress would probably be the same or very similar to one of the current microcoil versions listed here (the 2" layer of soft innersprings are a microcoil) and would probably be the same as the Nordic here.

Any dips you are experiencing will be coming from one of three sources which are either the toppers, the mattress, or the slat system underneath the mattress. The most reliable way to know where any dips are coming from would be through a process of elimination. If you put your mattress on a firm, flat, non flexing surface like the floor the difference between that and having your mattress on the flexible slats (both without the toppers) would tell how much of the impressions are coming from the mattress and how much is coming from the foundation underneath it. The wool in your mattress will compress to some degree over time in the areas that you tend to sleep in most often (and this can be evened out by sleeping in different areas of the mattress) so there will be some slight impressions from this but this should be relatively minor and generally won’t affect the performance of the mattress because wool becomes firmer as it compresses over time unlike foam which becomes softer and develops impressions or soft spots over time.

A non flexing foundation would most likely make your mattress feel firmer because it would have no flex at all. Whether a box spring would make your mattress feel softer or firmer would depend on how the flex in the box spring compares to the flex in the flexible slats you currently have. If the box spring was softer and had more flex it would tend to make your mattress softer and if it was firmer it would make your mattress firmer although how much different people would feel the difference would vary depending on their weight, sensitivity, and sleeping positions. The box spring also wouldn’t be zoned so this would also contribute to any difference you felt as well. The only reliable thing you could predict is that it would likely be “different” and the only way to really know how using a specific box spring would compare to your flexible slats would be to try it.

It’s also not unusual that you would feel the firmness in the center of a flexible slat system where it doesn’t flex when you sleep in the center of your mattress. This would affect people who sleep in the center of their mattress more than people or couples that tend to sleep more on one side or the other.

If it turns out that there is a significant visible impression that is coming from the mattress itself that is more than the warranty exclusion then it’s possible that there is a defect in your mattress and I would contact ESW about this.

The comfort layers of a mattress are almost always the weakest link in the mattress and it’s very common to see pillowtops which use low quality/density foams (which is almost always the case with major brands) soften and/or develop impressions fairly quickly. All the comfort layers of your mattress (the latex and the microcoil) are high quality materials and components so outside of actual defects it’s not likely that they would develop impressions.

Pocket coils are more flexible than the polyfoam in the Casper and would tend to follow any contours in a support system underneath it and be more visible on the surface of the mattress than polyfoam yes. Steel also absorbs less energy than foam as it compresses (the technical term is that they have less hysteresis) so the effect of a flexible support system or any zoning underneath a pocket coil mattress would also tend to be more noticeable than under a foam mattress with a similar thickness. You can see an example of one of the members that purchased a BE mattress with a flexible slat foundation underneath it and replaced the flexible slats with a firm, flat, and non flexing foundation because of the effect of the foundation on the surface of the mattress except in her case the upward bend of the slats was pushing part of her mattress up so it would be the center of her mattress that had a “dip” (see post #50 here).

If I was in your shoes the first step I would take would be to clarify where any dips are coming from and go from there.

If it turns out that your mattress is the issue and the dip is more than the warranty exclusion then I would talk to ESW about a warranty claim.

If it turns out that the dip is in your toppers then they may need to be replaced.

It may also be worth sleeping on your mattress on the floor to see how that affects you (which would approximate the effect of a firm non flexing foundation) and then using toppers (either the ones you have or different ones) to add any additional softness and pressure relief that you may need.

There is more about the different ways that one mattress can “match” another one in post #9 here but since it’s unlikely that you will find another mattress that has exactly the came combination of materials and components (if you even know what they are) … the only way it’s likely that you would be able to find another mattress that had a similar feel and performance to your innerspring mattress would be to try other mattresses that have “somewhat” similar materials and components inside them and then use your own personal experience to decide whether they feel closely comparable to you.

You can see some comments about the Ikea mattresses in post #3 here and the posts it links to.

There is also more about the most important parts of the value of any mattress purchase in post #13 here.

While I can’t speak to how suitable a mattress is for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) because only your own testing and experience can tell you this (see mattress firmness/comfort levels in post #2 here) … outside of PPP, a mattress is only as good as its construction and the quality and durability of the materials inside it so my thoughts about the quality of the materials and the durability of any mattress would depend on the specifics of what was inside it and whether there were any weak links in its design (see this article and the foam quality guidelines it links to) regardless of the name of the manufacturer.