Hi Daroopers1937,
You are making a risky purchase with your Signature Sleep mattress because the foam layers on either side of the spring are a very low quality/density material (1.25 lb polyfoam) that could compromise the durability and useful life of your mattress/topper combination.
You can see my comments about choosing a firmer mattress first with the intention of adding a softer topper later (where you can’t test the combination in person) in post #2 here.
In most cases I would avoid this approach because of the uncertainty involved with making two purchase choices instead of only one and choosing a topper that would be suitable in terms of thickness, firmness, and PPP for a specific person on a specific mattress can sometimes be almost as difficult as choosing a mattress that doesn’t need a topper in the first place. I would generally focus on choosing a mattress that is likely to be a suitable match without a topper (unless you can test the combination in person or you are purchasing both online as a “set” that is designed to work together and they both have a good return/exchange policy) and then use the option to add a topper as a “backup” strategy in case your initial choice is too firm and doesn’t turn out as well as you hoped for rather than a “primary” strategy.
It can also be more costly than just buying a mattress which includes the same materials as the topper as a layer inside the mattress itself (vs having a separate topper) and you would be avoiding the risk of having additional materials in your base mattress that you may not need or that may be lower quality foam that can soften or break down more quickly or that may be softer than what would be ideal for a transition layer under a softer topper.
Having said that … the topper you purchased is certainly a very high quality and durable material.
I’m not sure if you are clear about the difference between a box spring and a foundation. A box spring has springs inside it that flex under the mattress and because they are an “active” part of the design of a sleeping system (mattress and box spring) they can have a significant effect on the comfort, support, and the durability of some two sided mattresses (particularly if the mattress has “linked” springs). On the other hand … there are very few one sided mattresses today that are designed to use a box spring as a support system and in many cases they will invalidate a mattress warranty for a one sided mattress which generally do best with a foundation that has minimal to no flex (vs a box spring that flexes) or a platform bed which also has little to no flex under the mattress. There are many in the industry that mix up the terminology between box springs and foundations even though they are very different products.
In most cases a two sided mattress that has linked springs (such as Bonnell, Offset, or Continuous coils) will do best with an actual box spring with springs inside it that is designed for use with the mattress to provide some additional deep support for the mattress and to act as a shock absorber to prevent damage to the springs. The top of the box spring should have some padding to even out the support of the springs in the box spring and protect the softer foam on each side of the mattress from the springs in the box spring. In some cases a two sided pocket coil mattress would be OK with a foundation (that has no springs inside it) because the pocket coils are less susceptible to damage from shock but I would also make sure that the foundation was padded to protect the softer foam on each side of the pocket coils as well. In general though I would follow the specific suggestions of the mattress manufacturer about the type of support system that would be most suitable for one of their two sided mattresses and that would meet their warranty criteria because not all manufacturers have the same criteria. A good padded box spring would also cost more than your mattress.
In general yes. Having said that … you can see Signature Sleep’s suggestions here and I would probably use their suggestions or something similar (perhaps with smaller spaces in between the wire grid) with a mattress that is in such a very low budget range and that is likely to break down fairly quickly with any foundation and it probably wouldn’t be worth using a more costly foundation.
A Bed Rug or even a layer of firmer polyfoam on top of a wire grid foundation such as the one they suggest would help to provide a more even support surface and help prevent the softer foam layers on the bottom of the mattress from sagging into the wire grid or gaps between any slats which could break down the foam layers more rapidly and cause impressions in your mattress but once again I’m not sure that the additional cost would be worth it for such a low budget mattress that probably won’t have a particularly long comfort life anyway.
Any foundation that is used under most of the mainstream pocket coil mattresses that are sold at most mattress stores would probably be fine as well since most of them have smaller spaces between the wires or slats than the Signature Sleep foundation that they suggest for their mattresses.
Phoenix