I am looking to add a topper to my new mattress which is in between a firm and a pillow top. It is rated at a 5, from a 1(firm) to 10(soft) scale. We just need a little more cushioning as we are both side sleepers but not too much to where we are not supported by the mattress and its leading to back pain, which we have a history off due to accidents. We are looking at adding a soft (20ILD) natural talalay topper and need recommendations on what thickness to add that would be beneficial for our needs, as we are not looking for a drastic change, I do weigh on the heavy side 290lbs. Will a one inch be a good fit for us? Please let us know what you suggest.
If your mattress is still in good condition and there are no soft spots or sagging (either visible or virtual) then a topper can certainly be a good option to add some additional comfort and pressure relief.
There are many unknowns and variables involved that can affect the type, thickness, and firmness of a topper that will work best for you on your mattress including your body type, sleeping position, your preferences, your sensitivity to different firmness levels, and the specifics of the mattress under the topper (a topper will feel different on different mattresses) so it’s not really possible to predict with certainty which topper would be the best choice for you because each person can be very different.
Having said that … post #2 here and the topper guidelines it links to have more information that can help you use your sleeping experience and along with your familiarity with different materials and other criteria that may be important to you (such as the return policy) as a reference point to help you decide on the type, thickness, and firmness of a topper that will have the best chance of success.
If you are looking for “a little to a fair bit” of additional softness and pressure relief then a 2" topper would be a likely choice “on average”. If you are only looking to change more of the “surface feel” of your mattress and only need “a touch to a little” additional softness then 1" would be the most likely choice. 3" would be more in the range of “a fair bit to a lot” and sounds like more than you would need.
I can’t make any specific suggestions because each person can be very different from others that have a similar body type and sleeping positions and I also don’t know anything about the materials in the mattress that will be under your topper (different mattresses will change how a topper feels) or have any reference points for mattresses that you have slept on and done well with so I would use your own sleeping experience and the topper guidelines I linked to make an initial topper choice (which you may need to exchange) that has good chance of success.
Based on your weight and on “averages” I would tend towards a firmer topper because higher weights tend to sink into materials more deeply than lower weights so they will tend to feel softer than they would to someone that was lighter but that may not be as good a match for your partner (if they are lighter they may need a softer topper) and not everyone fits inside the “averages”. I would also lean towards a 2" topper but your own experience will really be the only way to know whether a specific topper on your mattress is a good match for you.
I would also keep in mind that Dunlop can feel firmer than the same ILD in a Talalay topper (there is more about the differences between Dunlop and Talalay in post #7 here).