So, how to make a memory foam mattress firm? I am 5'-4, 150 pounds and my husband is 6'-3, 240 pounds we are both side sleepers. My husband has had back surgery some time in the past. We purchased a Sealy Optimum Radiance gel memory foam mattress. Although my husband had no problems with it, I found this bed too soft for me and it gave me a lot of lower back pain. I trying to find out if there's some kind of a latex topper that could add a bit of firmness to the bed. I called the retailers and asked if I could add a 1" medium firm topper. They said they would not advise the firm topper, except if it is to be placed under the bed. OTOH a 2" topper would make the bed too high for me to climb on to. Another thing, will it help if I add a sheet of plywood instead? BTW, I think the boxsprings are wire frame in a fabric wrapping. Any helpful ideas are most welcome.