Extra firm topper on top of plywood - works great! Density question

About 10 years ago my husband and I started experimenting with ways to continue to use an antique bed that we wanted to keep. He put a 1" sheet of plywood on the frame (it made the box springs unusable which is what we wanted) and made it able to take a queen size mattress. Then we started buying cheap things to put on it. First a futon mattress, then a thicker version of that. Then a 3" foam topper - extra firm. This was the best ever!! He is a side sleeper and I am a side and stomach sleeper. It was about $60 on Amazon and we replaced it after a few years and then increased to a 5" with the same company (Sleep Better). Husband now in 70s and suffered a stroke and other health issues and needed thicker/softer so we now have an 8" coil/foam mattress and I have gone to sleeping on the floor until I can figure out how to firm up my half of the bed. I found a 2"/3 pound density mattress topper and am wondering how that would compare to the 3"/1.5 pound topper that we started with…I just need a very very firm topper to put on a thin piece of plywood, both of which will go on my half of the bed.

Hi kjohnson,

I’m sorry to hear about your husband’s health issues.

Unfortunately, your description of what you’re attempting to accomplish with the layers is a bit confusing to me, so I’m not exactly clear as to what you’re attempting to create.

I’ll work with this last description you provided:

So it sounds like you’re looking to place a thinner piece of foam on top of a piece of plywood. As for comparing the two pieces of foam you mentioned, you didn’t mention what type of foam this was. Is this polyfoam, memory foam, or even latex?

If both pieces are polyfoam, density and ILD/IFD (plushness) are not related, so I wouldn’t be able to tell you how one piece might differ from the other in feel. The higher density polyfoam would be a more durable piece than the lower density piece. I’m guessing that the 1.5 lb piece was probably polyfoam, and ideally I’d recommend 1.8 lb or higher for a polyfoam topper. A 3 lb density is more commonly seen with memory foams or with some of the newer “high performance” polyfoams, many of which are quite plush.

If you can provide me more details on the two foam pieces you’re considering I can hopefully provide more complete answers to your question.

Phoenix

Thanks. You have the concept correct. I am putting an extra firm topper on top of a plywood twin-size board. These are just two that I’m considering; I am open to suggestions for others. Needs to be very dense and firm, not mushy at all.

The 3" topper: 3-inches thick, extra firm conventional foam
100 percent urethane foam;
Provides 1-4/9 pounds density per cubic foot

The 2" topper: 2-inch thick, 100% gel memory foam 3-pound density foam - Unique open-cell technology and gel infused beads work together to regulate sleep temperature and increase ventilation while you sleep

Hi kjohnson,

Thanks for the clarification. I appreciate it.

This would be polyfoam and ideally I’d recommend 1.8 lb density or above (density and durability are related in polyfoam). The ILD/IFD would tell the “hardness” of the foam, with something in the 30s or above usually considered quite “firm” in polyfoam. A polyfoam with a higher compression modulus (high resiliency polyfoam) will also have a very good support factor and feel quite “resilient”.

At 3 lb this would be a more basic memory foam and below the minimum 4 lb density I recommend. But memory foam will not be firm. Memory foam has low resiliency (not springy) and would be more “mushy” as you described – not at all what you had mentioned you’d like.

A higher density polyfoam or a firmer latex (perhaps Dunlop over Talalay as it has a higher compression modulus – firms up faster), would be two good areas for you to pursue. While not a complete list, there are some various topper vendors listed in the component post here that might be helpful to you.

Phoenix