2 Twin XL Mattresses, different heights, looking for foam base layer

My wife and I have different needs so we each ended up getting our own different Twin XL Mattress (each on a twin XL adjustable foundation), that we put together to form a King (with a bed bridge in between). However our mattresses are 2 different heights (mine is 1-2" shorter than hers).

Instead of buying a mattress topper that can substantially alter the feel of the bed, I’m wondering if it’s possible to buy just a 1" or 2" dense foam base layer that I could put underneath my mattress to raise it up so they are the same height without altering the feel of the mattress? I have a Casper Original Hybrid. Something comparable to the 1.8# 36ILD High Grade polyfoam base many manufacturers use as the very bottom layer of their mattresses.

Wondering if anyone has any suggestions besides either getting a mattress topper to put on top of the mattress, or bed risers to lift up the entire adjustable base.

I guess the question is for DIY mattress folks, where do you buy foam materials for the various layers? I’ve read here that FBM isn’t recommended, but have seen Foamonline mentioned as a possibility. Then I know that I can look for either a high quality/density polyfoam, or a firm dunlop latex (such as sleeponlatex or others).

My mattress is Casper Original Hybrid that’s on an adjustable base. Knowing the foundation is solid with no flex, I’m assuming whatever base layer i purchase to place under my mattress I’d want it to be as firm as possible to attempt to not alter the current feel and support of the mattress (just raise it up so it’s level with my wife’s mattress)?

Hi bobby2478.

I think something like this could be a reasonable solution to lifting the bed without compromising the feel of the comfort layer.

I’ll be interested to see what others recommend as well. I know we have a lot of talented and innovative DIYers in the forum who may have great ideas for you.


50.99 if you want to gamble, 50 ild firm-high support: Lux HQ Foam Mattress | Foam Factory, Inc.
125.00 if you want foam, 36 ild, from a different source: Square & Rectangle Foam | FoamOnline

If it were me, I’d probably try the risk, 50 ild at the bottom. Most of the compression wear and tear will be taking place in the top 4 inches.

Thanks. Another question: who else makes “zoned” mattresses and mattress toppers?

I know Flobeds makes their Vzone mattress, and may even sell the comfort layer separately, but they advertise Talalay latex not sure if they offer Dunlop latex as an option. I see Turmerry offers a zoned dunlop latex topper, but it would appear their “firm” is only 27 - 34 ILD which is the same ILD as my Sleep on Latex Medium topper with ILD of 34 (and hips sink in too far).

What i’d really like to do is get a zoned dunlop latex matress topper where it’s more firm/dense under my hips to prevent my hips from sinking in too far, while softer by shoulders to allow my shoulders to sink in.

If you’re already using a 2 inch or thicker topper, you could also zone your hip area by placing a piece of foam directly below the topper(in the center third of the mattress), half an inch thick should do, and around 24 inches by 16. One inch also works, if it’s all you can find, albeit a bit more noticeable. This will effectively firm up the hip area, and be much less expensive than any zoned topper. I estimate it to be equally effective as well, by my own experience. Your mileage may vary however. Good luck.

Just make sure the zoned piece is around 50 ild. How this achieves the desired outcome is by spreading out your weight over a larger area, thus sinking down less. Lake Mattress also sells zoned dunlop layers.

interesting idea, where would i go about finding a dense piece of foam like you suggest (latex or something else)? ideally since i have twin xl i could get something that stretches across the entire mattress (38" wide)

Since it’s only a 0.5" thick layer, and will go underneath a mattress topper just to firm up the middle portion, I went with Foam by mail and their Lux-HQ. Shipping was only $12.99. Looking at Foamonline, they had $19.99 shipping charge plus an additional $9.99 handling fee, which was more than the $21.99 cost of the foam itself. If I were looking for a layer I was actually laying on I’d consider them, but considering the use case I went with the cheaper option since this is just an experiment to see if that can help.

I should note, this is separate experiment from my casper original mattress. Once i figure out what mattress and/or mattress/topper combo works, then if there’s a height difference I’ll consider FBM, Foamonline and any other places where I can buy basic high quality density foam in various sizes/heights so I can add it below my mattress just to raise it up. Any other retailers anyone would suggest to buy polyfoam (high density 1.9lb, high resilience 2.8-3lb) as a base to raise up mattress without altering feel of the sleep surface?