A problem I had with ZONING my mattress
Feb 23, 2008 10:08 PM
Location: L.A. area
Joined: Jan 18, 2008
Points: 1161
As most of you know I have been experimenting with my mattress which basically consists of, top to bottom, top 1/3 zone to middle 1/3 zone:

TOP 1/3 of mattress (shoulder area)
1" soft PU foam
1" medium HR foam
2" soft visco foam
springs

MIDDLE 1/3 of mattress (hip area)
1" soft PU foam
1" medium HR foam
1" very firm HR foam
1/2" super firm HR foam
springs

This is my current configuration which seems to work pretty well so far, though I'm still experimenting.

But at first the zones I had made were killing my back and I figured out why:

On the next to top layer, under the soft pu layer, I had different densities of foam so there was a line right at my waist which was the division between, say, a medium one
inch layer and a firm one inch layer. So that "line" where the medium piece met the firm piece was actually creating a pressure point or line of pressure all the way across
my waist, or above my waist (25" down from the top of the mattress).

What I realized is that I HAVE to have the same density of foam on that top layer (next to top layer, not counting the topper, it's the top layer). Otherwise I was getting a line of pressure across my waist from the difference in densities. I assume I also need to have the topper be an even firmness all the way down the length of the mattress.)

So once I began using Medium firmness or medium ILD for that next-to-top layer for both my top 1/3 and the middle 1/3 of my mattress, that pressure line disappeared and
now I am doing much better! I still have a much softer top 1/3 for my neck area, however, by making the layers UNDER the top layers be much softer for my shoulders.

This may not be true for everyone, but it was certainly true for me!

Hope this might help someone who is zoning. I'm curious if anyone else has ever run into this problem.

Re: A problem I had with ZONING my mattress
Reply #16 Mar 2, 2008 10:50 PM
Location: L.A. area
Joined: Jan 18, 2008
Points: 1161
kimmcgov wrote:
If you are at your wits end, you might just want to try a self inflating Thermarest pad underneath one or two layers of latex. This has been the best solution we have tried so far. You can get one at REI where they have several different models to choose from. The XL size is 30 inches wide and they come in different thicknesses. You can tweak the firmness during the night by adding or letting out a little air. As I said in another thread, they are the equivalent of a poor man's Sleep by Numbers...

These things aren't cheap, but unlike most inflatable mattresses, they are bomb-proof. And the great thing about getting one from REI is that you can return it at any time for any reason...



Hi, which thickness of the Thermarest are you using?

We do have one of these but it's very narrow and not too thick - just used for camping. I think our's is way too narrow to use even for my twin bed. 30" wide might work. Too bad they don't make them 37" wide! Then we'd really have something we could play with in our modular mattresses!

As to tweaking them in the night, are you using it right on top, below your sheet or what? If I put it under my topper(s) and fitted sheet I sure wouldn't want to get up in the middle of the night and re-make my mattress - take off the sheets, get down under the topper(s) and add or release air... But it would work as another "topper layer" in my mattress, perhaps the next layer from the top, under some latex or soft PU foam.

Re: A problem I had with ZONING my mattress
Reply #17 Mar 3, 2008 6:18 AM
Joined: Sep 7, 2007
Points: 476
kimmcgov wrote:
Cloud9, what weight is your visco foam, do you know? Is it 5llb? And how is it holding up being only 1 inch thick? Did you try other materials (HR foam, latex?) before deciding on the memory foam?


The 1" memory foam is some cheap stuff from Overstock.com. I think it was $39 any size. I  have no idea what the density is. Could be 3 lb, could even be less, it doesn't feel like the 2" 4lb topper I have. The reason I ordered it was because I missed the cradling sensation of my 2" topper but that one made my new mattress, which already has 4 or 5 inches of built in foam, way too soft for me. The 1" offers just a bit of cushiness without going too soft. It also has the added benefit of sleeping much cooler than the 2" 4lb visco. It seems to be holding up just fine. I haven't noticed it getting soft where my butt's been lying on it, but it's only about 7 months old. In any case, at $39 I'm not too concerned. If I have to replace it in a year or two no big deal.

Have I tried other materials? Oh yeah! Lots of them. Fiber pads, eggcrates. I also have one of those Brylane toppers which I'm keeping for when I reconstruct my mattress. And then there's carpeting and HR foam and a flat feather pillow.... It's very complicated. Overall I like the feeling of memory foam best. It has this nice cradling feeling. Talalay just feels jiggly and unstable to me. PU foam is too mushy. I like HR foam for it's firm supportive qualities. But back to memory foam. I'm not really crazy about 5lb visco. It's too temperature sensitive and too slow to recover. In general I've found the lower the density the cooler the foam sleeps and the faster the recovery. This makes it behave more like conventional foam so you don't find yourself rolling back into a ditch.

I know there are some new visco foams out there that are supposed to be ventilated to sleep cooler and some higher density foams that sleep firmer, but I like memory foam primarily as a soft top layer over firmer support materials.

Re: A problem I had with ZONING my mattress
Reply #18 Mar 3, 2008 12:25 PM
Joined: Sep 11, 2007
Points: 111
jimsocal wrote:
Hi, which thickness of the Thermarest are you using?

As to tweaking them in the night, are you using it right on top, below your sheet or what?

The ones we have are a couple of inches think (maybe 1.75 inches) and 27 inches wide. We have them on top of the mattress with the 1 inch latex topper and fleece wool topper over them. If you put the nozzle at the top and on the outside and leave your sheet loose there so you can pull it up and let out a little air if you need to in the night. To add air you'll need to get out of bed. It will only take a night or two to dial it in, then you are good to go and can tuck the sheet back in.

Even though the pads combined are less than the width of our Queen size bed, with the latex and wool pad on top, it just looks like the normal crowning you get on a plush, non-pillowtop mattress.

I do want to get something else that will replicate the firmness of the Thermarest as having a nozzle on the bed seems a little weird, but we are sleeping great on this set up -- better than we have in months.
Re: A problem I had with ZONING my mattress
Reply #19 Mar 3, 2008 12:32 PM
Joined: Sep 11, 2007
Points: 111
cloud9 wrote:
The 1" offers just a bit of cushiness without going too soft. It also has the added benefit of sleeping much cooler than the 2" 4lb visco.

Maybe we should try a 1 inch piece of visco. 2 inches was not working as we ended up in a hole by morning with aching backs.
Re: A problem I had with ZONING my mattress
Reply #20 Mar 4, 2008 5:54 AM
Joined: Sep 7, 2007
Points: 476
kimmcgov wrote:
Maybe we should try a 1 inch piece of visco. 2 inches was not working as we ended up in a hole by morning with aching backs.

That won't happen with the 1", but it is a very soft foam, so it you're trying to firm your mattress up a bit this will just take you in the opposite direction.

Re: A problem I had with ZONING my mattress
Reply #21 Mar 7, 2008 12:39 AM
Location: L.A. area
Joined: Jan 18, 2008
Points: 1161
kimmcgov wrote:
Maybe we should try a 1 inch piece of visco. 2 inches was not working as we ended up in a hole by morning with aching backs.


I too would like to try a 1" to 1-and-1/2" visco foam topper, maybe a 3lb one. At first I thought I wanted to try the 5lb but then I slept on my 2" 4lb one and realized it was too hard for me. A 1" 4lb might work but I think if I buy one I'll buy a 3lb one. I do have a 3/4" 3lb one but it isn't quite thick enough and it's really more like 1/2" because it's convoluted.

I love the feeling of memory foam but what I found is that often it feels good the first few nights and then softens up too much. Maybe if it's just a thiin topper for softness, though, that is not an issue. It was surely an issue with the 3" stuff I was trying and even the 2" one: Not enough support, too much sinking in.

Re: A problem I had with ZONING my mattress
Reply #22 Mar 7, 2008 5:24 AM
Joined: Sep 7, 2007
Points: 476
jimsocal wrote:
I too would like to try a 1" to 1-and-1/2" visco foam topper, maybe a 3lb one. At first I thought I wanted to try the 5lb but then I slept on my 2" 4lb one and realized it was too hard for me. A 1" 4lb might work but I think if I buy one I'll buy a 3lb one. I do have a 3/4" 3lb one but it isn't quite thick enough and it's really more like 1/2" because it's convoluted.

I love the feeling of memory foam but what I found is that often it feels good the first few nights and then softens up too much. Maybe if it's just a thiin topper for softness, though, that is not an issue. It was surely an issue with the 3" stuff I was trying and even the 2" one: Not enough support, too much sinking in.


Jim, you might like the 1" visco from Overstock.com. I've had it on my bed since July and it still feels the same way it did when I bought it. Maybe because it isn't very thick, but just enough to give the bed a little bit of soft cushiness. It runs a bit on the skimpy side so get it bigger and cut it down if you can. I love the feeling of memory foam too, but 3" would be too much of a good thing for me. With just one inch lack of support isn't an issue because you don't sink in enough for it to become one.
This message was modified Mar 7, 2008 by cloud9

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