need help about memory foam for a hide abed

We bought a 4.5" memory foam for our sofa that came with air mattress. It barely closes with the 4.5" - We bought a memory foam mattress specifically for sofa beds that folds more easily. We ordered it from Wayfair. Look for the one with the picture of a sofa bed. $170. We also bought a twin size bed board from Vermont Country Store to put under the mattress to make it more firm and when the mattress is folded up we put the "board" under the sofa cushions to give it support for sitting. Our air mattress had springs that helped the sofa support, we needed the board. The board is covered in vinyl. You may need 2 twin boards when the bed is extended.

If your air mattress is not firm enough, perhaps adding more air (inflating to a higher pressure) will help... We have an air/foam mattress on our "hide-a-bed" in the bus, and we can "adjust" to some degree the firmness by the amount of inflation

It was difficult to follow your post with lack of punctuation, but I think you said you need either 8 1/2 or 6" foam. I would be concerned that a memory foam won't compress enough to fold to the size of your bed when stowed. May depend on the weight of the foam.

Bed in a box is a good supplier.

If your air mattress is inside a nice zipped up cover and has a bit of a topper you can pull the air part out and restuff with a temperfoam topper. We use a three inch one. It works very well.

I think I would buy a cheap mattress then put a memory foam topper on it.

We have found that the foam is hot in summer. I believe they make a 'Cool' foam now if that interests you. Good luck!

Memory foam comes in various weights which give varying amounts of support or give as you lay on it. Basically you can buy firm or soft memory foam. You need to figure out what you want before you just buy some generic type foam.

Go to Walmart or Sams Club and get one, then cut to length if necessary. We have two memory foam layers on our RV bed for a total of about 6-7 inched. over a plywood bed surface. Sleeps very well.