Hi Annmarie,
If I had a mattress and was in a similar situation, there are a few things I might do. Phoenix already posted a link to a mattress surgery in progress, with some instructions there too. URL is here:
https://forum.mattressunderground.com/t/fix-or-replace-worn-out-simmons-mattress
Phoenix also has a great DIY post with various materials, including mattress cases which will be important if you want to put it all into a new mattress case. The URL is here:
https://forum.mattressunderground.com/t/foam-factory-any-good
Overall, if I had decided to do mattress surgery, these are some rough steps I’d follow.
-
Determine how I’d plan close it all back up in the end. Be it buy a new mattress case and put everything into it or somehow try to save the existing mattress case. If you decide to get a new mattress case, i might be inclined not to order it until you get a bit further into the surgery so you know how thick of one you want to get based on measuring the current depths of the springs and estimating extra materials.
-
Open it up in such a way as I could continue using the mattress while in progress, to determine what’s there and thicknesses desired/required.
-
Determine what layers were already there. You might opt to keep your layering the same, or take portions from his side and use on your side. I.e. You might reuse some of the material, especially if the materials are good and have been working for you. Post pictures here for advice and review.
Phoenix is the expert behind this … Mostly the point of the above is to let you and he, and those of us that might comment, see what you’re working with/from without making the bed unsleepable, because this will be a process.
-
Like you said, I’d leave the final layer before the springs the same, and if you relocate everything into a new mattress case I’d probably keep any bottom layers under the springs too.
-
Determine how many and type of layering he and or you will need / want and try these layers. You really should be evaluating the layering for PPP, which is where DIY mattressing can become more expensive and time consuming, because you won’t really know if the layers are right until you try them. Many outlets won’t let you return used layers. You might reuse some of the layers from the existing mattress, especially on your side, since it seemed to be working for you and assuming they’re high quality.
-
Put it all back together and enjoy
As you noted, a standard king means you can easily get twinxl sized pieces and side by side they add up to the same size.