Foam, fabric, moisture
A mattress is not rigid, and that is exactly the problem
Foam has memory in the literal sense. Viscoelastic foam recovers from a normal squeeze in minutes, which is why a mattress-in-a-box survives compression. What it does not shrug off is a sharp fold held for a long stretch. Rolled loosely along its length and released within a couple of hours, foam comes back. Creased hard over the edge of a folded seat back for a two hour errand run, and the cell structure at that edge can stay permanently soft. You will feel it as a valley under your hip in about a month, and there is no fixing it after the fact. Innerspring is a different failure mode entirely. Bend an innerspring past a shallow curve and the coils and the border wire deform, and coils do not spring back from being kinked. That is why our rule is simple: mattresses ride flat, or they ride upright against a wall with support down the whole length, never folded into a shape a car dictated.
Box springs are the opposite problem, and it is the one that catches people. A box spring is a rigid wood or steel frame. It cannot flex at all. A standard queen box spring is 60 by 80 inches, and that 80 inch rigid dimension is what fails at a stairwell turn or a tight L hallway. The mattress will bend around that corner. The box spring physically will not, and no amount of pushing changes a wood frame. If you have a narrow stairwell, the answer is a split box spring, two 30 by 80 halves that each turn a corner easily, and it is worth knowing that before delivery day rather than during it. Then there is Florida. A mattress is porous fabric over a foam or fiber core, so it acts like a sponge for road grit and for water. A mattress bag is a $10 piece of plastic that keeps out both, and it also stops the bare fabric from sliding against a van wall for twenty miles, which is how you get a scuffed and dirty top panel before the thing has ever been slept on. Bagged, flat, strapped over blankets, enclosed. That is the whole method and it is not complicated, it is just not optional.
- Memory foam gets a bag and rides flat or fully supported upright. It never gets folded, because a hard crease held for hours can stay soft permanently.
- Innerspring coils and the border wire deform when bent past a shallow curve, and they do not recover. Flat only.
- A queen box spring is a rigid 60 by 80 frame. It does not bend around a stair turn. A split box spring, two 30 by 80 halves, does.
- Mattress bag on every single one, every time. Road grit and Gulf afternoon rain both wick straight into a foam core and stay there.
- It rides in the enclosed van or the enclosed 13 foot trailer. Nothing ever rides on an open bed, in any weather, including the nice weather.