Hi sAfuRos,
[quote] I was thinking either:
(a) buy a thin boxspring/slatted frame with a cover (expensive)
(b) put a thin piece of plywood over the whole bottom as one large base (cheap but flimsy?)
(c) putting a thin foam mattress under the addable, like the Ikea Moshult: Products - IKEA
For reference, if you scroll through the pics, you can see the slats/rods in question on Amazon here:
www.amazon.com/LexMod-Fabric-Platform-Frame-Queen/dp/B00PFNAWV4
Let me know what you think! Much appreciated. [/quote]
I would share your concern about support surfaces that have a smaller surface area under the mattress. While they may be OK over the short term or even the medium term with a mattress that has a firmer polyfoam support core … it could certainly be an issue over the longer term with the mattress sagging into the gaps between the wires.
Option “a” would work but as you mentioned would be unnecessarily costly.
Option “b” would also work but there would be no ventilation under the mattress which can be more risky in some environments or situations (see post #10 here)
Option “c” would be too soft and would have too much of an effect on the feel and performance of the mattress (a foam mattress does best with a firm non flexing support surface underneath it).
There are some relatively low cost suggestions in the last part of post #10 here that IMO would be better than any of the options you mentioned.
Phoenix