Hi JackBauer,
[quote]First I believe KD (knock down) foundations may have their place - but now for heavier mattresses like my 13" thick latex - UNLESS you have a bed / frame that provides support in the right locations.
So with the one wooden support running down the center only getting support at the single cross bar point in the very middle of the mattress, there seems to be a LOT of deflecting going on. So I need to do something.[/quote]
I would certainly agree with the need for a suitable bedframe because anything in between the mattress and the floor and the load distribution of the system can contribute to sagging. The KD foundation itself though wouldn’t likely be the issue and it’s stronger than most of the foundations that are sold with other latex mattresses that in some cases are even thicker and heavier. They are made specifically to SleepEz’s specifications to make sure that the gaps in between the slats are less than 3" (which is less than most competing foundations). Of course there are even stronger foundations yet that use stronger wood or constructions or smaller gaps that would be stronger yet but in most cases they wouldn’t be necessary.
Depending on your weight … I would doubt that the foundation itself is the issue or that it is contributing to a “lot” of sagging. It would be interesting to calculate the deflection of the foundation itself using the software mentioned in this thread but of course that would require more specialized knowledge and software and as you mentioned it would also depend on what was underneath it. You could also test the foundation directly on the floor to see how much of a difference it makes which would give you a better sense of how much of the deflection is the result of your bedframe or how it supports the foundation.
I would also tend to use heavy duty steel bedframes that have at least two center legs to the floor with heavier mattresses or with higher body weights. The Knickerbocker Monster is a good example of one of these but there are also some other examples mentioned in post #10 here that also have a center support that runs the length of the frame.
Most bedframes are intentionally made shorter than the foundation for safety reasons. Some of the bedframes (with a center support that runs the length of the bed) mentioned in the last link are longer though and can be used with a footboard (one example made by Leggett & Platt is here). Perhaps one of these will give you the best of all options (a strong frame with good center support and the ability to attach a footboard).
Phoenix