Hi Napper,
Semi Flex boxes last longer than regular wood foundations and are not prone to the creaks and groans that develop in the regular wood foundations. However when used with some heavier king mattress you could experience a ridge form down the middle where the two meet in the middle. There is no give in the seam which can cause this ridge when used with heavier king mattresses.
Like many things, the devil is in the details, so it all depends upon the quality and style of semi-flex foundations being compared to the specific style of wood foundations. A good quality wood foundation with appropriate center support an 3” or less between slats will generally be quite a bit “sturdier” than a good quality semi-flex foundation. A wood foundation that is commonly used under an innerspring mattress with only 7-8 cross slats and a felt or cardboard deck on top of those slats would not be as strong generally as a good semi-flex foundation. Both styles of foundations can creak over time, as this is dependent upon use, type of frame used, humidity changes, use of a cardboard deck (in a wood foundation), and quality of assembly.
Are the last 2 sentences referring to 2 seperate pieces being used for the king size? Is that what they mean when they say where the 2 meet in the middle and there is no give in the seam? If so, would a coir mattress rug eliminate that?
Yes, you are correct. This is in reference to two twin extra long foundations used for a king mattress. In a semi-flex unit, over time the modules can take a bit of a set in the middle area of the foundation, but along the edges, with the thicker gauge border rod and different support elements, it might not take the same “set”, resulting in a surface that will in effect be higher in the middle.
A local manufacturer sells and recommends them with their foam beds and even substitutes the semi flex with the Pure Talalay Bliss mattress because they say the semi flex is better than the foundation that comes with the Pure Talalay Bliss.
Just for clarification, Pure Talalay Bliss does not supply or manufacture foundations for their mattresses. There is a company called Ironwood that they recommend, who has the covering to match their mattresses, and they make a wood platform foundation that would work with a latex mattress.
Regarding foundation selection for their mattresses, from Pure Talalay Bliss:
Important Foundation Information: Pure Talalay Bliss mattresses are substantial in weight, and are designed to work on a solid, firm surface, not spring foundations or bases that are structurally not capable of supporting the weight of the pruchaser’s Pure Talalay Bliss mattress. Pure Talalay Bliss may require purchaser to provide proof of the quality of the foundation, adjustable base, or bed frame used in conjunction with the mattress if purchaser makes a claim under this Limited Warranty. Therefore, if purchaser uses inappropriate foundations, box springs, adjustable bases, or inferior frames with the mattress, such use will void this limited warranty without limitation. **An appropriate bed frame must completely support the foundation as well. Foundations must have an appropriate bed frame, that at a minimum meet criteria above.
While they do not explicitly describe the exact type of foundation to be used, I would have a concern with a semi-flex foundation under a heavy latex mattress over time and the potential for it to take a set and possibly cause sagging in the mattress and also potentially void any warranties.
The site that I copied and pasted this from recommends heavy duty wood foundations for king size mattresses. I find the foundation to be a difficult choice because some of the wood slat ones having inconsistent quality and the better ones costing several hundred dollars plus shipping. Not into the DIY.
The DIY wood foundations are usually quite simple to assembly, but if you’re not into that then I understand. Your other options would be to find a local retailer carrying a heavier-duty style of already-assembled foundation, or pursue another design. The DIY foundations will not be of a “finished” quality, as they are generally covered with some sort of a fabric coverlet.
I just don't like the idea of the wire or metal frames that some companies are selling and/or recommending for their mattresses when it will be used for a foam mattress. That being said,
maybe using a coir rug on one of these could eliminate my concerns although one mattress manufacturer that sells these did say that they can be a little noisy with a lot of movement.
Using a coir bed rug on top of a semi-flex can help minimize the “cheese slicer” effect of the wire network “pushing into” the foam base over time, but it won’t change the potential for the gradual sinking in that can occur in the semi-flex modules. A coir bed rug placed atop a finished semi-flex foundation with a non-skid covering should be quite quiet, as it doesn’t tend to move. If placed atop a metal platform bed with an exposed grid network, I could see the potential, at least initially for some sliding.
Phoenix
