I have a custom King mattress made with 100% natural latex (Earthfoam), no springs. It is 30cm in total, consisting of a 10cm 85 density base layer, 10cm 75 density mid layer and 10cm 65 density comfort layer. The mattress sits on a solid timber slat frame which is 100% flat.
We’ve had the mattress for around 4 months and we’ve noticed a hump in the middle - it feels like the middle is twice as firm as the sides we sleep on. When you lay in the middle, you feel like you are going to roll off to either side. The hump isn’t too visible, but it feels very apparent when you lay in the middle.
I know natural latex takes time to settle and will soften over time, and the best way to evenly wear is to keep rotating 90 degrees. We have done this for over a month, however it doesn’t seem to have helped soften the middle. I’ve also tried sleeping by myself in the middle, as uncomfortable as it is, I’ve slept around 30-40 nights in the middle by myself and the hump doesn’t seem to have flattened at all.
The 3 mattress layers aren’t bonded together, so they can be removed. I did some testing and took the 65 density comfort layer off and placed it on the floor. When you lay on it you feel the exact same hump as when the mattress is assembled - firm in the middle and softer on the sides.
The middle of the mattress is basically unable to be slept on, as you feel you’ll roll off onto either side. Is there anything that can be done to resolve this? Thanks!
First, I recommend checking your king foundations/frame to ensure they are completely level and flat. When you have a split king layered mattress with a hump down the middle, the most common cause is uneven foundations where they meet in the center. If the foundations are slightly raised where they join, this can create a hump in your mattress because latex foam contours closely to the surface it’s on. Even a small elevation at the center of your twin-long foundations can lead to a noticeable hump in the mattress.
To test if the foundation is the issue, remove the mattress from the foundation and place it directly on the floor. If the hump disappears, then the foundation is the culprit. A simple solution is to place a 3/4" plywood sheet over the entire foundation, effectively turning it into a platform foundation.
Thanks for the reply. Mattress is not split - single cores all the way through.
Foundation is 100% flat as I mentioned in my post, this is confirmed with a spirit level. The slats are that strong that a single slat can support me with zero flex if I stand on one, and I’m 80kg.
Mattress has been tested on the floor, the hump is still there. As I also mentioned in my post, I tested the top 10cm D65 comfort layer separately by itself on the floor, and the hump/middle firmness is there, so it seems to be isolated to the top comfort layer. It feels like there’s a piece of 2 by 4 timber underneath the top layer running down the middle.
It must be the angle or optical illusion, but the slats looked warped down where you would have depressions in the mattress. Slats 4 and 5 from screen left to right.
I am also surprised that since the slats go head to foot there was not 3 cross beams. Upper, middle, and lower with cross beam support legs.
Perhaps they felt the wood would be supporting with just one center cross beam.
Sorry the pictures may be a little misleading as the mattress is currently rotated 90 degrees in an attempt to even out the wear. The slats run across from left to right, and the support beam runs through the middle from head to toe, with 3 legs supporting the beam. The slats are completely flat without any warping, it must be an illusion or iPhone camera trickery.
Hopefully one of the latex experts can chime in with some feedback
If you put the top layer of latex on the floor and the problem was still there, then really all you can do is replace that layer and this will hopefully fix the issue for you.
If you slept on the middle of the layer for some time, I don’t think it would flatten out completely, it seems like you’d have a couple of smaller hills and valleys in the layer.
