When I have tried the 3" toppers we have, they always raise up on the edges ~ 1-2". It feels like I’m sleeping in a “U”. The fitted sheet doesn’t work well to keep them down, nor does a mattress pad. Is there another way to pin them down on the edges? Right now I’m not able to use them, and it is really frustrating. This doesn’t happen with our 2" or 1" layers.
I am a female side sleeper, ~135lbs, 5’2". The toppers have been cut in the middle to minimize movement transfer from my husband on the other side. The toppers do this whether they are in a cover or bare. Both the 3" dunlop (soft) and 4" talalay (soft) do it.
Is there something I am not thinking of that will keep these down on the edges (particularly the outer edges, inner aren’t really a problem).
This “edge effect” is common to all toppers to different degrees because similar to a pillow top a topper has more freedom of movement and will act more independently and feel softer than the same layer inside a tight fitting mattress cover (see posts #3 and #4 here and this topic). “How much” it happens will vary with the type, thickness, and firmness of the topper, the firmness of the mattress or layers underneath it, and where you sleep on the mattress. With thinner toppers the effect can be less and the mattress protector or sheets you are using may be enough to keep the edges down more effectively.
For some people the edge effect and the additional softness it provides is part of the attraction of a topper vs having the same layer inside the mattress cover but if this bothers you then the only thing I can think of would be using a tighter fitting or less “stretchy” mattress protector or sheets to help keep the edges down more effectively.