A foam encasement is a border or perimeter of foam which surrounds the coils in the mattress. It is used to hold the coils securely in the mattress.
A foam encasement will help prevent you from rolling off the side of your bed when you get to the edge. A foam encasement can also create a more stable and secure seating edge of the mattress.
When you sit on the edge of the mattress you will not feel the coils and it will provide you with more support. You will also not feel the coils on the side of the bed. Lastly, a foam encasement will help a mattress work with an adjustable bed as it eliminates the need for a wire frame around your coils.
Most coil mattresses that are adjustable bed friendly will have some sort of foam encasement.
For more information on foam encasements in mattresses visit our blog: https://www.nationalmattress.ca/blog/what-is-a-foam-encasement-on-a-mattress