Encasements do effectively seal mattresses and box springs and they are far less expensive than replacing infested mattresses or box springs.
It is important to get an encasement that fits the exact size of the mattress and box spring you have, otherwise there will be creases in the encasement that bed bugs will find useful for harborage.
Don’t get a regular mattress encasement – you must purchase an encasement manufactured specifically for bed bugs.
A bed bug encasement will have very small zipper teeth so the first stage nymph cannot get through the zipper teeth.
There are fewer folds and seems and the encasement has been tested to ensure the bed bugs cannot bite through the encasement.
And lastly, the zipper has a zipper stop so the end of the zipper doesn’t leave an opening.