Mattress encasement size Full XL

I had gotten some allergy/dust might Allersoft Mattress and Boxspring cotten encasements in size Full. I had later decided to get a mattress in size Full XL. But Allersoft doesn’t make encasements in size Full XL.

Anyone know of any that make allergy/dust might encasements in size Full XL.

I do have a 5 sided waterproof mattress cover I plan on getting to put on top as they offer it in Full XL.

Hi jasonsmith,

I took a quick look and like you I didn’t find any non membrane encasements in full XL sizes. There are some that use a membrane but these would be less breathable. If you don’t find any that fit the full XL then you may need to use a queen instead.


Hi Phoenix,

Maybe I’m missing something here, but wouldn’t a 5-sided waterproof mattress cover placed on top of an allergy/dust mite encasement make the encasement unnecessary because the cover would already be allergy/dust mite proof?

On a separate note, I’d like to take this opportunity to put in a good word for the Full-XL bed, which is the width of a full and the length of a queen. This very useful bed size (IMO) has been largely ignored in the current marketplace. A few decades back, before the rise of the California King, the Full-XL was much more common. What its current state of obscurity means, unfortunately, is that even if a consumer is able to locate a Full-XL mattress that is suitable for them, it may then become a pain in the butt to find accessories that will fit it (which is how this thread got started).

Uh no. The part I didn’t mention is these encasements are also bed bug proof as well. So an encasement usually not only stops allergy/dust mite, but also stops bed bugs incase you were to bring one home.

Hi Bedimpediment,

5 sided mattress protectors only protect the top surface of the mattress.

A mattress encasement that is designed to help with allergies and dust mites will protect against dust mites on all 6 sides. They are meant to be semi permanent and remain around the mattress for the long term. If you choose an allergy encasement that is breathable (which is the ideal) then it wouldn’t be waterproof or water resistant and you would still need a mattress protector for the top surface of your mattress to protect against the fluids we release each night or accidents and which can be removed and cleaned more easily and on a more regular basis to keep your sleeping surface in a cleaner and more hygienic condition without having to remove the allergy encasement.

If you choose an allergy encasement that has a semi breathable waterproof membrane on all sides then you wouldn’t need a separate 5 sided waterproof or water resistant mattress protector since it would already be waterproof but it may still be a good idea to add a non waterproof protector for the top surface that can be more easily removed and cleaned. Membrane types of mattress encasements are much less breathable and you would have a more permanent “semi breathable” layer all around your mattress so for allergies I would lean towards a more breathable encasement with an additional water resistant or waterproof protector for the top sleeping surface.

In the case of a mattress encasement that is meant to protect either you or the mattress against bed bugs (along with dust mites) then they are normally the membrane type with a special zipper that keeps the bed bugs either in or out of the mattress and these are also meant to remain on the mattress permanently. This would allow less airflow through the mattress but it’s can be one of the tradeoffs involved in fully protecting a mattress against bedbugs or protecting you from any bedbugs that are already inside the mattress. In this case since they already provide 6 sided protection against liquids then you may wish to only add a non waterproof protector for the top surface that can be removed and cleaned on a more regular basis since the bed bug protector would already protect against liquids.

There is more about mattress encasements (either for allergies or bed bugs or both) in post #2 here.

Your certainly right that Full XL seems to be a dying breed.


The 5-sided waterproof cover I have is Omniguard Advance. I have the Full size, but they offer it in Full XL as well.

They also have a 6-sided version. So I may just look at getting the 6 sided version and not bother with the cotton encasement underneath. As the Omniguard Advance should be both waterproof and bedbug proof as well. Main reason I was looking at 6-sided cotton bed bug cover and 5 sided waterproof cover on top was so I could easily remove the waterproof cover to wash. But with a 6-sided waterproof version may could just do a water/soap wipe down as that would be too much of a pain trying to remove every time I wash my sheets.

I haven’t looked to see if they also offer one for the boxspring in Full XL. Mainly just wanting bug bed proof for boxspring. But if they don’t, then could look at the Allersoft Queen encasement for the boxspring. As since the boxspring won’t be moved, then could just tuck the excess under and probably won’t have any problems with the excess popping out.

Is there a list of good quality mattress covers and encasements available? As I know there is alot of junk out there.

Hi jasonsmmith,

Post #2 here has more information about mattress encasements and also has a link to another forum site that is probably the most authoritative that I know of about specific encasements that protect against bed bugs.