Do bed bug mattress encasements work?

A mattress encasement is one of the few bed bug products that specialists themselves recommend. It is also one of the most misunderstood. It will not get rid of bed bugs on its own, and a cheap one can do almost nothing. Used properly, it saves the mattress and makes the rest of the treatment easier to check.

What an encasement is

An encasement is a fitted cover that zips right round a mattress, enclosing all six sides. It is not the same as a mattress protector, which only covers the top and sides and is held on with elastic. For bed bugs only a full encasement helps, because the bugs live in the seams, piping and labels around the edges and underneath.

What it does

An encasement does two jobs:

• It traps what is inside. Bugs and eggs in the mattress cannot get out to feed. Adults can survive a long time without a meal, so the cover has to stay on for many months; the usual advice is at least a year.
• It removes hiding places. A smooth cover with no seams gives new bugs nowhere to settle on the mattress. Any that do appear are easy to see and deal with.

It also protects a new or expensive mattress after treatment, so you do not have to throw it away.

What it does not do

It does nothing for the bed base, headboard, skirting, sofa or carpet edge, which is where many bed bugs are. If the rest of the room is not treated, bugs keep biting and simply live elsewhere. That is why an encasement goes on as part of a professional treatment rather than as a fix in its own right.

Choosing one that actually works

Look for these points rather than the marketing on the box:

• A zip all round with a zip stop or lock at the end, so the zip cannot creep open. Bed bug nymphs are small enough to fit through a gap of a millimetre.
• Fine, tightly woven or laminated fabric that bugs cannot bite through or squeeze into.
• The right depth. Measure the mattress, including any topper. A cover that is too tight tears; one that is too loose folds over and creates new hiding places.
• A pale colour, which makes spots and bugs much easier to see.

Covers for divan bases and box springs are worth fitting too, since the base is often where most of the bugs are.

Protectors, covers and encasements compared

Shops use these names loosely, so it helps to know what each really is:

• Mattress protector: a fitted sheet-style cover, often waterproof, held on with elastic. It covers the top and sides only. It does nothing for bed bugs, because the seams and underside stay open.
• Zipped mattress cover: encloses the mattress but may use an ordinary zip with no stop, or a fabric loose enough for small nymphs to get through. Better than a protector, but not reliable.
• Bed bug encasement: six-sided, with a fine zip that closes into a stop or lock, and fabric tested against bed bugs. This is the one specialists mean.

If the packaging does not say the cover is designed and tested for bed bugs, assume it is not.

Divans, box springs and bed bases

In many UK homes the mattress sits on a fabric divan base. The underside of a divan, with its dust cover and staples, is one of the commonest places to find bed bugs, often more than the mattress itself. A mattress encasement on its own leaves that untouched.

Specialists usually treat the divan, and may suggest a separate encasement for it. Slatted wooden and metal frames are easier: the joints and screw holes are treated directly, and there is no fabric for bugs to hide in. If you are replacing a bed after an infestation, a simple metal or wooden frame is much easier to inspect and keep clear than a divan.

Will an encasement stop bites on its own?

No. If the bugs are also in the bed base, the headboard or the skirting, they keep feeding at night. People sometimes fit an encasement, see fewer bugs on the mattress and assume the problem has gone, while it carries on spreading in the rest of the room. Use one alongside treatment, and keep checking for new signs.

When to fit it

Ask the specialist. Usually the mattress is treated first, then the encasement goes on straight away, on the same visit or the same day. Fit it carefully, without dragging it across the floor, and check the zip is fully closed at the stop. In typical Bristol prices, an encasement fitted as part of a treatment adds about £25 to £55 a bed.

Looking after it

Leave it on for at least a year, and check it every time you change the sheets for rips, holes and an open zip. Patch any small tear with strong tape straight away, or replace the cover. Wash the bedding over it at 60°C as normal, as the NHS advises for bedding during an infestation.

The rest of the treatment

An encasement is a useful part of the job, not the job itself. A specialist treats the bed base, furniture and room, by spray course or heat, and checks that nothing is left. Our Bristol price list shows typical costs for both, and you can book a visit for a fixed price.