Bed bug treatment explained: steam, residual spray and heat, and how many visits it takes

Professional bed bug treatment in the UK starts with a survey, then combines methods rather than relying on one: dry steam and a residual insecticide for most flats, whole-room heat for some sealed whole-property jobs, with desiccant dusts, monitors and encasements in support. The UK codes of practice call for at least two visits, spaced around the time eggs take to hatch, because no spray reliably kills eggs. Pest Stop uses dry steam plus residual treatment over follow-up visits, with a written six-month guarantee, subject to the site survey.

Why does a survey come before any quote?

Because the quote has to describe a plan. The BPCA Code of Best Practice states that a full on-site survey is essential before a reliable quotation; that if no evidence is found, pesticides must not be used and monitoring offered instead; and that the quotation must set out which rooms will be treated, how many visits may be needed, what happens if control is not achieved after the last quoted visit and, where heat is mentioned, whether that means genuine heat treatment or a steam generator.

The survey also fixes the scope: if access to any room is refused, the code says the technician must make clear that control cannot be assured, which matters in shared flats and HMOs. Ours is free, and the fixed price that follows is for the rooms and visits written down.

How many visits does bed bug treatment take?

A minimum of two, and the gap between them is set by biology rather than convenience. Eggs hatch in roughly 10 to 20 days at room temperature and resist insecticides better than nymphs and adults do, so the European code of practice recommends a second treatment after about two weeks, longer in a cold property, to catch what hatched after the first visit. The BPCA code puts it as a minimum of two visits, with intervals that reflect the insect's biology.

Councils work the same way: Lambeth treats in two visits three weeks apart and every Wandsworth bed bug treatment involves two visits. A heavy or long-standing infestation may take three, each with the written treatment report the BPCA code requires on every visit.

What does dry steam do, and what does it not do?

Dry steam kills every life stage, including eggs, wherever the nozzle touches. The European code recommends commercial dry-steam units and warns that the temperature falls away within a few centimetres of the nozzle, so it is drawn slowly along mattress seams, frame joints, the inside of a divan base, headboards and skirting boards, avoiding brush heads that flick eggs away.

Its limit is reach: steam cannot get inside a wall void or down a cable run, so the code says that unless the infestation is light, control cannot reliably be achieved with steam alone, and it should be one part of an integrated plan. Dead bugs are vacuumed up afterwards and the room is aired, because steam raises humidity.

What does a residual insecticide do, and why does resistance matter?

A residual insecticide, applied to cracks, crevices and the structure of the bed, keeps killing bugs that cross it for weeks after the visit. Every product must be approved under UK biocide rules and carry an HSE or authorisation number on its label, and is applied to label, with the room clear for the stated time, usually two to three hours. Clothing is never treated, and mattresses only with products approved for that use.

Resistance is why this cannot be the whole job. The European code records widespread resistance in UK bed bugs to pyrethroids and carbamates and notes that where one treatment used to be enough, several are now routine; the NHS tells the public that bed bugs may resist some insecticides. The BPCA code therefore highly recommends multiple active ingredients: in practice, rotating actives from different classes, adding an insect growth regulator, and using desiccant dusts such as diatomaceous earth or silica, a class to which no resistance has ever been reported, in sockets and voids where a water-based spray must not go.

When is whole-room heat the right call?

Heat is the single-visit option for a property that can be sealed. Bed bugs and their eggs die quickly above 45°C to 48°C, so heaters and fans hold the whole room above that point, with probes in the cold spots; the European code says eight to twelve hours is typical for a hotel room and that heat sources should stay below 58°C to 60°C to avoid damage. It works regardless of resistance, and the BPCA code limits it to experienced operators.

It is not the right call for most London flats. The code warns that bugs become extremely active as the temperature climbs and try to escape, so every route into the flat next door, the floor above and the void below has to be blocked, which is rarely possible in a converted Victorian terrace or a mansion block. Heat-sensitive belongings have to go out, and even heat firms schedule a follow-up inspection two to three weeks later. Our standard treatment for a flat with neighbours is dry steam into the harbourages plus a residual treatment over two or more visits, the approach that matches the codes and that we guarantee.

What about freezing, encasements, monitors and sniffer dogs?

Each has a place, and none replaces the methods above. Carbon dioxide snow or dry ice freezes bugs and eggs on contact without damaging property, but the code notes limited independent research on the equipment, that chilled bugs can appear dead and later recover, and that cold cannot penetrate items.

A mattress encasement only stops the mattress being infested; a bed base encasement is worth more, because bugs inside a divan are notoriously difficult to treat. Chemically impregnated covers are not encasements and are not endorsed, as most populations already resist the pyrethroids they contain. Interceptor cups under the bed legs, with the bed pulled off the wall and bedding off the floor, cut bugs off from their food and double as monitors, an approach the Bed Bug Foundation recommends for multi-occupancy buildings. Scent detection dogs can screen many hotel rooms quickly, but the code is clear they are an aid to visual confirmation and never the sole justification for treatment.

Is bed bug fumigation available in the UK?

Not as a standard domestic service. The word is used loosely to mean spraying, and the foggers sold for home use cannot reach the harbourages and tend to spread the infestation instead. If a firm offers to fumigate your flat, ask what the product is and whether its label covers bed bugs.

Why do bed bug treatments fail?

Almost always for one of four reasons, none of them bad luck. Harbourages were missed, usually a divan base, the back of a headboard, under skirting or behind a socket, because the survey was rushed or a room was off limits.

There was no second visit, so eggs laid before the first treatment hatched a fortnight later. Bugs came back in from an adjoining flat, a suitcase or a work bag. Or a DIY spray scattered them into the walls before the professional arrived.

That is why the European code says a written warranty should be conditional on the customer's cooperation, ongoing housekeeping and the risk of re-introduction where adjoining units cannot be inspected. Our six-month written guarantee is subject to the site survey for the same reasons, and the survey is where we tell you if a neighbour's flat is the real source.

What to do next

If you are still at the "is it bed bugs?" stage, read our guide to the signs of bed bugs in a London flat first. If you have found evidence, call Pest Stop Control on 020 3411 2329, Monday to Saturday 8am to 7pm, for a free inspection survey, often the same day. Our bed bug treatment page covers the method and the guarantee; for guest rooms and multi-room sites see hotel pest control, or send us the details online.