It is two in the morning and something is running about above your bed. The noise stops when you switch the light on, then starts again. In a detached house, under a converted loft or on the top floor of an apartment building, this happens every winter: rodents look for warmth and find it in the insulation, just above your living space.
The good news is that a scratching ceiling is not something you have to live with, and you can usually work out fairly quickly what you are dealing with. The less good news is that a rodent settled in an enclosed void does not leave on its own: it finds shelter there, nesting material and often a direct route to the kitchen through the service ducts.
This article is written for you at home first, then for shops and offices with suspended ceilings, where the same problem hides above the tiles.
Who is making that noise above you?
The noise alone is not enough, but together with the visible signs it points the diagnosis in the right direction. These are the cues we use during an inspection.
| Sign | House mouse | Rat (black or brown) | Other suspect to rule out |
|---|---|---|---|
| Noise | Quick, light pattering, faint scratching | Heavier steps, objects moved, loud gnawing | Stone marten: clear racket, heavy running early in the night |
| Timing | All night, sometimes during quiet daytime hours | Mostly early and late in the night | Birds: early morning, near the eaves |
| Droppings | 3 to 6 mm, thin, scattered along runs | 1 to 2 cm, thicker, often in groups | Marten: twisted droppings, sometimes with hair |
| Tracks | Small tunnels dug in the insulation | Flattened runs in the insulation, greasy marks on beams | Feathers, twigs carried in |
The edible dormouse, often blamed, generally hibernates from October to April: a regular noise in the middle of winter is therefore more likely to come from a mouse or a rat.
Why lofts are so attractive to rodents
For a rodent, a loft is the perfect shelter. Heat from the home rises and stays trapped under the roof. Glass wool, rock wool or cellulose wadding make bedding that only needs digging into. Nobody goes up there, there is little light, and electrical conduits or ventilation ducts offer just as many routes down to the floors below.
The damage goes beyond the nuisance:
- compressed insulation soiled with urine and droppings loses part of its performance;
- gnawed cables can cause short circuits and faults that are hard to trace;
- urine and droppings can carry diseases, such as leptospirosis in the case of rats;
- smells eventually drift down into the rooms, especially if an animal dies in an unreachable void.
What you can check yourself without taking risks
Before you call, a few simple observations make the diagnosis quicker. Be careful: an unboarded loft is not made for walking.
- Only step on the joists or on boarding, never on the insulation between two beams: the ceiling below would not hold you.
- Protect yourself: gloves, an FFP2 mask and a head torch. Do not sweep droppings dry, as this lifts dust into the air.
- Look from the hatch: droppings on the frame, insulation dug out or flattened, chewed pieces of conduit, a smell of ammonia.
- Try the powder test: dust a little flour or talc on the edge of the hatch and come back the next day. Fine footprints or a tail mark confirm traffic.
- Listen at a fixed time for two or three nights and note exactly where the noise comes from: it often shows where the nest is.
These notes will help the technician, whose inspection will also look for how the rodents get in: a displaced roof tile, an unscreened vent, a cable entry in the façade, a shared service riser in an apartment building.
Suspended ceilings in offices and shops
In business premises, the suspended ceiling plays the role of the loft. The space between the tiles and the structure, the ceiling void, carries cables, air-conditioning ducts and cable trays that connect a whole floor. A mouse can travel from one end of the floor to the other without ever touching the ground.
Signs that should catch your attention:
- droppings found when a tile is lifted during maintenance;
- a stained or slightly sagging tile with no identified water leak;
- gnawing on network cables or flexible ducts;
- droppings near the kitchenette, break areas or bins.
For a food business or a restaurant, rodents above a preparation area are a hygiene issue to deal with straight away. In every case, tell the building manager or the syndic (the managing agent of a French co-owned building) if common areas are involved: treating one unit while the rest of the building stays open rarely gives a lasting result.
The Sentinel Protocol applied to lofts
When we work under a roof or in a suspended ceiling, we follow the four steps of the Sentinel Protocol, in this order.
- Inspect: record the signs in the void and in the rooms below, identify the species, locate the outside entry points and the internal routes (ducts, risers, boxing).
- Treat: install secured bait stations, fixed and numbered, or snap traps depending on the situation. Never loose bait in the insulation.
- Sanitise: seal the entry points with materials rodents cannot get through (steel wool, mortar, metal mesh), advise on which soiled insulation to remove and, if needed, carry out a premises disinfection.
- Follow up: a follow-up visit as set out in the protocol, a photo report emailed the same day, and active vigilance on your side thanks to the observation points we show you.
Sealing the entry points before treating means locking the rodents inside the ceiling. They then gnaw a new way out, sometimes into the living space.
The mistakes we come across most often
- Throwing sachets of rat poison into the insulation: the animal dies out of reach and the smell lingers for weeks.
- Relying on an ultrasonic repeller: it deals neither with the rodents already there nor with the entry points.
- Waiting for spring: a mouse can have several litters a year, and a quiet, warm nest grows all winter long.
Calling in a technician
Our Certibiocide-certified technicians work in your home as well as in your premises, in Paris and across the Île-de-France region. Depending on the species identified, the job falls under our house mouse or brown rat treatment, both part of our rodent control service. To learn more about the animal, read our mouse guide or our brown rat guide. The price is shown on the pricing page and paid online when you book your slot. For an apartment building or business premises, our annual contracts include regular visits.
FAQ
How can I tell whether the noise in my ceiling is a mouse or a rat?
Listen to the kind of noise and look for droppings. A mouse makes light pattering sounds and leaves scattered droppings of 3 to 6 mm; a rat has heavier steps and leaves droppings of one to two centimetres. The technician confirms the species during the inspection.
Does loft insulation need replacing after rodents have been in it?
Not always. Insulation that has only been dug into in places can stay after treatment. Insulation that is heavily compressed, soaked with urine or full of droppings loses its performance and can hold smells: it is better to remove it wearing protection, then sanitise before re-insulating.
Can rat poison be put straight into a suspended ceiling?
It is not advisable. Loose bait can be moved, contaminate other surfaces and cause the animal to die somewhere unreachable, with lasting smells. Baits must be placed in secured stations that are fixed and monitored, which is what a professional treatment provides.
To see this topic in the light of public data (ANSES, Santé publique France, MNHN), read our sourced pest statistics.
