Mould found when a wardrobe is pulled away from the wall, or behind the back of a sofa, is one of the most common discoveries in a home. It usually appears on an outside wall, in a bedroom, and it is often much heavier than anything visible in the rest of the room.
Why furniture creates the perfect conditions
Mould needs moisture, a surface it can settle on and still air. A large item pushed tight against an external wall provides all three at once.
- the wall behind is already the coldest surface in the room
- the furniture stops warm air reaching it, so it stays colder still
- air cannot circulate in the gap, so moisture is not carried away
- the area is out of sight, so early growth goes unnoticed for months
The result is a small, sealed pocket of cold, still, damp air, which is close to ideal for growth.
Typical signs before you move anything
You do not always have to shift a wardrobe to suspect a problem. Common early signs are:
- a musty smell in the room, often noticed most in the morning
- clothes or bedding stored against that wall smelling damp
- black spotting appearing on the wall just above or beside the furniture
- cardboard boxes or drawer backs feeling soft or cool
- staining on the back panel of a wardrobe or a bed headboard
Treating the area properly
Once the furniture is moved, treat the surface rather than just wiping it.
- Move the item well clear and give the wall time to warm and dry
- Ventilate the room while you work
- Wear suitable protection, particularly for a larger patch in an enclosed space
- Remove the visible growth using a product intended for the surface
- Let the area dry fully before decorating or replacing furniture
- Add a protective finish if the wall is being redecorated
!Mould Solve Mould Eradicator Spray 750ml
For the treatment stage, start with Mould Removal Sprays. For a route that includes protective equipment for a larger patch, compare the Mould Treatment Kits. If the wall is being redecorated, see Mould Prevention & Primers and Anti-Mould Paint.
There is a full step-by-step in how to remove mould from painted walls and ceilings.
Check what the furniture is hiding
While the wall is clear, look at the things that suggest the cause is more than condensation:
- is the plaster damp to the touch or only cold?
- is there staining that spreads rather than sits in spots?
- is skirting or timber soft, blown or lifting?
- is the growth heaviest at the bottom of the wall rather than the top?
- is there any sign of a leak from above, a radiator, or an external defect?
Spotting in the upper corners of a cold wall usually points to condensation. Damp low down, or a spreading tidemark, points to something structural and needs looking at properly. See mould vs damp.
Preventing it coming back
The wall will stay the coldest part of the room, so prevention is about airflow and moisture rather than the wall itself.
- leave a gap of a few centimetres between large furniture and external walls
- avoid stacking boxes tight to the floor against those walls
- keep bedroom doors open during the day where practical
- ventilate bedrooms in the morning, particularly in winter
- avoid drying clothes on radiators in bedrooms
- keep background heating steadier rather than heating in short bursts
- check behind large furniture two or three times a year
Wardrobes on internal walls are far less likely to have this problem, so if the room layout allows it, that is the simplest long-term fix.
What to do about affected belongings
Soft items stored against the wall need their own approach. Surface treatments intended for walls and hard surfaces are not a fabric cleaner, and mould on clothes, bedding or upholstery should be handled separately. There is more in mould on fabric, curtains and mattresses.
FAQs
How big a gap should I leave behind furniture?
Enough for air to move, typically a few centimetres. The exact figure matters less than not having the item pressed flat against the wall.
Should I put insulation board behind the wardrobe?
Anything that changes the wall build-up should be considered properly rather than improvised, because getting it wrong can move the cold point rather than remove it. Treat and ventilate first, and take advice before altering the wall.
The wall is dry now. Do I still need to treat it?
Yes. Visible growth should be dealt with even if the surface has dried, because a dry surface with untreated growth will not stay clean once conditions return.
Why is it worse in the bedroom than anywhere else?
Bedrooms combine overnight moisture from breathing, a door that stays shut, limited ventilation and large furniture against external walls. See condensation mould in bedrooms and bathrooms.
