About this problem
Where it usually appears
What to look at
When to send photos
Why mould forms behind furniture
Wardrobes, beds and sofas pushed flush against a wall create a small pocket where air barely moves. If that wall is also colder than the rest of the room — common on exterior walls, party walls, or walls behind a headboard on a north-facing side — moisture in the air settles there instead of drying off. Add a room that’s rarely aired and the combination is enough for mould to take hold, usually without anyone noticing until the furniture is moved.
This is a very ordinary pattern in Barcelona flats. Many bedrooms sit against a shared or exterior wall, older buildings often have thinner insulation than newer ones, and a large wardrobe or headboard is exactly the kind of flat, close-fitting surface that traps a still layer of air against a cold wall. None of that means anything is wrong with the flat — it’s simply the spot where the conditions for mould line up most easily.
How far to leave furniture from the wall
A practical, specific answer: leave roughly 5-10 cm — about a hand’s width — between the back of the piece and the wall. That small gap is usually enough to let a little air circulate behind the furniture, which is the main thing missing when mould forms there. It won’t compensate for a genuinely cold, damp room on its own, but combined with airing the room now and then, it removes one of the main conditions mould needs.
Built-in wardrobes and rented flats
Built-in or recessed wardrobes (armarios empotrados) can’t simply be pulled away from the wall, which is part of why they’re a common spot for a musty smell and hidden mould to build up. Leaving the wardrobe doors open for a while each day, and airing the room properly, are the main things a tenant can reasonably do without altering the fitting. If you rent the flat, photographing the mark with a date and telling your landlord or agency in writing is a sensible practical step alongside those small changes.
It’s also worth checking whether the smell or mark is limited to the wardrobe interior or has already reached the wall behind it. A wardrobe that simply needs airing and cleaning is a different situation from a wall that needs treatment before the problem keeps returning to whatever you store inside.
The wall, not the furniture
Our focus is the wall or surface behind the furniture — cleaning it, treating it and repainting where needed. We don’t restore or treat furniture, fabric, mattresses or clothing, and this isn’t a pest-control or extermination service. In most cases, once the wall is properly treated and the furniture sits with a small gap and gets some airflow, the wardrobe or bed itself can simply be cleaned and aired rather than replaced.
Which service may fit
If the mark on the wall is limited and the paint underneath is still sound, anti-mould painting can be enough on its own. If the paint has lifted or the patch is more established, mould removal in Barcelona comes first, with a repaint after. If the same cold-wall pattern shows up elsewhere in the flat, our mould on walls page covers the broader picture, and if it’s tied to condensation on windows too, see condensation mould.
When to send photos
Move the furniture, then photograph the wall behind it — a wide shot showing the wall and where the furniture sits, and a close-up of the mark without flash. A short note on how long the furniture has been there and whether the wall feels cold helps too.
One photo shows the surface condition and helps suggest a sensible option — it cannot name the exact cause of damp or promise the mark won’t return; the cause is fairer to assess on site.
Related pages
With photos and a short note — contact. If it’s already clear the wall needs treatment — mould removal. If the mark has come back after cleaning before, see mould keeps coming back after cleaning.