Grey tide mark behind our youngest’s wardrobe. Shirts a bit clammy, wall colder than the room, that faint mushroomy whiff you pretend isn’t there. External wall. Big lump of furniture tight against it. I didn’t Google. I got a ruler.
Pulled the unit forward. The wall was a couple of degrees down on the rest (cheap IR thermometer) and the air behind it didn’t move at all. Not a “house is doomed” problem. A “we made a micro-fridge” problem.
What I actually did, no drama: slid the wardrobe out 40 mm and kept it there with two little timber spacers at the skirting so it can’t creep back. Stuck rubber feet under the corners to lift it a finger—lets air wash underneath. Popped off the flimsy lower third of the cardboard back to give the void a way to breathe (hole-saw vents would look smarter; this was Tuesday night). Wiped the grey with a damp cloth and basic mould cleaner. Desk fan on low for an hour while it dried. Door left a crack overnight. That’s it.
One week later, same time of day: wall feels like the room, shirts don’t feel like they camped outside, nose says “nothing to see here.” No paint, no liner, no lecture. Just space and a bit of airflow.
Notes so you don’t repeat my nearly-mistakes:
- Don’t eyeball the gap. 30–50 mm works; less and air stalls, more and the room looks weird.
- Don’t tidy boxes under the wardrobe “for storage.” You’ve just blocked the under-wash.
- Don’t dry-scrub the stain. Damp cloth, bag it, bin it.
- Don’t shove the unit back while the wall is still drying. Give it an hour with moving air.
Costs: pads + feet were seven quid. Time: about an hour around spelling homework and a lost pencil argument.
If you want the “why” in plain English (surface temp, RH, dew point), this explainer is good: Energy Saving Trust https://energysavingtrust.org.uk/advice/damp-and-condensation/
If it creeps back (it might in mid-winter), I’ll add a thin insulated liner to that patch of wall after I’m sure the airflow habit is sticking. But honestly, the space did most of the lifting here. It’s the same trick we used behind the living-room bookcase last year—no science fair, just stop building little cold pockets and the house stops sweating in weird places.
Small thing, quick win, zero heroics. Tomorrow I’ll look at the chest of drawers on the same wall. My bet: same problem wearing a different jumper.
