How do I get a smell out of a room permanently?

A room does not smell; something in it does. The reason smells return is almost always that the source was masked rather than removed, and the source is usually soft and porous.

Safety

What you'll need

• Bicarbonate of soda
• White vinegar
• Enzyme cleaner (optional)
• Carpet cleaner (optional)

Step by step

1. Ventilate first, and note whether it fades.Windows open for an hour. A smell that clears and returns is coming from a material in the room; one that never clears may be coming in from outside or from a cavity.
2. Identify the type of smell.Musty means damp and mould. Sour or ammonia means organic — pets, spills, food. Smoky means tar deposits on every surface. Each needs a different treatment.
3. Check the soft furnishings.Carpet, underlay, curtains, upholstery, cushions, mattress. These hold smells far longer than hard surfaces and are usually the actual source.
4. Use an enzyme cleaner for anything organic.Pet accidents, milk, vomit. Enzyme cleaners break down the compounds rather than covering them, which ordinary detergent does not. It must reach as deep as the spill did — often into the underlay.
5. Use bicarbonate of soda on fabric.Sprinkle generously on carpet and upholstery, leave overnight, vacuum thoroughly. Cheap, effective and it absorbs rather than masks.
6. Wash everything washable.Curtains, cushion covers, throws, bedding. People clean the room and leave the textiles, which is where the smell is living.
7. Wash hard surfaces for smoke.Smoke leaves a tar film on walls, ceilings and inside cupboards. Sugar soap on everything, and expect to seal and repaint — the stain and smell come through ordinary paint.
8. Look for a hidden source if nothing works.Under floorboards, behind an appliance, in a wall cavity, a dead mouse, a blocked drain, or damp. A smell resisting all treatment usually has a source you have not found yet.

Tips

• Bowls of bicarbonate of soda, activated charcoal or coffee grounds absorb ambient smells genuinely, unlike sprays. Leave them a few days.
• If the carpet has been soaked, the underlay almost certainly has too, and it cannot be cleaned in place. Replacing underlay is cheaper than replacing carpet.
• Do not use air freshener while diagnosing. It stops you telling whether the treatment worked.

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