Wash walls with sugar soap

Clean walls thoroughly with sugar soap to remove grease and dirt before painting, working top to bottom and rinsing well.

WS-01Clear and protect the roomMove furniture away from the walls or right out of the room if you can. Lay dust sheets over the floor and skirting boards, taping them down along the wall base so drips don't run underneath. Take down pictures, curtains and any loose fittings.

2 each · Dust sheets

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1 roll · Masking tape

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WS-02Remove loose dust and cobwebsBefore any water goes near the wall, brush off loose dust, cobwebs and flaking bits with a soft-bristle brush or a vacuum with a brush attachment. Pay attention to corners, coving and the top of the skirting. This stops you smearing dry dirt into wet grime later.

1 each · Soft brush or vacuum brush attachment

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WS-03Mix the sugar soap solutionFollow the ratio on the packet — most are one capful of sugar soap to around 4-5 litres of warm water. Mix it in a bucket rather than the sink where you can, as it's a fairly strong degreaser. Put on rubber gloves before you start, and open a window for ventilation.

1 bottle · Sugar soap (concentrate or powder)

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2 each · Bucket

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1 pair · Rubber gloves

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WS-04Adjust your approach for the wall typeOn solid brick or block walls (usually under a painted plaster skim) you can wash fairly firmly with a well-wrung sponge. On plasterboard — whether on timber studs, metal studs, or dot-and-dab — keep the sponge just damp, not dripping, since soaking the paper facing can soften it and cause bubbling. On lath and plaster, common in pre-1930s houses, use the lightest touch and the least water possible: heavy wetting or pressing can crack the plaster keys behind the laths.

WS-05Wash the walls top to bottomWork in sections about 1m wide, starting at ceiling height and working down to the skirting. Wring the sponge or cloth out well before each wipe so you're not flooding the wall. Rinse the sponge in the second bucket of clean water regularly to stop you just moving dirt around.

3 each · Sponge or cleaning cloths

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WS-06Rinse off the residueGo back over each section with a fresh cloth and clean water only, to lift off any leftover sugar soap. Any residue left on the wall can stop new paint or wallpaper adhering properly, so this step matters even though it feels repetitive.

WS-07Let the walls dry fullyLeave the room to dry naturally with a window open if the weather allows. This usually takes a few hours, longer in a cold or poorly ventilated room. Don't start painting or filling until the wall feels completely dry to the touch.

WS-08Clean upRinse buckets and sponges under a tap and pour any leftover sugar soap solution down an outside drain or toilet, not onto the garden or into a sink you use for food. Fold up and remove the dust sheets once everything is dry, and pop windows open for a while longer to clear any lingering smell.

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