Find and fix a leaking gutter, then dry out and redecorate the damp patch it left on your wall.
DG-01Confirm the gutter is the causeWatch the wall during or just after rain. A damp patch that follows a vertical or diagonal line down from roof height, often worse near a gutter joint or downpipe, points to a leaking gutter rather than rising damp or a plumbing leak. Check inside first, then go outside and look up at the gutter from the ground before you get a ladder out.
DG-02Set up the ladder safelyUse a stable ladder on firm, level ground, angled correctly, and have someone foot it if you can. Take a bucket, gutter scoop, gloves and a rag up with you so you don't need to keep climbing down. Only go as high as you need to see the gutter clearly.
DG-03Clear the gutterScoop out leaves, moss and silt with a gutter scoop or old trowel, working towards the downpipe. Bag the waste as you go rather than dropping it, so it doesn't block the downpipe below. A blocked gutter is one of the most common causes of overflow and damp patches, so this step alone sometimes solves the problem.
DG-04Test the gutter with waterPour water from a bucket, or run a hose, into the highest point of the gutter and watch its whole length. Look for drips at joints, water running behind the gutter rather than into it, or overflow where the gutter has sagged. Mark any leak point with a bit of tape or chalk so you can find it again once the gutter is dry.
DG-05Repair the leakFor a leaking joint, clean and dry the area, then apply gutter sealant along the seam. For a cracked union or split bracket, unscrew and replace it with a matching part, using stainless steel self-tapping screws into the fascia board. If the gutter has sagged, tighten or add a bracket to support it properly.
DG-06Re-test and check the fallRun the water test again from step DG-04 to check the repair holds. While you're up there, check the gutter has a gentle slope towards the downpipe rather than sitting level or falling the wrong way, as this causes overflow even with no other fault. A slight, even fall is enough — you don't need to measure it precisely.
DG-07Let the wall dry outOnce the gutter is fixed, the wall needs time to dry before you decorate over it. Brick and plaster dry slowly, often a few weeks depending on how wet it got and the weather. Keep the room ventilated, open a window when you can, and use a dehumidifier if the room is enclosed. Don't paint or fill over a patch that's still damp to the touch — a damp meter will show a falling reading over several days.
DG-08Make good the damp patchOnce the wall is dry, scrape off any flaking or blistered paint back to sound plaster. Fill any cracks or small holes left behind with a multi-purpose filler, let it go off, then sand it flush and wipe away the dust with a damp cloth.
DG-09Prime and redecorateOld water staining can bleed through ordinary paint, so apply a stain-block primer over the repaired area first and let it dry fully. Once dry, paint or paper to match the rest of the wall, blending the edges so the patch doesn't stand out.
DG-10Tidy up and keep gutters clearDispose of gutter debris with your green waste and clean your tools. Make a habit of clearing gutters at least twice a year, especially after autumn leaf fall, so the same leak doesn't come back somewhere else along the run.
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