Clean the gap, mask the edges, then run a neat, flexible bead of caulk or silicone to stop draughts and dust.
SK-01Clear the room and check the gapMove furniture, rugs and boxes away from the skirting so you can work along the whole run without stopping. Look closely at the gap — is it even, or wider in places? Note what flooring sits against it: carpet, laminate, wood or tile, as this decides which sealant you need next.
SK-02Choose the right sealant for the floor typeFor living rooms and bedrooms, use a flexible decorator's caulk — it's paintable and blends into the skirting colour. In kitchens, bathrooms or anywhere damp, use silicone sealant instead, since caulk isn't waterproof. Where skirting sits above carpet, push sealant gently into the carpet edge rather than trying to bridge an open gap.
SK-03Clean the gap thoroughlyVacuum along the whole gap to lift out dust, grit and pet hair. Use a stiff brush or an old flat screwdriver to scrape out any flaking old paint or caulk. Wipe with a damp cloth and let it dry fully — sealant won't grip a damp or dusty gap.
SK-04Fill wide gaps with backer rod firstIf the gap is wider than 5mm, don't try to fill it with sealant alone — it will crack and pull away as the house moves. Push a length of foam backer rod into the gap first, so only a thin bead of sealant sits on top. This also stretches your sealant further on long runs.
SK-05Mask the edgesRun a strip of masking tape along the floor and another along the bottom edge of the skirting, leaving only the gap itself exposed. This gives you a crisp, straight line and stops smears on the floor or paintwork. Take your time here — a neat mask line makes the finished job look far better.
SK-06Apply the sealantCut the cartridge nozzle at a 45° angle to roughly match the gap width, then load it into a caulk gun. Run a steady, continuous bead along the gap in one pass, keeping the gun moving at an even speed. Try not to stop and start halfway along a wall — the join always shows.
SK-07Smooth the beadWet your finger with a little water (for caulk) or use a plastic sealant smoothing tool, and run it along the bead in one smooth stroke. This pushes the sealant into the gap and leaves a neat, slightly concave finish. Wipe excess onto a cloth as you go, not onto the skirting or floor.
SK-08Remove the masking tape straight awayPeel off both strips of tape immediately, before the sealant starts to skin over. Pull the tape back on itself at a low angle rather than straight up, so you don't drag the fresh bead. Wait too long and the tape will tear the sealant away with it, leaving a ragged edge.
SK-09Leave to cure and tidy upLeave the sealant undisturbed for the time stated on the cartridge — usually 24 hours for a full cure, though it's touch-dry much sooner. Avoid vacuuming right along the skirting or moving furniture back until then. Wipe down your tools and bin the empty cartridge and used tape.
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