🔍 Basement “Leak”, Rising Damp or Sneaky Condensation? 💧🧱 | Damp Ring EXPOSED!

00:00 Intro – architect-designed basement flat & “bunker” cupboards 00:36 Suspicious damp ring one foot above slab 01:08 Plasterboard construction & hollow-sounding wall 01:46 Gap under MDF skirting; mild swelling observed 02:28 Possible moisture sources: penetration, leak, condensation 02:55 Thermal-imaging reveals cold base of wall 03:13 Opening the wall – cavity-membrane inspection (no water) 04:03 Exposed pipework shows past condensation (green corrosion) 04:40 Remedy ideas: cut plasterboard, fan + dehumidifier 05:10 Separate ground-floor damp patch & failed tanking 05:38 Brown staining in other bunkers – interstitial condensation 06:11 Upstairs: insufficient floor expansion gap 06:30 Ground-floor wall damp – likely roof ingress 06:45 Render & planter defects letting rain track in 08:12 Main-supply leak test – negative 08:38 Neighbouring pub’s historic leaks ruled out 09:06 Kitchen ventilation: noisy 23 L/s fan rarely used 10:00 Bathroom fan only 3 L/s (needs 15 L/s) 10:22 Data-logger demo & dew-point explanation 11:59 Summer ventilation still inadequate 12:16 Recommend two dehumidifiers (bunker + kitchen) 13:36 Mould threshold: 85 % RH for long periods 13:52 Summary – condensation, not penetration, is prime culprit 14:30 Thank-you & next steps 🧾 CONCLUSION Your lower-ground damp is multi-factorial: • Condensation / excess vapour in the unheated cupboard mimics a leak. Cold incoming mains pipes and an uninsulated solid floor let moisture condense; plasterboard that touches the slab then “wicks” it upward, producing tide-marks. • Possible services leak (softener/filter circuit) cannot be ruled out, but no active flow was detected during testing. On the ground floor • Penetrating damp is seeping through the back wall where cracked felt/render and a plant-pot junction allow rain to track down and bypass the tanking. Brown staining confirms water migration through masonry. • Penetrating damp in the centre is under a cracked bitumen felt roof. ⸻ ✅ ACTION LIST Lower-ground floor 1. Cut and raise plasterboard – remove skirting, trim boards 10 mm clear of the slab, reinstall skirting. 2. Insulate all cold pipes in the basement cupboard to reduce surface condensation. 3. Lower indoor vapour load – cook with lids on, simmer not boil, use the kitchen extractor fan and close the kitchen door. 4. Also upgrade extraction – ideally fit a true 60 L/s kitchen fan or consider installing a bathroom style continuous floor extractor fan - running background at a 5 l/s with a boost function to 15 l/s when humid (set to 65%RH). 5. Add a 20 L/day dehumidifier in the basement cupboard; aim to keep dew point below outside air year-round. 6. Position a second 20 L/day dehumidifier in the open-plan kitchen during cooking sessions to mop up excess vapour whenever the extractor alone cannot maintain dew-point control. 7. Measure dampness in wall with Dr Meter or similar Moisture meter. Continue data-logging – use https://damp.ai/detect Ground floor 1. Repair external defects – replace the tired felt roof or overlay with EPDM/GRP (Glass Reinforced Plastic) or Bitumen Felt. 2. Improve drainage falls – ensure the rear balcony/flat roof sheds water away, eliminating ponding. 3. Fill hairline render cracks and reseal around the soil-pipe and planter collar. Consider replacing Planter, isolated from the wall. Floor 1. Relieve floor expansion – lift skirting beside the raised board, multi-tool a 8–10 mm expansion gap, then refix.