FORENSIC DIAGNOSTIC PLATES

HHSRS CATEGORY 2 HAZARD — DAMP AND MOULD GROWTH (HOUSING ACT 2004, SECTION 9). WARM MOIST AIR FROM OCCUPANCY (COOKING, BATHING, DRYING) CIRCULATES TOWARD THE COLDEST SURFACE. WHERE THE WALL SURFACE TEMPERATURE (12.4°C) FALLS BELOW THE DEW POINT (15.6°C AT 21°C / 72% RH), WATER VAPOUR CONDENSES TO LIQUID. THIS IS A THERMODYNAMIC CERTAINTY, NOT A LIFESTYLE ISSUE. INADEQUATE VENTILATION IS THE PRIMARY CONTROLLABLE FACTOR. PRESCRIBED REMEDIATION: CONTINUOUS MECHANICAL EXTRACT VENTILATION (MEV) TO BUILDING REGULATIONS APPROVED DOCUMENT F, PLUS INTERNAL WALL INSULATION (IWI) TO BS 6576:2005.

HHSRS CATEGORY 2 HAZARD — DAMP AND MOULD GROWTH (HOUSING ACT 2004, SECTION 9). CODE 4 LEAD FLASHING HAS FATIGUED AT WELT JOINTS AFTER 80+ YEARS OF THERMAL CYCLING. WATER INGRESS TRACKS THROUGH THE FAILED JUNCTION INTO THE CAVITY WHERE MORTAR DROPPINGS BRIDGE THE GAP, CONDUCTING MOISTURE TO THE INNER SKIN. PROTIMETER SURVEY CONFIRMS MOISTURE GRADIENT: 24.6% WME AT CORNICE LEVEL REDUCING TO 16.1% WME AT DADO RAIL. INTERNAL PLASTER EXHIBITS TIDE-MARKED SALT STAINING WITH EFFLORESCENCE. PRESCRIBED REMEDIATION: STRIP AND RELAY CODE 5 LEAD TO BS 6915:2001 WITH MINIMUM 150MM UPSTAND AND CAVITY CLEARANCE.

CONCEALED INTERSTITIAL DECAY FROM A MICRO-FRACTURE AT THE SHOWER TRAY WASTE SEAL. SLOW WATER INGRESS ONTO TIMBER FLOOR JOISTS HAS PROGRESSED TO WET ROT — CONIOPHORA PUTEANA IDENTIFIED. PROTIMETER READING: 28% MC (ABOVE 20% DECAY THRESHOLD). SUPPORTING NOGGINS AND FLOORBOARDS SHOW MOISTURE WICKING PATTERNS. THE CEILING BELOW EXHIBITS THE FIRST VISIBLE SYMPTOM: A SPREADING DAMP STAIN. THIS DEFECT IS TYPICALLY CONCEALED FOR 12–24 MONTHS BEFORE OCCUPANT AWARENESS. PRESCRIBED REMEDIATION: STRIP OUT AFFECTED TIMBERS, TREAT SURROUNDING JOISTS WITH BORON-BASED PRESERVATIVE, REPLACE WITH TANALISED C24 TIMBER TO BS 5268, AND INSTALL COMPLIANT TANKING BENEATH THE REPLACEMENT SHOWER TRAY.

RISING DAMP IS MOISTURE DRAWN UPWARD THROUGH MASONRY BY CAPILLARY ACTION. THE DPC (DAMP PROOF COURSE) IS EITHER ABSENT, BRIDGED BY EXTERNAL GROUND LEVELS, OR HAS DETERIORATED. PROTIMETER READINGS SHOW A CLASSIC DECLINING MOISTURE GRADIENT: 24.6% WME AT BASE REDUCING TO 14.2% WME AT 1M HEIGHT. HYGROSCOPIC SALTS (CHLORIDES AND NITRATES) CRYSTALLISE AT THE EVAPORATION FRONT, FORMING A VISIBLE SALT BAND. CONTAMINATED GYPSUM PLASTER MUST BE REMOVED AND REPLACED WITH RENOVATING PLASTER TO BS EN 998-1. PRESCRIBED REMEDIATION: CHEMICAL DPC INJECTION TO BS 6576:2005 OR PHYSICAL DPC INSERTION WITH MINIMUM 150MM EXTERNAL GROUND LEVEL REDUCTION.

ASPERGILLUS NIGER COLONISATION AT THE WALL-CEILING JUNCTION WHERE A THERMAL BRIDGE PERMITS COLD BRIDGING. THE EXTERNAL WALL SURFACE TEMPERATURE DROPS TO 11.2°C — BELOW THE DEW POINT OF 14.8°C AT 21°C / 68% RH. PERSISTENT RELATIVE HUMIDITY ABOVE 70% AT THE WALL SURFACE ENABLES SPORE GERMINATION WITHIN 48–72 HOURS. THIS IS NOT LIFESTYLE CONDENSATION BUT A STRUCTURAL THERMAL DEFICIENCY. PRESCRIBED REMEDIATION: THERMAL BRIDGE DETAILING WITH INSULATED PLASTERBOARD TO ELIMINATE THE COLD SPOT, COMBINED WITH IMPROVED VENTILATION PROVISION TO BUILDING REGULATIONS APPROVED DOCUMENT F.