flat-roofing

15 articles

• Cold Flat Roof Problems: Why Cold Deck Roofs Fail, Interstitial Condensation and Converting to Warm Deck
  Why cold deck roofs fail: interstitial condensation, 1:150 ventilation requirement rarely achievable, timber rot progression, blistering diagnosis, conversion to warm deck options
• EPDM Rubber Roofing Guide: Bonded vs Mechanically Fixed, Seam Tape, Termination Bars and Drainage Falls
  EPDM bonded vs mechanically fixed: seam tape (75mm min overlap, EPDM primer then butyl tape), termination bars at ≤200mm centres, 150mm upstands, 1:40 recommended fall
• Flat Roof Building Regs Part C: Weather Resistance, Flat Roof Upstands, Flashings and Surface Water Run-Off
  Part C weather resistance: 150mm minimum upstands, lead/aluminium flashings with 75mm overlap and 25mm chase, drainage falls, penetration detailing, NFRC CoP compliance satisfies Part C
• Flat Roof Building Regs Part L: U-Values, Insulation Thickness Options and Thermal Bridging Details
  Part L 2021 U-value target 0.18 W/m²K: 130–150mm PIR or 175–210mm EPS, tapered insulation average U-value calculation, thermal bridging at parapets (ψ values)
• Flat Roof Drainage Design: Falls to Outlets, Gutters vs Internal Outlets, Overflow Provision and BS EN 12056
  BS EN 12056-3 design rainfall (75mm/hr primary, 150mm/hr overflow), minimum falls 1:80, mandatory overflow provision, outlet sizing by roof area, green roof drainage considerations
• Flat Roof Inspection and Survey: What to Look For, Common Failure Points and Condition Report Format
  Systematic survey methodology, felt/EPDM/GRP failure modes, IR thermography and ELD techniques, RICS three-grade condition rating, condition report format for customer-facing use
• Flat Roof Parapet Detailing: Coping Stones, Upstand Heights, Flashing and Thermal Bridging at Parapet
  Parapet upstand minimum 150mm above finished roof level (BS 6229:2018), coping stone DPC and drip detail, lead/GRP/EPDM flashing at parapet base, thermal bridging Ψ-values, five most common failure modes
• Flat Roof Repair vs Replacement: Patch Repair Limitations, When to Strip and Relay, and Cost-Benefit Arguments
  Patch repair limitations on aged felt, 20% blistering threshold, overlay vs strip (Part L 25% renovation trigger, 0.18 W/m²K), Party Wall Act notice, cost-benefit framework
• Flat Roof Skylights and Rooflights: Upstand Heights, Kerb Details, Planning Considerations and Thermal Performance
  150mm upstand at rooflight kerb (BS 6229:2018), timber vs prefabricated kerb, membrane termination, U-value ≤1.6 W/m²K for replacement (Part L 2021), permitted development 150mm projection limit, condensation diagnosis
• Green Roof Build-Up: Sedum Trays vs Extensive Substrate, Root Barrier, Drainage Layer and Structural Load
  Layer-by-layer green roof build-up (VCL → insulation → FLL-tested root barrier → drainage cell → filter fleece → substrate), extensive 60–150 kg/m² vs intensive 200+ kg/m², BS 8579:2019, BNG/Environment Act 2021
• GRP Fibreglass Flat Roofing: Installation Steps, Glass Mat Thickness, Topcoat Application and Common Defects
  GRP installation: 450g/m² CSM, 1–2% MEKP catalyst, key coat timing (hardened but not fully cured), topcoat application, common defects (delamination, crazing, dry patches)
• Inverted Roof System: XPS Insulation Above Waterproofing Layer, Ballast Requirements and Drainage Mat
  XPS insulation above waterproofing membrane, 100kg/m² minimum ballast, ISO 13165 moisture correction factor (fX = 0.04 W/m²K), 200–250mm XPS for 0.18 W/m²K target, no VCL needed
• NFRC and Flat Roofing Standards: CoP for Single-Ply, Built-Up Felt and Cold-Applied Systems — What Contractors Must Follow
  NFRC CoP 1 (built-up felt), CoP 2 (single-ply EPDM/PVC), CoP 3 (mastic asphalt), CoP 4 (cold-applied liquid/GRP): falls 1:80 minimum, 150mm upstands, warranty provider alignment
• Torch-On Felt Systems: SBS vs APP Modified Bitumen, Layer Build-Up, Safety and NFRC Guidance
  SBS vs APP modified bitumen: 2-layer minimum, 75mm side laps, hot works permit, dedicated fire watcher, 1-hour post-completion fire watch, NFRC CoP 1 compliance
• Warm Flat Roof Detail: Insulation Above Deck, Vapour Control Layer Position and Building Regs Part C Compliance
  Warm deck build-up: deck → VCL → PIR insulation → waterproofing membrane; VCL position (below insulation, not above); tapered insulation for falls; 0.18 W/m²K Part L target