Rooftop Waterproofing 101
Rooftop waterproofing is more than a single coating; it acts as a continuous barrier against rain, sun, and temperature swings. Without a proper system, even small breaches around seams and penetrations can grow into costly leaks. Choosing the right membrane matters: thermoplastic membrane, modified bitumen, or spray-applied polyurethane each has strengths depending on roof type. An effective rooftop plan starts with thorough surface preparation, repair of damaged concrete, and a clear slope toward drainage.
Insulation materials play a key role in long-term performance. Pairing waterproofing with suitable insulation improves energy efficiency and reduces condensation that can lead to corrosion on metal flashings. If you retrofit an old roof, use compatible insulation boards that won't trap moisture. Careful sequencing ensures insulation stays dry and doesn't compromise the waterproof layer.
When a kitchen hood or vent passes through a roof, the flashing must be integrated with the waterproof system. Use a proper curb flashing, curb sealant, and fire-rated sealant around the duct. Regular inspections, especially after heavy rains or wind events, help catch loose flashings before leaks appear.
Vent Penetrations on Roof
Vent penetrations are common weak points if not flashed correctly. Install pre-formed vent flashing or boot flashings that accommodate duct size. Exhaust fans for kitchens should have dampers and be routed to avoid backdrafts.
For commercial kitchens, consider explosion-proof exhaust vents and grease-rated flashings, which require robust sealing and metal flashing around the roof opening. Proper sealing around duct joints prevents grease and moisture from migrating into the roof structure.
Keep grease buildup under control by regular cleaning of ducts and hoods, and by inspecting the seal around penetrations. Schedule professional inspections to ensure flashing remains intact after major storms.
Maintenance and Upkeep Tips
Establish a seasonal inspection routine to catch early signs of wear, such as blistering, cracks, or peeling membranes. Inspect flashings around parapets, vents, and skylights for corrosion or loose fasteners. Clear gutters and strainers to ensure water drains away from the roof edge. Document findings and schedule timely repairs before minor issues become major leaks.
Keep insulation dry by protecting it from water intrusion and ensuring proper air barriers. If a leak is found, address it promptly with appropriate sealants and, if needed, re-flashing. Coordinate any major work, such as vent replacements or hood upgrades, to minimize roof exposure and ensure compatibility with the waterproof system.
During kitchen hood replacement, verify that new duct connections are sealed with fire-rated sealants and integrated into the roof flashing. Use only compatible sealants and membranes that meet local building codes and fire safety standards. Keep a maintenance log noting dates of inspections, repairs, and replacements to simplify future audits.