Roofing Installation Inspection

Per NBC Part 5 and CSA A123 series, the roof deck must provide a sound, dry, and clean substrate for roofing membrane application. Steel deck must conform to CSA S136 requirements, and concrete decks must be adequately cured and dried. The substrate must be free of sharp projections, debris, and standing water. Slope to drain must meet NBC minimum requirements of 1:50 (2%) per NBC 5.6.1.1.

1. Verify roof deck is structurally sound, properly fastened, and free of excessive deflection per design specifications

2. Confirm concrete decks have been adequately cured and moisture content is within acceptable limits using a moisture metre

3. Check that deck surface is clean, dry, and free of sharp projections, oil, and debris

4. Verify slope to drain meets the minimum 1:50 (2%) requirement per NBC 5.6.1.1

5. Confirm all deck penetrations and curbs are in place and properly flashed before membrane installation

- Standing water on deck indicating inadequate slope or blocked drains

- Steel deck panels not properly lapped or fastened causing movement under membrane

- Concrete deck moisture too high leading to blistering of adhered membranes

- Debris and sharp objects left on deck puncturing membrane during installation

Per NBC 5.6.1.2 and NBC 9.26.3, a vapour barrier must be installed on the warm side of the insulation to prevent moisture migration into the roofing assembly. The vapour barrier must have a permeance not exceeding 60 ng/(Pa-s-m2) per NBC 9.25.4.2. All laps and penetrations must be sealed to maintain vapour barrier continuity.

1. Verify vapour barrier material meets the maximum permeance rating specified in the design per NBC 9.25.4.2

2. Confirm vapour barrier is installed on the warm side of the roof insulation assembly

3. Check that all laps are sealed with compatible adhesive or tape with minimum 75 mm overlap

4. Verify all penetrations (pipes, ducts, structural supports) are properly sealed around the vapour barrier

5. Confirm vapour barrier is continuous and free of tears, punctures, or unsealed joints

- Vapour barrier installed on the wrong side of insulation allowing condensation within the assembly

- Laps not properly sealed creating gaps that allow moisture migration

- Penetrations left unsealed compromising vapour barrier continuity

- Vapour barrier damaged during subsequent trade work and not repaired

Per NBC 9.25.2 and the National Energy Code of Canada for Buildings (NECB), roof insulation must achieve the minimum effective RSI value for the climate zone. Insulation boards must be installed in staggered layers with offset joints per NRCA guidelines. Polyisocyanurate, expanded polystyrene (EPS), or extruded polystyrene (XPS) boards must conform to CAN/ULC-S701 or CAN/ULC-S704 as applicable.

1. Verify insulation type and thickness match design specifications and achieve the required effective RSI value per NBC or NECB

2. Confirm insulation boards conform to CAN/ULC-S701 or CAN/ULC-S704 and are labelled accordingly

3. Check that boards are installed in staggered layers with joints offset minimum 150 mm between layers

4. Verify boards are tightly butted with no gaps exceeding 6 mm and are mechanically fastened or adhered per manufacturer requirements

5. Confirm insulation is kept dry during storage and installation

- Insulation thickness insufficient to meet effective RSI requirements for the climate zone

- Joints not staggered between layers creating thermal bridges

- Insulation boards stored improperly on site and saturated with moisture before installation

- Gaps between boards left unfilled creating thermal weak points

Per CSA A123.21 and NBC Part 5, roofing membranes must be installed in accordance with the manufacturer's written instructions and applicable CSA standards. SBS or APP modified bitumen membranes must meet CAN/CGSB-37.54M. Single-ply membranes (TPO, EPDM, PVC) must meet CAN/CGSB-37.56M or manufacturer specifications. Membrane attachment must resist design wind uplift pressures per NBC 4.1.7.

1. Verify membrane type matches specifications and product data sheets are on site

2. Confirm membrane is applied per manufacturer's written instructions including temperature limitations

3. Check that all seams and laps meet minimum overlap requirements (typically 75-100 mm) and are fully bonded or welded

4. Verify membrane attachment method (adhered, mechanically fastened, or ballasted) resists design wind uplift per NBC 4.1.7

5. Confirm no wrinkles, fishmouths, or bridging exist in the installed membrane

- Membrane applied in cold temperatures below manufacturer's minimum causing poor adhesion

- Seam laps not fully bonded or heat-welded leaving open channels for water entry

- Insufficient fastener density in high wind uplift zones at corners and perimeters

- Fishmouths and wrinkles at laps creating paths for moisture infiltration

Per NBC 9.26.4 and NRCA guidelines, all roof penetrations, edges, walls, and transitions must be properly flashed. Base flashings must extend a minimum of 200 mm above the roof surface per NBC 9.26.4.4. Metal counter-flashings must be secured into reglets or receivers. Flashing materials must be compatible with the roofing membrane and must be turned into or over the membrane system.

1. Verify base flashings extend a minimum of 200 mm above the finished roof surface per NBC 9.26.4.4

2. Check that counter-flashings are secured into reglets or receivers and overlap base flashings by at least 75 mm

3. Confirm all pipe penetrations have properly sized and sealed pitch pockets or prefabricated boots

4. Verify edge flashings are properly lapped, sealed, and mechanically fastened at maximum 300 mm centres

5. Check that all flashing materials are compatible with the roofing membrane system

- Base flashing height less than 200 mm allowing water infiltration at wall-to-roof junctions

- Counter-flashings not properly secured into reglets, pulling away from walls

- Pipe boots and pitch pockets cracked or poorly sealed around penetrations

- Incompatible flashing materials causing deterioration at contact points

Per NBC 5.6.1.1 and NBC 9.26.8, roofs must be designed to drain water to approved drains, scuppers, or gutters. Internal roof drains must have strainers and be connected to the storm drainage system per the National Plumbing Code of Canada. Overflow drains or scuppers must be provided as secondary drainage per NBC 5.6.1.1 to prevent ponding loads from exceeding structural capacity.

1. Verify primary drains are installed at low points and connected to the storm drainage system per the National Plumbing Code

2. Confirm overflow drains or scuppers are installed and set at a maximum of 50 mm above the primary drain level

3. Check that drain strainers are in place and the membrane is properly clamped into drain bowls

4. Verify gutters and downspouts are properly sized for the roof area and securely fastened

5. Confirm no ponding water remains on the roof 48 hours after rainfall

- Drains not located at actual low points due to deck deflection or construction tolerances

- Overflow drainage not provided creating risk of structural overload from ponding

- Membrane not properly clamped into drain bowls causing leaks at drain connections

- Gutters undersized for the roof area leading to overflow during heavy precipitation

Per NBC Part 5 and NRCA guidelines, a final inspection must be conducted to verify the complete roofing assembly is watertight and installed per specifications. A flood test or electronic leak detection survey is recommended for critical roofing installations. The roofing contractor must provide a manufacturer's warranty inspection report, as-built drawings, and maintenance documentation.

1. Conduct a visual walk-over of the entire roof surface checking for defects, debris, and incomplete work

2. Perform a flood test (where feasible) or infrared scan to detect trapped moisture or leaks

3. Verify all sheet metal, flashings, sealants, and terminations are complete and properly installed

4. Confirm roofing contractor has provided manufacturer's warranty documentation and as-built drawings

5. Check that roof access hatches, walkway pads, and fall protection anchors are properly installed per CSA Z797

- Defects missed during final inspection discovered only after first significant rainfall

- Manufacturer's warranty voided due to installation deviations not documented during construction

- Roof traffic damage occurring between substantial completion and occupancy

- Missing or inadequate roof access and fall protection provisions for future maintenance