Red Seal Roofer cheat sheet

Fall protection is required at 3 m (10 ft) or more on construction sites; guardrails, personal fall arrest with 100% tie-off, or a safety net are acceptable systems, and the anchor point must support 22 kN (5,000 lb) per worker.

Ladder setup rule: 4:1 slope for extension ladders, 1 m (3 ft) minimum extension above the landing, and secure the top; roof ladders or roof jacks are required for steep-slope work above the eave line.

Asphalt kettle and tanker work: keep a 5 m (16 ft) clearance from combustible material, maintain a functional thermometer and lid, never fill above 75% capacity, and never heat bitumen above its flash point.

Hot bitumen burns: flash point of typical roofing asphalt is above 230 C (450 F) but molten material at 200 C causes deep burns; PPE is a face shield, heat-resistant gloves, long sleeves, and boots, not just safety glasses.

Controlled deck work: a written hazard assessment and fall rescue plan are required before any worker goes on a roof with unprotected edges, skylights, or openings; skylights must be guarded or covered to support twice the intended load.

Respiratory protection: adhesives, solvents, and polyurethane foam require cartridge respirators or supplied air per SDS; half-mask respirators require fit testing and medical clearance under CSA Z94.4.

Ladders, scaffolds, and roof jacks must be inspected before each shift; damaged side rails, missing rungs, or bent scaffold frames are removed from service and tagged.

Silica and dust: cutting tile, concrete, or fibre-cement with a power saw requires wet cutting or a dust-collection shroud plus a respirator; dry sweeping is prohibited on most sites.

Waste handling: asphalt shingles, membrane scraps, and mastic containers are separated for recycling or landfill per local bylaws; solvent and adhesive containers are closed and stored in a ventilated area away from ignition.

Nail selection for asphalt shingles: 11- or 12-gauge galvanized, annular-thread or smooth-shank roofing nails with a minimum 9.5 mm (3/8 in) head and 25 mm (1 in) penetration into roof sheathing or through the deck.

Fastener corrosion classes: hot-dip galvanized (ASTM A153) for standard exposure, stainless steel or silicon bronze for coastal and treated-wood contact, and electro-galvanized is not acceptable for roofing.

Roofing nail guns must be adjusted so the nail head is flush with the shingle surface, not overdriven (cuts the mat) or underdriven (abrades the shingle above).

Membrane seam equipment: hot-air welders must be calibrated to the membrane manufacturer's temperature and speed; seam strength is verified by peel and probe tests, not visual inspection alone.

Bitumen kettle capacity and burner output are matched to the job; a 100 kg kettle heats about 100 kg of asphalt in 45-60 minutes; never exceed the manufacturer's maximum heating temperature.

Hand tool set for steep-slope work: roofing hatchet with gauge, utility knife with hook blades, tin snips, chalk line, pry bar, and a shingle stripper; power tools include a shingle cutter and a coil nailer.

Ladder and pump jack systems for steep-slope: pump jacks with 40 mm (1.5 in) scaffold-grade planks, roof brackets with 50 x 150 mm (2 x 6 in) planks, and toe boards at the eave.

Fastener pattern for metal roofing: screws are placed in the flat of the panel at the purlin, with a neoprene washer compressed but not crushed; over-torquing splits the washer and leaks.

Material compatibility: EPDM is incompatible with asphalt, polystyrene insulation, and most oils; TPO and PVC are incompatible with asphalt and with each other's plasticizers, so separation layers are required.

Roof slope is expressed as rise over run; convert to percent by multiplying the ratio by 100 (4:12 = 33.3%), and to degrees with arctangent (4:12 = 18.4 degrees).

Low-slope is defined as a slope less than 2:12 (16.7%); steep-slope is 2:12 or greater; the threshold drives the choice of membrane versus shingle or tile.

Reading the roof plan: identify ridge, hip, valley, eave, rake, and slope arrows; slope arrows point downhill and are perpendicular to the contour lines.

Line lengths on a roof plan are true only in plan view; rafter length equals the plan run divided by the cosine of the slope angle, or use the slope factor (4:12 factor = 1.054).

Specification hierarchy: the written specification governs over the drawings, and the manufacturer's published installation instructions govern over both when the specification is silent.

Layout of shingle courses: establish a starter course at the eave, snap horizontal chalk lines every 5 courses, and offset vertical joints by at least 150 mm (6 in) between courses.

Valley layout: open valleys use a 600 mm (24 in) wide metal pan centered on the valley line; woven valleys require the steeper roof plane to be laid first and the cross-woven shingles trimmed to the valley centerline.

Takeoff formula: number of shingle bundles = roof area in squares (100 sq ft each) times 3 bundles per square, plus 10% waste for hips and valleys; membrane rolls are ordered by roll width times length.

Datum and elevation: roof drains and scuppers are set to the structural deck elevation plus insulation thickness plus membrane; verify with a laser level before installing the drain ring.

Wood decking for steep-slope: minimum 19 mm (3/4 in) tongue-and-groove plywood or OSB with 3 mm (1/8 in) gaps between panels, fastened with 8d ring-shank nails at 150 mm (6 in) on center at edges and 300 mm (12 in) in the field.

Sheathing must be dry before roofing; moisture content above 19% in wood sheathing traps vapour and causes blistering or rot, so allow drying or replace wet panels.

Low-slope structural deck options: steel deck with 1.5 in deep profile, concrete, or wood; each has a specific fastener and adhesive requirement, and the deck must be clean, dry, and free of oil.

Deck repair: replace delaminated plywood, sister rotted rafters, and re-nail loose sheathing; a 3 mm (1/8 in) gap is required at panel edges to allow expansion and prevent buckling.

Roof slope correction: tapered insulation or a lightweight concrete fill creates the minimum 1:50 (2%) slope to drains; ponding water indicates insufficient slope or deflection.

Substrate priming: concrete and steel decks require a primer compatible with the membrane adhesive; asphalt-based primer is not used under EPDM or TPO.

Vapour barrier placement: on the warm side of the insulation; in cold climates place the vapour retarder below the insulation and provide ventilation above it in steep-slope assemblies.

Eave protection and ice dam: in cold climates install a self-adhering membrane from the eave to at least 900 mm (36 in) inside the exterior wall line, plus a drip edge over the membrane.

Fastener pull-out testing on steel deck: verify screw pull-out capacity meets the wind uplift design pressure before installing the membrane; a test pull-out of 3 fasteners per 100 m2 is typical.

Built-up roofing (BUR): alternating layers of bitumen and reinforcing felt; a 4-ply system is common, and the finished membrane must be fully adhered with no voids or fishmouths.

BUR bitumen application temperatures: asphalt is applied at 200-230 C (400-450 F) for mopping; the interply bitumen temperature is measured with a thermometer, not estimated.

Modified bitumen (SBS and APP): SBS is torch-applied or hot-mopped and stays flexible at low temperature; APP is torch-applied and has higher heat resistance; torch work requires a hot-work permit and a fire watch.

Torch-applied membrane safety: keep a fire extinguisher within 3 m, protect combustible substrates with a separation layer, and never torch directly onto insulation or wood without a gypsum cover board.

Single-ply attachment methods: fully adhered, mechanically attached, and ballasted; wind uplift resistance depends on the attachment method and the perimeter zone width, which is typically 40% of the building height.

TPO and PVC seams: hot-air welded with a minimum 40 mm (1.5 in) weld; probe the seam with a dull tool and pull-test a sample; EPDM seams are spliced with contact adhesive or a splice tape and rolled with a seam roller.

Membrane terminations: at walls, the membrane is carried up at least 200 mm (8 in) above the roof surface and terminated in a reglet or with a termination bar and sealant.

Roof drains and scuppers: install a clamping ring and strainer, set the drain flange into the membrane with a compatible sealant, and ensure the drain is the low point of the roof.

Protection board and walkway pads are installed over the membrane in high-traffic areas and under ballast to prevent puncture; ballast weight is typically 50-100 kg/m2 depending on wind design.

Asphalt shingle exposure: standard shingles are laid with a 143 mm (5 5/8 in) exposure for a 3-tab shingle; the exposure is set by the manufacturer and determines the number of courses per square.

Starter course: a dedicated starter strip or inverted shingle is installed along the eave and rake, with nails placed above the exposure line so the next course covers them.

Wood shingles and shakes: shingles are sawn and shakes are split; use stainless steel or hot-dip galvanized nails, and maintain a 6-10 mm (1/4-3/8 in) gap between shingles for expansion and drainage.

Wood roof ventilation and fire: wood roofs require a ventilated air space beneath and, in wildland-urban interface areas, fire-retardant-treated shakes or a fire-resistant underlayment.

Tile roofing: clay and concrete tiles require a minimum 3:12 slope for standard installation, a double underlayment for slopes below 4:12, and fasteners that resist wind uplift at the perimeter.

Tile fastening: each tile is fastened with two corrosion-resistant screws or nails into the batten; battens are spaced according to tile exposure and are counter-battened for drainage.

Metal roofing: standing seam panels are attached with concealed clips that allow thermal movement; exposed-fastener panels use screws with neoprene washers at the ribs or flats per the manufacturer.

Metal roof minimum slope: standing seam can go down to 1:12 with a sealed seam; exposed-fastener panels typically require 3:12 or steeper.

Underlayment selection: a high-temperature self-adhered underlayment is required under metal and tile; synthetic underlayment is used under asphalt shingles, and felt is acceptable where the code permits.

Step flashing at sidewalls: each shingle course receives a 100 x 100 mm (4 x 4 in) L-shaped flashing piece, overlapped 50 mm (2 in) by the next piece and covered by the shingle above.

Counterflashing: the upper flashing is set into a reglet cut 25 mm (1 in) deep in masonry and sealed with a compatible sealant; the counterflashing overlaps the base flashing by at least 100 mm (4 in).

Valley flashing: open valleys use a 600 mm (24 in) wide metal pan; the valley metal is installed over the underlayment and under the shingles, with the shingles trimmed 75-100 mm (3-4 in) from the valley centerline.

Roof-to-wall and chimney flashing: use a cricket on the high side of a chimney wider than 750 mm (30 in) to divert water, and a base flashing with a 150 mm (6 in) vertical leg.

Drip edge: installed at the eave over the underlayment and under the shingle starter course, with a 6 mm (1/4 in) gap to the fascia for water shedding.

Roof drain and scupper details: a secondary (emergency) drain or scupper is required, set at least 50 mm (2 in) above the primary drain, to handle blocked primary drainage.

Waterproofing at penetrations: pipe boots and pitch pans are sealed with a compatible sealant and a clamping collar; pitch pans are filled with a flexible sealant, not asphalt, on single-ply roofs.

Ice dam and eave protection: a self-adhering membrane at the eave extends at least 900 mm (36 in) inside the exterior wall line in cold climates; gutters must be sized to the roof area and slope.

Ventilation rule: 1:300 ratio of net free vent area to ceiling area, reduced to 1:150 when the vapour retarder is not adequate; balance intake (soffit) and exhaust (ridge) vents equally.

Insulation R-value: roof insulation is specified by RSI (metric) or R-value (imperial); 1 inch of polyisocyanurate is about R-6, and tapered insulation is used to create slope to drains.

Vapour retarder: placed on the warm side of the insulation; a perm rating of 0.1 or less is a vapour barrier, and a perm rating between 0.1 and 1.0 is a vapour retarder.

Attic ventilation: provide a 25 mm (1 in) air space between the insulation and the roof sheathing at the eave to allow air flow; baffles are installed at each rafter bay.

Condensation control: in cold climates, the ceiling air barrier must be continuous and sealed at penetrations; a leaky ceiling plane causes condensation on the cold roof sheathing.

Insulation fastening: insulation boards on low-slope roofs are fastened with screws and plates or adhered; fastener length must penetrate the deck by at least 25 mm (1 in) for steel and 19 mm (3/4 in) for wood.

R-value and dew point: adding insulation above the deck moves the dew point; a dew-point calculation confirms whether a vapour retarder is needed in the assembly.

Roof ventilation for steep-slope: ridge vents, soffit vents, and gable vents must be balanced; a ridge vent requires a continuous slot cut at the ridge and an air-permeable ridge cap.

Reroofing over existing shingles: permitted only if the existing roof is one layer, the deck is sound, and the total weight does not exceed the structural capacity; two layers of shingles are the maximum in most codes.

Tear-off versus overlay: tear-off is required when the existing roof has two or more layers, when the deck is deteriorated, or when the new membrane requires a clean substrate.

Leak diagnosis: water travels along the deck; trace the leak uphill from the stain, and check flashings, valleys, and penetrations before replacing the membrane.

Blister and ridge repair in BUR: cut out the blister to sound membrane, dry the area, and patch with a new ply of felt and bitumen, extending 100 mm (4 in) beyond the repair.

Single-ply repair: clean the membrane with the manufacturer's cleaner, apply a patch of the same membrane at least 50 mm (2 in) larger than the defect, and weld or adhere per the system.

Shingle repair: replace cracked or missing shingles by breaking the seal of the course above, sliding out the damaged shingle, and nailing the new shingle with the head covered by the course above.

Maintenance schedule: inspect the roof twice a year and after major storms; clear drains and scuppers, remove debris, and check sealant joints and fasteners.

Moisture survey: infrared thermography or a capacitance meter locates wet insulation; wet areas are cut out and replaced, not covered over.

Roof warranty: manufacturer warranties require installation by an approved applicator and may be voided by ponding water, incompatible materials, or lack of maintenance records.