Red Seal Roofer flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fall protection threshold

On construction sites, fall protection is required at 3 m (10 ft) or more above a lower level; systems include guardrails, personal fall arrest with 100% tie-off, or safety nets.

Ladder slope rule

Extension ladders are set at a 4:1 slope (one unit out for every four units up), extend at least 1 m (3 ft) above the landing, and are secured at the top.

Kettle fill limit

Asphalt kettles are never filled above about 75% of capacity, must have a working thermometer and lid, and are kept at least 5 m (16 ft) from combustible material.

Roofing nail specification

Asphalt shingles require 11- or 12-gauge galvanized nails with a minimum 9.5 mm (3/8 in) head and 25 mm (1 in) penetration into the deck or through the sheathing.

Hot-air welder calibration

TPO and PVC seams are welded with a hot-air welder set to the manufacturer's temperature and speed; seam quality is confirmed by peel and probe tests, not by visual inspection.

Slope ratio to percent

Convert slope ratio to percent by multiplying by 100: a 4:12 slope equals 33.3%. Convert to degrees using the arctangent of the ratio, giving 18.4 degrees.

Low-slope definition

Low-slope roofing is a roof slope less than 2:12 (16.7%). Steep-slope roofing is 2:12 or greater, and this threshold determines which membrane or shingle system applies.

Specification hierarchy

The written specification governs over the drawings, and the manufacturer's published installation instructions govern over both when the specification is silent on a detail.

Sheathing gap requirement

Wood roof sheathing panels are spaced about 3 mm (1/8 in) apart at the edges to allow expansion and prevent buckling, and sheathing must be dry before roofing.

Eave ice-dam membrane

In cold climates, a self-adhering waterproofing membrane runs from the eave to at least 900 mm (36 in) inside the exterior wall line, with a drip edge installed over it.

Built-up roofing plies

Built-up roofing alternates layers of bitumen and reinforcing felt; a 4-ply system is common, and the finished membrane must be fully adhered with no voids.

Torch-applied membrane safety

Torch work on modified bitumen requires a hot-work permit, a fire extinguisher within 3 m, a fire watch, and a separation layer over combustible substrates such as wood or insulation.

Single-ply attachment methods

Single-ply membranes are fully adhered, mechanically attached, or ballasted; wind uplift resistance depends on the attachment method and the perimeter zone width.

Shingle exposure

Exposure is the exposed height of each shingle course; a standard 3-tab shingle uses a 143 mm (5 5/8 in) exposure, set by the manufacturer and determining courses per square.

Wood shingle spacing

Wood shingles and shakes are spaced 6-10 mm (1/4-3/8 in) apart to allow expansion and drainage, and are fastened with stainless steel or hot-dip galvanized nails.

Standing seam minimum slope

Standing seam metal roofing can be installed on slopes as low as 1:12 with a sealed seam, while exposed-fastener panels typically require a 3:12 slope or steeper.

Step flashing installation

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 reglet

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

Chimney cricket

A cricket is required on the high side of a chimney wider than 750 mm (30 in) to divert water around the chimney and prevent ponding against the flashing.

Ventilation ratio

Attic ventilation requires 1:300 net free vent area to ceiling area, reduced to 1:150 when the vapour retarder is inadequate; intake and exhaust vents are balanced equally.

Vapour barrier perm rating

A material with a perm rating of 0.1 or less is a vapour barrier; a perm rating between 0.1 and 1.0 is a vapour retarder, and placement is on the warm side.

Tapered insulation purpose

Tapered insulation boards create the minimum 1:50 (2%) slope to drains on low-slope roofs, preventing ponding water that can void membrane warranties.

Reroof over existing

Reroofing over existing shingles is allowed only with one existing layer, a sound deck, and total weight within structural capacity; two layers is the usual maximum.

Leak tracing

Water travels along the deck, so leaks are traced uphill from the stain; flashings, valleys, and penetrations are checked before the membrane is replaced.

BUR blister repair

A blister in built-up roofing is cut out to sound membrane, the area dried, and patched with a new ply of felt and bitumen extending 100 mm (4 in) beyond the repair.

Silica dust control

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.

Membrane incompatibility

EPDM is incompatible with asphalt, polystyrene insulation, and most oils; TPO and PVC are incompatible with asphalt and with each other, requiring separation layers.

Valley metal width

Open valleys use a 600 mm (24 in) wide metal pan centered on the valley line, installed over the underlayment and under the shingles, trimmed 75-100 mm (3-4 in) from center.

Rafter length calculation

Rafter length equals the plan run divided by the cosine of the slope angle, or the plan run multiplied by the slope factor, which is 1.054 for a 4:12 slope.

Steel deck fastener penetration

Insulation fasteners on low-slope roofs must penetrate the steel deck by at least 25 mm (1 in), or 19 mm (3/4 in) into wood, to develop the required pull-out capacity.

Tile underlayment rule

Clay and concrete tile require a minimum 3:12 slope for standard installation and a double underlayment on slopes below 4:12, with two fasteners per tile at the perimeter.

Secondary roof drain

A secondary or emergency drain or scupper is set at least 50 mm (2 in) above the primary drain so the roof can drain if the primary drain becomes blocked.