403A Roofing Systems 2

Question 1

What causes ice dams on Canadian roofs and what is the primary prevention method?

Accepted Answer

Heat escaping through the roof melts snow, which refreezes at the eaves; adequate insulation and ventilation prevent them

Answer

High winds cause snow to melt; installing wind barriers prevents them

Answer

Rain freezing on cold shingles; heated gutters prevent them

Answer

Condensation from bathroom fans; proper duct routing prevents them

Question 2

What is roof sheathing and what material is most commonly used in Canadian residential construction?

Accepted Answer

Plywood or OSB panels nailed to the rafters or trusses to create the roof deck

Answer

Metal sheets fastened directly to the trusses

Answer

Concrete tiles set over purlins

Answer

Rigid foam insulation boards with integral nailing surfaces

Question 3

What is the purpose of step flashing where a roof meets a vertical wall?

Accepted Answer

To prevent water from penetrating the joint by directing it over each shingle course

Answer

To add structural support at the junction

Answer

To provide a decorative trim at the transition

Answer

To secure the wall sheathing to the roof framing

Question 4

What is the function of a drip edge on a roof?

Accepted Answer

To direct water away from the fascia and into the gutter

Answer

To add weight to the roof edge for wind resistance

Answer

To support the first course of shingles

Answer

To provide ventilation at the eave

Question 5

What is a valley in roofing and what are the two main methods of finishing it?

Accepted Answer

A valley is where two roof slopes meet forming a V-channel; finished with open metal valley or closed-cut (woven) shingles

Answer

A valley is the peak of a hip roof; finished with cap shingles or metal ridge

Answer

A valley is a low area in flat roofing; finished with extra membrane layers

Answer

A valley is the space between dormers; finished with siding or stucco

Question 6

When installing asphalt shingles, what is the recommended nail placement?

Accepted Answer

In the nailing strip (tar line) just above the cutout slots

Answer

At the top edge of the shingle

Answer

At the exposed portion of the shingle

Answer

Through both the shingle and the metal drip edge