Deck 33: Roofing-I Low-Slope Roofs

Question 1

A built- up roof membrane is generally finished with

A)a single- ply roof membrane.
B)a flood coat of bitumen.
C)aggregate surfacing.
D)all of the above.
E)B and C.

Answer 1

E

Question 2

A dragon wagon is used in laying

A)a modified bitumen roof membrane.
B)a built- up roof membrane.
C)a single- ply roof membrane.
D)all of the above.
E)none of the above.

Answer 2

A

Question 3

Which of the following built- up roof membranes is more commonly used?

A)Asphalt built- up roof membrane
B)Tar built- up roof membrane

Answer 3

A

Question 4

Bitumen- treated fiberglass felt

A)is more porous than bitumen- treated organic felt.
B)is less porous than bitumen- treated organic felt.
C)has the same porosity as bitumen- treated organic felt.
D)none of the above.

Question 5

Of the two single- ply roof membranes, EPDM and PVC, PVC is generally

A)less flexible and less fire resistant.
B)more flexible and more fire resistant.
C)less flexible but more fire resistant.
D)more flexible but less fire resistant.

Question 6

Which of the following represents an asphalt- treated fiberglass felt?

A)Type II
B)Type III
C)Type IV
D)No. 15
E)No. 30

Question 7

Which of the following modified bitumen membranes is generally torch applied?

A)APP- modified bitumen
B)SBS- modified bitumen

Question 8

Asphalt is a waste product obtained from

A)the manufacturing of steel.
B)the manufacturing of coal tar.
C)the manufacturing of rubber.
D)petroleum refining.
E)none of the above.

Question 9

The lap seams in an EPDM roof membrane are typically sealed by

A)heat welding.
B)liquid adhesives.
C)single- sided tape.
D)double- sided tape.
E)any one of the above.

Question 10

EPDM is a thermosetting plastic.

Question 11

A low- slope roof is defined as a roof whose slope is less than

A)1:12.
B)1)5:12.
C)2:12.
D)3:12.
E)2)5:12.

Question 12

Which of the following roofing asphalts is commonly used for mopping an SBS- modified bitumen membrane?

A)Type I
B)Type II
C)Type III
D)Type IV
E)SBS- modified asphalt

Question 13

The lap seams in a PVC roof membrane are typically sealed by

A)heat welding.
B)liquid adhesives.
C)single- sided tape.
D)double- sided tape.
E)any one of the above.

Question 14

The weight of aggregate surfacing on a built- up roof is generally

A)15 lb per roof square.
B)40 lb per roof square.
C)25 lb per roof square.
D)400 lb per roof square.
E)5 lb per roof square.

Question 15

Low- slope roofs are more commonly used than steep roofs.

Question 16

Which of the following modified bitumen membranes is more elastomeric?

A)SBS- modified bitumen
B)APP- modified bitumen

Question 17

A roof square implies

A)100 ft2 of roof area.
B)10 m2 of roof area.
C)1 m2 of roof area.
D)10 ft2 of roof area.
E)1 ft2 of roof area.

Question 18

Because of the general trend toward sustainable and organic construction, organic felts are increasingly replacing fiberglass felts in built- up roofs.

Question 19

The lap seams in a TPO roof membrane are typically sealed by

A)heat welding.
B)liquid adhesives.
C)single- sided tape.
D)double- sided tape.
E)any one of the above.

Question 20

Which of the following roofing asphalts is commonly used for interply mopping?

A)Type I
B)Type II
C)Type III
D)Type IV
E)None of the above

Question 21

A mechanically fastened single- ply roof membrane is generally used with

A)steel roof decks.
B)precast- concrete decks.
C)reinforced- concrete decks.
D)none of the above.

Question 22

Counterflashing is generally

A)made of PVC and is a removable item.
B)made of PVC and is permanently anchored to the deck or parapet wall.
C)made of sheet metal and is a removable item.
D)made of sheet metal and is permanently anchored to the deck or parapet wall.
E)none of the above.

Question 23

UL Class B represents

A)the fire rating of a roof assembly.
B)the wind- uplift resistance of a roof assembly.
C)the hail- impact resistance of a roof assembly.
D)none of the above.

Question 24

The exposure (EX)of felts in a four- ply built- up roof is

A)2 in.
B)4 in.
C)8 in.
D)6 in.
E)none of the above.

Question 25

With a steel deck topped with lightweight insulating concrete, the commonly used board insulation is

A)iso board.
B)not used with insulating concrete.
C)expanded polystyrene (EPS)board.
D)polyurethane board.

Question 26

FM 1- 120 represents

A)the fire rating of a roof assembly.
B)the wind- uplift resistance of a roof assembly.
C)the hail- impact resistance of a roof assembly.
D)none of the above.

Question 27

In a protected membrane roof, the insulation is

A)between the deck and the membrane.
B)above the membrane and fully adhered to it.
C)above the membrane but loose laid over it.
D)below the deck.
E)not used.

Question 28

A loose- laid ballasted roof is generally used with

A)a single- ply membrane.
B)a modified bitumen membrane.
C)a built- up roof membrane.
D)all of the above.

Question 29

Approximately how often is a typical building reroofed?

Question 30

The flashing around a roof drain is

A)curb flashing.
B)flange flashing.
C)base flashing
D)none of the above.

Question 31

For a building located in a high- wind region, which of the following roof systems is most suitable?

A)Fully adhered single- ply system
B)Protected membrane system
C)Loose- laid ballasted single- ply system
D)Mechanically fastened single- ply system
E)Gravel- covered built- up roof

Question 32

On which of the two types of roofs (low- slope roofs and steep roofs)are the roof coverings more durable and why?

Question 33

FM MH represents

A)the fire rating of a roof assembly.
B)the wind- uplift resistance of roof assembly.
C)the hail- impact resistance of roof assembly.
D)none of the above.

Question 34

How does the building industry distinguish between a low- slope roof and a steep roof?

Question 35

A slotted steel roof deck is mandated for use with

A)lightweight insulating concrete.
B)foamed concrete.
C)all rigid board insulations.
D)none of the above.

Question 36

Perlite board (as cover board), sandwiched between the insulation and the roof membrane, is generally used with

A)a fully adhered single- ply membrane.
B)a loose- laid, ballasted single- ply membrane.
C)a mechanically fastened single- ply membrane.
D)an asphalt- mopped membrane.

Question 37

A cant strip is not required in a base flashing detail with a single- ply roof membrane.

Question 38

The flashing around a pipe penetrating through the roof is

A)flange flashing.
B)base flashing
C)curb flashing.
D)none of the above.

Question 39

The cover board generally used between a single- ply roof membrane and rigid board insulation is

A)extruded polystyrene board.
B)glass- fiber- reinforced gypsum board.
C)specially treated perlite board.
D)iso board.
E)none of the above.

Question 40

The head lap in a four- ply built- up roof is

A)5 in.
B)4 in.
C)6 in.
D)2 in.
E)none of the above.

Question 41

List the five components of a low- slope, membrane roof starting from the top, going down.

Question 42

A built- up roof (BUR)membrane consists of several plies of felt, where each successive felt is laid over a mopping of asphalt. Does the performance of a BUR membrane depend on the number of plies? What is the maximum and minimum number of plies used in a BUR membrane?

Question 43

Which cover board is commonly used with single- ply, low- slope roofs and what is its thickness?

Question 44

Built- up roof (BUR)felts are available in Type IV and Type VI felts. Why is Type VI felt generally preferred to provide a better BUR membrane?

Question 45

In how many types is roofing asphalt available? Which asphalt is used for interply mopping, i.e., mopping of felts in a built- up roof (BUR)membrane?

Question 46

Which of the two types of roofs (low- slope roofs and steep roofs), has a greater market share?

Question 47

Can we have a roof on a building with no slope, i.e., a dead- flat roof? Explain.

Question 48

List the three types of roof membranes used on low- slope roofs.

Question 49

Which cover board is commonly used with hot- mopped built- up and modified- bitumen roofs and what is its thickness?

Question 50

What is the typical width and length of built- up roof felt rolls?

Question 51

In a low- slope roof, the cover board has several functions. List the four most important functions.

Question 52

A built- up roof (BUR)membrane consists of several plies of felt, where each successive felt is laid over a mopping of asphalt. What does the felt consist of and what is its purpose? What purpose does asphalt serve?

Question 53

What is a roof square and how is it related to the dimensions of built- up roof (BUR)felt roll?

Question 54

A built- up roof (BUR)membrane consists of several plies of felt, where each successive felt is laid over a mopping of asphalt. The last ply in a BUR is not the same as the underlying plies. What is the difference and why?

Question 55

What is the primary reason for the use of low- slope roofs on commercial buildings in place of steep roofs?

Question 56

A built- up roof (BUR)membrane consists of several plies of felt, where each successive felt is laid over a mopping of asphalt. The felt consists of glass fibers, woven into a mat, which is porous. Although the BUR membrane is meant to waterproof the roof, the porosity of felts is considered an advantage. Why?

Question 57

The roof membranes on a low- slope roof consist of one the following: built- up roof membrane,
modified- bitumen roof membrane, or single- ply roof membrane. Which of these membranes are hot- mopped or heat- applied?

Question 58

Explain why low- slope roof components (membrane, cover board, insulation, adhesives, and fasteners)must be obtained from the same manufacturer.

Question 59

Built- up roof felts are available in Type IV and Type VI. Explain the difference between them.

Question 60

A built- up roof (BUR)consists of multiple plies where a ply is defined as one felt field mopped with asphalt. The thickness of one BUR ply is approximately 30 mil. A modified bitumen roof (MBR), on the other hand, consists of modified bitumen sheets. What is the composition of a modified bitumen sheet and its typical thickness?

Question 61

An SBS- modified bitumen membrane may consist of two plies of SBS- modified bitumen sheets, applied with hot mopping of asphalt. Which type of asphalt is used for mopping the sheets?

Question 62

Describe the attachment method of various components (insulation, cover board and membrane)of a built- up roof (BUR)on a steel deck.

Question 63

Lap splices in thermoplastic single- ply roof membranes (PVC and TPO)are heat sealed. Is the equipment used for heat sealing an open flame, like the one used for APP modified bitumen sheets? Explain.

Question 64

A single- ply roof (SPR)membrane is made of polymers (plastics), available in thermosetting type or thermoplastic type. Give examples of commonly used SPR membranes in both types of plastics.

Question 65

The asphalt used in modified bitumen sheets is modified asphalt, which is of two types: SBS modified and APP modified asphalt. What are the differences between the two?

Question 66

List two important advantages of single- ply roof (SPR)membrane over built- up roof (BUR)and modified- bitumen roof (MBR)membranes.

Question 67

A single- ply roof membrane is made of polymers (plastics), which are available in two types. Give the names of the polymers and the differences between them.

Question 68

What is a modified- bitumen roof and built- up roof hybrid? Explain.

Question 69

What are the limitations of torch application of modified- bitumen sheets as compared with hot- mopping?

Question 70

What are the advantages of torch application of modified- bitumen sheets as compared with hot- mopping?

Question 71

Describe the attachment method of various components (insulation, cover board and membrane)of a fully mopped single- ply roof (SPR)membrane on a steel deck.

Question 72

A built- up roof membrane is fully adhered to the substrate (typically the cover board)using hot asphalt as adhesive. Modified- bitumen membrane is also fully adhered-either through hot mopping or torch application. How is a single- ply roof (SPR)membrane adhered?

Question 73

A modified- bitumen sheet may also be torch applied in place of mopping of hot asphalt. Which of the two bitumen sheets-SBS- modified bitumen sheet or APP- modified bitumen sheet-is generally torch- applied?

Question 74

An SBS- modified bitumen membrane may consist of two plies of SBS- modified bitumen sheets, applied with hot mopping of asphalt. What is the difference between the two sheets?

Question 75

List two important limitations of single- ply roof (SPR)membrane over built- up roof (BUR)and modified- bitumen roof (MBR)membranes.

Question 76

Name the two commonly used methods of providing slope in low- slope roofs. Which method is preferable and why?

Question 77

Describe the attachment method of various components (insulation, cover board and membrane)of a mechanically fastened EPDM roof membrane on a steel deck.

Question 78

Describe the attachment method of various components (insulation, cover board and membrane)of a fully mopped single- ply roof (SPR)membrane on a reinforced concrete deck.

Question 79

The insulation in a low- slope roof may consist of board insulation or non- board insulation. Which board insulation is most commonly used and why? Give its R- value per inch thickness.

Question 80

Lap splices in some single- ply roof (SPR)membranes are heat fused and in the other, they are adhered with double- sided tape. Name the membranes in which heat- fusing of splices is done and the membrane in which double- sided tape is used.