1. ROOF DECKS
Information taken from UURWAW’s training manuals, NRCA’s Roofing & Waterproofing Manual 5th Edition, and Johns Manville web site.
Materials: videos: Ballooned EPDM, Welcome to canaam1, N.J. Roofer Falls 40’

2. ROOF DECKS Objectives: Functions of Roof Decks Types of Decks
Slopes and Drainage
The deck is the foundation of any effective roof system
Decks change according to the climate, load imposed, and intended roof system

3. Deck Function
There are many considerations of the deck type and design that go well beyond an even substrate.
Some decks are designed to furnish inside appearance as well as sound control.

4. FUNCTION
As part of the roof assembly the deck should be designed to provide:
Structural support
Go to the flip chart and ask, “What’s the purpose of the roof deck”? Expected answer, “A substrate to lay a roof over.”
A roof deck should provide structural support, dimensional stability, fire resistance and a substrate for the roof system.
It also should accommodate building movement, have adequate strength and rigidity to support all anticipated live and dead loads.
The deck must have adequate strength and rigidity to carry the weight of the roofers and their equipment during construction, without deflecting to the point where roofing components rupture, delaminate, or are weakened. Slope for drainage should be provided by sloping the roof deck, using tapered fill or insulation, or combination of both.
Prior to application of the roof system, a deck should be inspected to determine that it is smooth; straight; and free of irregularities, such as significant humps or depressions. If the deck Is composed of panels or planks, the roofing contractor should check to see that adjacent deck sections are aligned vertically on the same plane. The deck should provide a substrate that will accommodate the application of specified roofing materials.

5. Structural Support 5

6. Structural Support
A deck transfers the weight of live and dead loads to supporting framing members.
Joist
Purlins
Subpurlins
Live loads include environmental loads, such as snow, rain, ice, wind and other non-stationary loads, such as workers and mobile installation equipment.
Dead loads include stationary loads, such as topside and under­ side mechanical equipment, weight of the deck, any sheathing overlayment, roof membrane, insulation and ballast.
Purlin: A horizontal structural member bridging two or more rafters of a roof to support the deck/roof. The next slide shows a purlin.
This is a photo of joists, a rafter would be the angled beam that supports a steep sloped roof.

7. Example of a PURLIN What’s wrong with this picture? Sub Purlin Purlin
Purlin: A horizontal structural member bridging two or more joists or rafters of a roof.
Point out the main joist in the photo. Most types of decks would never hold without purlins spanning between rafters.
Example of a roof with out purlins is the thick multi board tongue & groove like on gym roofs.
Insulating Deck Boards – wood/glass fibers
Truss Tee Purlins & a slab of gypsum/lt wt concrete
Gypsum: a soft white or gray mineral
What’s wrong with the picture = No Fall protection
Example of “Leading Edge” work.
What’s wrong with this picture?

8. Structural Support
A roof deck successfully should carry these live and dead loads and be able to transfer them to supporting members without significant deflection. Excessive deflection can lead to premature failure of a roof membrane via splitting or degradation caused by ponding. Severe roof deck deflection can potentially contribute to a roof assembly collapse.
Roof-mounted equipment should not rest on the deck or roofing system. It should be supported by the structural framing of the building. Leaks resulting from improperly mounted roof­ top equipment are excluded from roof membrane manufacturer guarantees.

9. FUNCTION Dimensional Stability
A deck also serves as the substrate onto which a roof system is applied. Therefore, a deck should form a dimensionally stable substrate that will not be affected adversely by cyclical thermal and moisture induced movement or other changes that may be expected in a particular environment.
Photos of a concrete deck in need of expansion joint and a deflected deck intended to drain at the wall.

10. Expansion Joint on a Road.
Point out that other trades deal with expansion and contraction but our solutions must be 100% watertight.

11. Dimensional Stability
Decks must Accommodate Building Movement
Snow doesn’t just cause cave-ins but also movement that can cause deflection of deck and too much stress on the membrane.
In Northern climates a lot of hours are spent on snow removal. They sometimes use large hot air blowers to melt as much as possible.
One local 2 contractor removes snow from a roof because the building owner feels it’s cheaper to pay a company to remove snow when it gets to a certain depth than structural reinforcement of the building.
24” of snow = 17 lbs per sq foot
48” = 33 lbs per Sq. foot
72” = 50 lbs per sq foot
Not all snow is the same. 24” of light snow is not the same as dense wet snow. There are winter conditions like large drifts, snow falling onto a deck from a higher elevated roof, shaded area’s that hold snow longer, etc.
In warm climates that never get snow the deck codes are so light that a fall protection cart is classified as too heavy. Most national building codes have a minimum of 20lbs per sq ft. In Southern California where there is no snow this is adhered to. CALOSHA was not recognizing carts as legitimate. An empty cart is close to deck collapse. When pushing a cart over decks in Southern CA you can tell when you’re no longer over a joist. It’s like going up and down small hills.
Other basic load codes are; Promenade 60lbs per sq. foot and green roofs 100 lbs per sq. ft. Where earthquakes are possible seismic loads are calculated in the design.
There are also wind loads and velocity loads taken into consideration when designing deck & roof systems.

12. FUNCTION Fire Resistance
A roof deck should be fire resistant to the degree required for a given building type and its intended use. The greater the degree of fire resistance, the more time the deck is intended to support the roof system during a fire and ultimately provide more time for occupants to escape from the building.
Explain the Detroit auto plant GM fire of 1953 where roofers almost died getting off the one ladder access point. Ask “How many workers on a roof before a second ladder is mandatory”? (25)

13. FUNCTION Attachment Show Ballooned EPDM
For a roof system to perform well throughout its designed service life, its deck should be adequately attached to the structure to resist wind uplift and other forces that the roof assembly may experience.
Some other forces that the deck should be capable of resisting include interior and exterior pressure differentials and lateral loading caused wind and seismic forces.
Show Ballooned EPDM video
Show Ballooned EPDM

14. ATTACHMENT Did this deck stand up to the high winds?
Yes, the insulation delaminated under the force.

15. SLOPE & DRAINAGE
Walls and columns don’t sag while the center of joists sometimes do.

16. SLOPE & DRAINAGE
Slope is provided by:
Sloping the structural framing

17. SLOPE & DRAINAGE Slope is provided by: Sloping the structural framing
Tapered insulation
A deck should slope to provide positive drainage for a finished roof system. The criterion for judging proper slope for drainage is that there is no ponding water on the roof 48 hours after a rain during conditions conducive to drying.
Positive drainage provisions for thoroughly draining a roof area include the correct number, size and placement of roof drains, scuppers or gutters, as well as design of drainage crickets and saddles with sufficiently sloped valleys to assist In drainage of the roof system. A general rule of thumb for designing sufficiently sloping saddles and crickets is that they be twice the slope of the adjacent roof field. This generally will keep water from remaining on the surface of the cricket or saddle.
Designing and installing tapered insulation is expensive and can be complex designs. We will study tapered in a future class.

18. SLOPE & DRAINAGE Slope is provided by: Sloping the structural framing
Tapered insulation
Insulating fills
Expanded Polystyrene (EPS) White board with perforated holes in them.
Pour must be at least 2” thick.
Perforated deck use to be used for drying but now it is dried from the top down.
This is a lengthy process because the concrete must be completely dry before roof application.
Expanded Polystyrene (EPS) 18

19. SLOPE & DRAINAGE Slope is provided by: Sloping the structural framing
Tapered insulation
Insulating fills
Combinations of the
above
This photo illustrates a roof with a combination of structural and tapered crickets/saddle. Explain they both mean the same thing.
We used to call a saddle the chimney back if it tapered to the sides and the low slope a cricket if it tapered around a protrusion or towards a drain/scupper.
Intangibles arise: Tapered system was designed & laid out to accommodate blueprints. The plumber moved a drain because a firewall made it difficult to place the drain where the blueprint described. The contractor fought the G.C. over labor & material but lost. (It was a 100% Union project) Roofers Mart who designed the system ended up paying for it as a public relations gesture although they had nothing to do with the dispute.

20. SLOPE & DRAINAGE

21. DEFLECTION

22. DECK DEFLECTION
Deck deflection should be limited to 1/240TH of the deck's total span to accommodate the stresses of either concentrated or uniform loading. Design and construction personnel should recognize, however, that a roof deck may be subjected to concentrated construction loads. An example of a concentrated construction load is a 200 pound worker carrying 100 pounds of material.
Ever carry a bundle of shingles and hear and feel the sheathing crack when you walked between rafters? You were the concentrated load on a roof not designed for concentrated loads.
Construction loads should be limited to prevent damage to the deck and insulation boards and prevent the loss of attachment between the insulation and deck.
An EPDM ballasted can have rolls up to 50’ X 250’. Ballast can weigh over 1,000 lbs per square (10 LBS PER SQ. FT.). Add the weight of a ballast filled buggy & roofers repeatedly going over isolated spots like the loading area and the insulation can be crushed and the deck deflected.
Ask, “How can this be prevented”? Lay out plywood to protect the area and/or move the loading zone to prevent same area abuse.

23. BUILDING & ROOF MOVEMENTS
Structural decks should not only be able to accommodate thermal cycling and movement of buildings. A deck design should account for the movement of roof system components. Where necessary, building expansion joints and roof area dividers should be designed and installed.
Show video Welcome to Caman1
Video Welcome to Canam1

24. EXPANSION JOINTS
Roof expansion joints are used to minimize the effects of stresses and movements of a building's components and limit the effects of and potential for these stresses to cause splitting, buckling/ridging or damage to a roof system. Expansion joints in the roof assembly should be constructed in the same plane as the building's structural expansion joints, although they also may be required in other locations. Each of the building's components has varying coefficients of expansion and contraction, and each of them is subjected to varying temperature changes and resultant thermal movement. It is the designer's responsibility to allow for building movement and placement of expansion joints during the design of the building and roof system.

25. EXPANSION JOINTS
What should be considered in the design and placement of expansion joints?
The building's thermal movement characteristics
The structural supports and roof deck
The roof system selected
The climatic conditions
Where expansion joints are deemed necessary, both the structural and roof expansion joint should occur in the same plane; they should extend across the entire width of the roof and continue through the roof edge or perimeter. Expansion joints should be designed to accommodate contraction and expansion. For most low-slope membrane systems, expansion joints should be detailed and constructed to a nominal height of 8 inches above the finished roof surface. The use of low-profile expansion joints that are designed to be installed in the horizontal plane of the roof system is not recommended.
With certain single-ply roof membranes capable of extensive elongation, such as EPDM, a below-membrane or concealed type of expansion joint may be applicable in certain climates. However, raised curb-type expansion joints be designed and installed in most geographic locations. Water drainage should NEVER be attempted through or over a raised or low-profile expansion joint.

26. EXPANSION JOINTS Where should we install expansion joints?
Roof expansion joints should be provided at the following locations:
Where expansion or contraction joints are provided in the structural assembly
Where steel framing, structural steel or decking change direction
Where separate wings of "L," "U," "T" or similar configurations exist
Where the type of decking changes; for example, where a precast concrete deck and steel deck abut
Whenever additions are connected to existing buildings
At junctions where interior heating conditions change, such as a heated office abutting an unheated warehouse, canopies, etc. Occasionally, two-piece reglet and counterflashing assemblies can accommodate the movement at main-building-to-canopy intersections.
Wherever differential movement between vertical walls and the roof deck may occur.

27. AREA DIVIDERS Also called ‘Control Joints’ or ‘Relief Joints’
What’s the difference between an expansion joint and area divider?
Slide shows expansion joint on left & Control on right
Control Joint
Sometimes two different types of roof that are not compatible or do not expand and contract the same must join. For example, most single-ply roofing can be damaged by asphalt or pitch. A control joint makes a waterproof connection between the two types so that they do not touch directly. Roof area dividers are raised curbs attached to the structural deck and then properly flashed. If roof area dividers are used, they should be flashed to a minimum height of 8 inches above the roof surface and located at high points in the roof, with drainage away from or parallel to the divider. Roof area dividers should not restrict or impede drainage.
NRCA previously recommended that roof area dividers, be considered for all types of roof membrane systems and recommended that roof area dividers be required for attached and adhered membrane systems at intervals of 150 to 200 feet. These recommendations were based on the experiences of professional roofing contractors working primarily with organic felt (BUR) membranes.
More recently, experience with other types of membranes, such as BUR membranes with fiberglass felts, modified bitumen membranes, and thermoplastic and thermo-set single-ply membranes has proven that roof area dividers may not be required at 150 to 200 foot intervals or may not be required at all. Designers should consider climatic conditions and regional practices and check with membrane manufacturers to determine their recommendations for the necessity of roof area dividers.
An engineer might have designed a building for the old organic felt BUR and placed area dividers every 150 feet. After that roof is replaced with a single-ply the dividers are no longer needed.
It’s easy to confuse area dividers with fire walls. They are basically the same except instead of wood it’s brick or cinder blocks.

28. DECK TYPES The most common types are:
Cementitious wood-fiber deck panels
Lightweight insulating concrete and fills
Poured gypsum concrete
Precast gypsum panel
Steel
Structural concrete (cast-in-place, post-tensioned and precast/prestressed)
Thermosetting insulating fills
Wood-plank and structural wood-panel decks

29. STRUCTURAL CONCRETE
The three general types of structural concrete roof decks are:
Cast-in-place - Concretes that are cast on a job-site over form material and are reinforced with steel bar and/or wire mesh embedded in a deck.
Post-tensioned - Reinforcement cables or tendons are tensioned after the concrete has been cast and taken a set.
Precast/prestressed - Cast at a manufacturing facility and transported to a job site.

30. STRUCTURAL CONCRETE DECKS
Structural concrete that is poured and formed or cast at a job site is referred to as cast-in-place concrete. Common configurations of cast-in-place concrete roof decks are joist and slab or beam and slab, waffle slab, flat plate, flat slab and slab-band.
Structural and lightweight structural concrete are used in constructing cast-in-place concrete roof decks.
Cast in place concrete roof decks

31. POST TENSIONED CONCRETE
(Top illustration) In post-tensioning concrete is not allowed to bond to the steel strands during curing.
(Bottom illustration) After concrete has cured, the strands are tensioned with a hydraulic jack and anchored to the ends of the beam. If the strands are draped, as shown here, higher structural efficiency is possible than the straight strands.

32. PRE-STRESSED CONCRETE
Concrete can withstand large compression forces. However, it is relatively weak against tensile (pulling apart) forces. When a concrete beam or slab is supported only at each end, the weight of a deck and roof could cause it to sag and break at the midpoint, starting at the bottom
Top illustration: Concrete beam will begin to break at the bottom
To make a concrete beam strong enough to carry the weight of a roof, steel cables are added near the bottom of the beam and stretched (Top illustration). The tension on these cables makes the concrete beam strong enough to carry the load of the roof. 32

33. PRECAST/PRE-STRESSED CONCRETE
1. THE FIRST STEP IN PRETENSIONING IS TO STRETCH THE STEEL PRESTRESSING STRANDS TIGHTLY ACROSS THE CASTING BED.
2. CONCRETE IS CAST AROUND THE STRETCHED STRANDS AND CURED.
THE CONCRETE BONDS TO THE STRANDS.
Precast concrete units are poured into forms, typically off a job site, allowed to sufficiently cure, then transported to the site, lifted by a crane, for erection to make up a roof deck. Typically, most precast concrete units are pre-stressed. Pre-stressing is accomplished by pouring concrete around pre-tensioned steel strands set across a casting bed, allowing the concrete to sufficiently cure and bond to the strands. Then, the strands are cut from their anchors outside either end of the cured member. This release of the strands puts the precast concrete member into compression. Pre-stressing generally results in camber, which is an upward deflection, raising the center of the span above the elevation of the supports.
3. WHEN THE STRANDS ARE CUT, THE CONCRETE GOES INTO COMPRESSION AND THE BEAM
TAKES ON A CAMBER ENABLING THE MEMBER TO ACCOMMODATE GREATER LOADING.

34. PRESTRESSED CONCRETE DECK UNITS
HOLLOW CORE SLAB
SOLID SLAB
DOUBLE TEE
SINGLE TEE
Wake up fool & listen to the instructor!
Mr. T

35. Lightweight Insulating Concrete
Expanded Polystyrene (EPS)
Insulating concrete is mixed and poured on the job. It is usually placed over galvanized, corrugated metal. These decks must be at least 2” thick and specially treated to prevent a chemical reaction with the mortar causing the deck to rust.. They must be vented on the top or bottom to allow moisture to escape. The metal base is slotted to provide ventilation from the bottom. Now it is more common to allow the concrete to dry upwards. Expanded Polystyrene (EPS) insulation board with large holes through it is now commonly used with the insulating concrete poured over it at least 2” deep.
Lightweight Insulating Concrete: Standard concrete is made by adding rock, sand, and water to cement.
There are two general types of lightweight insulating concrete roof decks: those made with lightweight insulating aggregates composed of perlite or vermiculite and those using pregenerated foam or other air-entraining agent to form lightweight cellular concretes.
Expanded Polystyrene (EPS)

36. Lightweight Insulating Concrete
Insulating concrete is mixed and poured on the job. It is usually placed over treated galvanized, corrugated metal or EPS with holes. These decks must be at least 2” thick. They must be vented on the top or bottom to allow moisture to escape. Must be a specific type of metal or a chemical reaction will promote rusting. The metal base is slotted to provide ventilation from the bottom. Placing insulating concrete over standard concrete is not recommended. However, if it is used this way, edge vents and small stack vents down to the base concrete must be installed to allow moisture to escape.
Insulating concrete usually provides all the insulation needed. If additional insulation must be added, it must be a special type designed for this type of concrete. Using a board-type insulation is not recommended because of moisture problems.
Insulating concrete can absorb moisture, so it should be protected from the weather until the roof is installed.
It has become more common to allow drying from the top side.
It has a dry density weight of about 24 to 32 pounds per cubic foot.

37. PRECAST CONCRETE
Application for insulated properties as well as a sound barrier for lightweight composite roof or floor deck in commercial, industrial, buildings/structures. This would especially true for power utility problems currently being experienced in hot and cold regions where electricity, gas or oil consumption is an issue. Heating and cooling costs are reduced.
Pre-cast is not pre-tensioned or post-stressed. In
Span capabilities is derived from internal steel tendons embedded in the “legs” of the plank.

38. PRECAST CONCRETE
Hollow core concrete planks advantage of these extrude panels is durability. They offer reductions in sound transmission and can obtain fire ratings of up to 4 hours.
It has very little if any insulation properties.

39. DECK TYPES Cementitious wood-fiber deck panels
Cementitious wood-fiber roof deck panels such as Tectum® are composed of treated course wood fibers that are bonded together with water-resistant cementitous binder, compressed and molded into panels with a pre-finished underside. Structural cementitious wood-fiber panels provide structural support, as well as acoustical (they deaden sound) and thermal insulation. They are sometimes set in place by a crane. The panels are available with tongue-and-groove joints for application directly over joists, mechanical securement to bar joists, and with rabbeted joints for use over subpurlins or bulb tees.

40. Cementitious Wood-Fiber Deck Panels
Lightweight insulating concrete & fills
Cementitious wood-fiber: It is recommended that a base sheet is mechanically attached and the insulation then adhered to the base sheet. If the insulation will be set in hot there should be rosin type paper installed under the base sheet. When possible avoid having insulation joints over the panel joints. It is not recommended the panels have do not have direct contact of hot or modified bitumen.
Specialty fasteners recommended by the manufacturer must be used. Fasteners will be covered in a later class.
Problems have arisen in the performance of roofing systems installed over these deck units. They are:
A. Formation of wrinkles resulting from the accumulation of condensation in the open joints of the deck.
B. Step-downs from slab to slab. These must be leveled off with a screed coat, troweled to a feather edge finish. The screed coat should be of a mix approved by the deck manufacturer, and should extend out onto the surface so as to provide a gradual transition between slabs, where necessary.
C. Sagging or “bowing” of panels over time.

41. DECK TYPES
Cementitious wood-fiber deck panels. Good diagram to explain the definition of a “Bulb Tee”. The grout should be applied evenly. If there are uneven joints they should be grouted also. The grout must be feathered to the slope of the roof.

42. WOOD-PLANK DECKS
A wood-plank roof deck is composed of solid-sawn dimensional lumber. It is normally supported by wood beams, often glued-laminated timber and/or solid lumber joists or purlins. Wood planks may be single-or double­ tongue-and-groove, straight-edged, ship-lapped or grooved for splines on longitudinal edges. Wood-plank decks should have a minimum of 1 inch nominal thickness. The proper thickness of wood planks required for a specific roof is determined by the design loads, including uplift, anticipated for the roof system and distance between supporting members. Wood decks accept fasteners well and the decks are easy to repair if areas become rotted.

43. TONGUE & GROOVE Groove Tongue Bead
Tongue & Groove join together for strength. Some tongue and groove are structural and can be 3 2X 6’s or even larger glued to make a tongue & groove design with the ends also tongue & grooved.
Be careful will fasteners not being too long or adhesives not seeping through. Tongue & groove sheathing usually serves as the buildings ceiling.
Some Tongue & groove is called beaded, this is the design in the center for ascetic purposes only.
Bead

44. WOOD-PLANK DECKS
Shrinkage of planks may be observed where decks have been in service for decades.
Wood Tongue-and-Groove Boards, Planks, and Plywood
Wood was one of the original materials used in roof deck construction and is still widely used because of its economy, ease of application, and appearance .When properly installed, it makes an excellent substrate tor a rooting system. Wood roof decks tend to expand and contract with changes in humidity conditions.

45. PLYWOOD & ORIENTED STRAND BOARD (OSB) DECKS
Plywood Roof Decks: A plywood roof deck is composed of panels made of thin wood layers, veneers, that are peeled from logs. The veneers are laid at right angles to each other then glued together under heat and pressure. This cross-lamination adds strength and stability to the all-veneer panels. Panels consist of a number of cross-laminated layers that vary in number according to the panel's thicknesses.
Oriented Strand Board (OSB) Roof Decks: An OSB roof deck is composed of panels made from layers of com­ pressed, glued wood strands. These strand layers are oriented at right angles to one another before being glued and formed into panels. OSB for roof decks should be a minimum of 15/32 inch thick. The proper thickness of OSB panels required for a specific roof system is determined by the design loads anticipated for the roof system and distance between supporting members. Some plywood OSB come tongue & grooved.
Inspect a wood deck before laying the roof. Clear off all debris and sweep the deck. Repair broken corners, splintered edges, or other damage. Repair any gaps or depressions. All nails should be driven flush. Remove broken or bent nails. Older sheathing may have to be re-nailed. Add new fasteners where needed.
Cover small openings with sheet metal. Be careful not to let hot bitumen drip through the joints. A base sheet, separator sheet, or vapor barrier is mechanically fastened to the wood deck to prevent drips before the BUR is applied.

46. WOOD DECKS
Make sure the plywood is structural. Roof sheathing/decks absorb a lot of heat and can delaminate or not be strong enough to bear loads. Not all plywood is designed for the same purpose.
Disadvantages of wood: burns, rots, insects, dry rot, mold grows, squirrels eat through it, nails back out with movement and puncture through the membrane, plywood can delaminate.
Mold
Fire

47. STEEL DECKS Show: N.J Roofers Falls 40’
Today, steel decks are the most common substrate for commercial/industrial roofing systems and can provide an excellent base for built-up, modified bitumen and single-ply roofing systems, when properly specified and installed.
Metal decking is made of steel sheets formed into channels to provide stiffness. Low front-end cost, versital & labor friendly, and available in many configurations. The metal decking must be secure with welds or screws before the roof is added.
In conjunction with, or in addition to, the Factory Mutual Research Corporation 1-28 and 1-29 requirements, the following guidelines must be followed:
A. Steel deck must be minimum 22 gauge (0.76 mm) and, at a minimum, have a primer coat. Painted or primed steel deck panels exposed to weather may rust at areas where the primer coat has been damaged and at edges that have been cut. Prolonged exposure may affect the integrity of steel roof deck panels.
Galvanized steel deck is recommended.
B. Steel deck units should be welded or, preferably, mechanically fastened to the structural frame, with a minimum of weld holes. Side laps should be fastened with sheet metal
screws on not over 3'-0" (0.91 m) centers.
C. Individual deck units should be flat and without large dents, buckles, or holes. Individual deck pieces should not be more than 1/4" out of plane with one another.
D. Deck openings exceeding 12" x 12" should be reinforced, and wood nailers of the same thickness as the proposed insulation installed, or prefabricated curbs installed, which provide nailing facilities for flashing.
E. A wood nailer must be installed at all roof edges, gables, or curbs, equal in thickness to the proposed insulation and tapered edge strip. Steel decks can bend under heavy loads of roofing material stored on them. To prevent this, lay plywood over the deck where material will be stored. Be sure that the storage area is located over at least two structural members under the deck that will support the weight. Also use plywood to protect the hoisting area and any other heavy traffic areas. Avoid overloading the deck.
Surface Condition Decks should be properly attached, and deck surfaces should be clean and free of upturned edges, sharp burrs and contaminants that may affect proper installation of roof systems.
Insulation should be mechanically fastened to the deck.
Sometimes it’s the environment below the deck that can affect the condition. Show film: “N.J. Roofers falls 40’. A acid container below the deck caused the metal deck directly above it to rust. Non-Union roofers were performing the work on an establishment know to avoid Union Building Trades.
Thanks to Jim Currie Local # 10 Patterson, N.J. for the information on the video.
Show: N.J Roofers Falls 40’

48. STEEL DECKS Flute Flange Flange Rib Rib
70% of Low-Slope roofs are now steel decks, Structural Supports Steel deck panels should be anchored to the supporting members either by mechanical fasteners or welding. Spacing of attachment points is recommend to be no more than 12 inches on center to minimize deck rolling and movement under concentrated, moving rooftop loads.
When the design requires that steel decks be welded, it is recommended that "puddle welds" of ½ inch or larger be welded into steel washers and spaced a maximum of 12 inches on center along every support. Weld burns through a deck should be corrected by the deck installer by mechanically fastening a piece of light­ gauge steel to cover the hole. Deficient welds or mechanical fasteners should be replaced before installing other roof assembly components. Additional supports for steel decks should be provided as required at roof perimeters and penetrations.
Steel deck panels should be installed in a straight line and properly aligned (not spread), as well as squarely intersecting walls and structural framing to facilitate the proper installation of rigid roof insulation. As a guideline for proper alignment of steel deck panels, horizontal variance in the alignment of the panels should not exceed ¼ inch for any 100 feet of roof length.
The 3 most basic parts of a steel deck: flange, rib and flute. A flute is the space between flanges.
The metal decking must be secure before the roof is added.
Rib
Rib

49. STEEL DECKS Rib Width Flange Dimension Rib Depth Web Flute Rib Spacing
Steel roof decks are constructed of cold-rolled steel sheets or panels with ribs formed in each panel to provide strength and rigidity. The panels are available in several gauges, rib depths and flute spacing. Slide describes a description of general steel deck terms and example of a deck profile. NRCA & FM recommends that steel panel roof decks be 22-gauge or heavier and that they have a factory G-90 galvanized coating. Steel decks are generally supported by steel joist framing.
The next four slides display the most common.
Flute
Rib Spacing
Rib

50. STEEL DECKS 30” Approximately 6” 1 ½” Nominal 3/8” Minimum
Example of a narrow rib steel (Type A) deck. A steel deck panel with a rib opening of 1 inch maximum.
3/8” Minimum

51. STEEL DECK 1 ¾” 6” 1 ½” ½” Minimum 30” Nominal
Intermediate-rib steel deck: (Type F) A steel deck panel with a rib-width opening of 1” – 1 ¾”
½” Minimum

52. STEEL DECKS 30” 6” 2 ½” 1 ½” Nominal 1 ¾” Minimum
Wide-rib steel deck (Type B): A steel deck panel with a rib-width opening of 1 ¾” to 2 5/8”
1 ¾”
Minimum

53. STEEL DECKS Approximately 8” 3” Nominal 1 ½” Minimum
Deep-rib steel deck (Type 3DR) A steel deck panel with rib-width opening of 1 ½” inches to 2 ¾” inches, and a rib depth of 3 inches minimum.
These types of steel deck panels also may be available with perforations to provide desirable acoustic properties.
1 ½”
Minimum

54. STEEL DECK REPAIRS
Metal deck panels with multiply openings may require supplemental framing designed by an engineer
Attach plate to deck (4 Fasteners Minimum)
Metal deck repair recommendations: If 1 rib removed no reinforcing needed
Up to 8” diameter removed a minimum gauge plate (15 Gauge) needed.
More than 12” diameter removed then supplemental framing designed by an engineer needed.

55. WOOD NAILERS & CURBS
Wood nailers or curbs should be installed around the perimeter and openings in the roof deck for securement of roofing membranes, edging, gravel stops, and roof fixtures. Nailers should be installed to provide a minimum of 200 lbs. uplift resistance, at any point. A improperly installed wood nailer will allow for wind damage and perimeter failure. The uplift on the perimeter is greater than all other parts.
Nailers should be installed so that the top of the wood nailer is flush with the membrane substrate (which is typically a rigid roof insulation material).
Nailing strips and wood edging or curbs should be of #2 or better lumber. Oil base preservatives such as creosote are not acceptable, as they are not compatible with single ply roofing materials.
Nailers may not be required at perimeters of roof areas that include parapet walls, if an approved securement detail is used to adequately attach the membrane to the wall.
The use of tapered edging strips is recommended to direct water away from roof edges.
Wood nailers should be equal in thickness to tapered edge strips and insulation, and wider than the flange of metal edge strips or gravel stops, to provide adequate nailing.

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