Roof

Roof

Types of roof structure

Pitch roof Flat roof Space frame Roof shell Folded plate Membrane

A pitched roof

column

wall

columns

walls

A mono-pitched roof structure

A lean-to roof structure

column

wall

columnwall

flashing

openings

SUNSHADING

Steep roof

Roof with a pitch of 3:12 (25 percent) or greater

PITCHED ROOF: TIMBER - truss

STEEL - truss

Truss built as from individual members

Truss fabricated from factory

Truss fabricated from factory

Whole roof structure built fromsteel

Gang nails

steel

rivetted

Placement of roof clay tiles as seen from below

Roof components

SECTION OF ROOF STRUCTURE

PITCHED ROOF

TIMBER O

R STEEL RAFTER

Waterproofinglayer andinsulation

Timber batten

Finishes:Clay tiles orCement tilesMetal decking

Ceiling

STRUKTUR KAYU &

KELULI Waterproofing layer

Timber batten

Insulation layer

Finishes:Clay tiles orCement tilesMetal decking

Ceiling

Roof finishes – steep roof

Asphalt shingles –mostly of petroleum Slate-quarried stone and concrete tiles Metal roofing materials

ROOF FINISHES

ATTAP

CLAY ROOF TILES

PATTERNED STEEL DECKING 1

PATTERNED CLAY ROOF TILES

PATTERNED STEEL DECKING 2

ASBESTOS

2. Flat roof A roof is designated as flat if its slope is

less than ten degrees. Flat roofs have traditionally been used

in hot climates where water accumulation is not a problem.

They were generally unkown in northern climated before the end of the last century

Flat roof Slope less than 3:12 or 25 percent Structural decks ordinary used

Wood panels over wood joist Solid wood decking over heavy timber framing Corrugated steel decking Sitecast concrete slab Precast concrete slab Panels of wood fibre bonded together with

portland cement etc

Flat roof

The decks be adequately stiff under roof loading and uplift forces

The decks must slope towards drainage points

A slope at least ¼ “ per foot run (1:50) is recommended

Flat roof If the slope is too shallow, puddles of water

will stand for extended periods Leading to premature deterioration of the

roofing materials in those areas If water accumulates cause by structural

deflection, progressive structural collapse becomes possibility

Deepening puddles attracting more and more water and becoming heavier

a) Water stands on the roof in puddles, causing slight deflections of the roof deck between supporting beams or joists

b)If heavy rain continues, the puddles grow and joint. Accumulating weight of the water begins to cause substantial deflections. Deflection encourage water from a border area of the roof run into the puddle

c) As structural deflection increase, the depth of the puddles increases more and more rapidly, until the overloaded structure collapses

a

b

c

CONCRETE, TIMBER OR STEEL STRUCTURE

Waterproof layer andinsulationCement screedFinishes

FLAT ROOF

Flat roof

Thermal insulation Below the structural deck Between the deck and the membrane Above the membrane

Below the deck

Between the deck

Above the membrane

ELEMENTS OF FLAT ROOF

parapet

Concrete gutter

Steeldecking

parapet

Lines indented for expansioncaused by heat and easy to flattenthe roof in a uniform manner to prevent any pool of water after rain.

concrete

Water pool formed due topoor workmanship

PROBLEMS OF LEAKING ON FLAT ROOF

Weatherproofing the flat roof

The flat roof relied on some kind of membrane for keeping moisture out. In dry climates this is done with clay tiles, but in Canada asphalt, or rubber is necessary.

Flat roofs are never actually flat, a subtle slope directs standing moisture to drains at edges, or inside.

Flat roof

Advantages of flat roof design: No space lost below roof, i.e. no dead

space Less material is used than in a sloped roof The rooftop is potentially useful as a

terrace, or sleeping porch Potentially pleasing appearance Easier to build than a sloped roof

Disadvantages of flat roof design: Roof elements can not overlap, hence

waterproofing must be more complex, and more thorough

Drainage is not automatic Support of snow load must be insured

Flashing Flashing is special material used to make sure

that no moisture leaks in those areas of a roof that are particularly vulnerable to penetration.

Areas where flashing is commonly used: Wherever the roof is pierced by a chimney,

skylight, air or plumbing vent Where roofs meet walls At the edges of flat roofs where they meet

parapet walls (a wall that extends above the level of the roof)

Flashing Materials from which flashing is made of:

Galvanized metal Aluminum Copper Building paper

Flashing Design: Sloped roofs: it is important to design flashing so that it

throws the water downslope, and does not rely on mastic. Flat roofs: it is important that flashing be extended above

the level at which you expect snow or water to accumulate

3. Space frame

A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames usually utilize a multidirectional span, and are often used to accomplish long spans with few supports. They derive their strength from the inherent rigidity of the triangular frame; flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut.

Dome

Dome

4. ROOF SHELL

5. FOLDED PLATE ROOF

6. MEMBRANE

6. MEMBRANE

Roof insulation The most cost-effective Increase occupant comfort by moderating the

radiant temperature of ceilings and walls Reduce heating and cooling energy Cellulose insulation- most environmentally

friendly thermal insulating material Glass wool and mineral fibre Polystyrene foam made from petroleum Polyurethane foam insulation

New concepts of roof

Final products

PROFILED STEEL SHEET DRY BOARD ROOF SYSTEM (PSSDB)

The profiled steel sheet Dryboard The profiled steel sheet Dryboard panel is a composite structural panel is a composite structural system consisting of profiled steel system consisting of profiled steel sheeting/decking compositely sheeting/decking compositely connected to dryboards by simple connected to dryboards by simple mechanical connectorsmechanical connectors..

Structural components of

PSSDB System

COMPONENTS OF PSSDB AJIYA CLIP & LOCKING CL 660 ---A profiled steel

sheet product of Ajiya Roofing products, Malaysia.

PRIMAFLEX---A top grade cellulose fibre, Portland

cement and finely ground sand produced by Hume

Cemboard Berhad, Malaysia.

SCREWS---Self-tapping, self-drilling screws.

Main Advantages of the System

Lightweight Rapid construction Dry construction technique Easily assembled by unskilled labour Saving in foundation cost of the buildings Less deep than the traditional timber joist flooring Less loading to existing structure in renovation work No propping/formwork required during construction No waiting period for occupation after the completion of

construction.

MAIN APPLICATIONS OF PSSDB PANEL

❍ The profiled steel sheet dryboard system The profiled steel sheet dryboard system can be exploited for various structural can be exploited for various structural purposes such as:purposes such as:i)i) Flooring units. Flooring units.

ii) Walling units.ii) Walling units. iii) Panels may be assembled to form iii) Panels may be assembled to form

Folded Plate Folded Plate Structures such as as roofs of Structures such as as roofs of buildings.buildings.

❍ The normal position is not suitable to be used in real The normal position is not suitable to be used in real buildings.buildings.

❍ Show slight softening in strength and bulging in volume Show slight softening in strength and bulging in volume under wet condition.under wet condition.

❍ Even though a water proofing can be used from directly Even though a water proofing can be used from directly exposed to the hot and dry weather, but it is not a exposed to the hot and dry weather, but it is not a practical in practicepractical in practice

❍ Based on the original concept of the system, the Based on the original concept of the system, the application has been extended to form a new concept of application has been extended to form a new concept of roofing system.roofing system.

❍ The new approach will eliminate the roof trusses The new approach will eliminate the roof trusses normally required in traditional roof structure. normally required in traditional roof structure.

PSSDB Roof system

Erection of roof panels

Erection of roof panels

Completed classroom modules

Side elevation

Back elevation

A SITE ENGINEER SENT THIS TO THE DESIGNER: Sub: High Priority Steel roof and column already constructed, kindly send us the foundation drawings. Site people can construct any thing, so please be careful with your drawings. Please send foundation drawings before superstructure drawings

Regards, Site Engineer