Document Sample
					Roof covering materials

                   Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [1]
Roof covering materials


This report would not be complete, had it not been for a lot of assistance from a lot of sources. I
take this as an opportunity to extend my gratitude to all of those who have contributed to the
completion of this report in any manner large or small.

We are especially grateful to our subject teacher Ar. Sandeep Mishra whose remarkable
enthusiasm and valuable words were instrumental in our perceiving things in a logical manner
and formulating a direction for this project. We must also thank for their indispensable and
accurate guidance through each stage. We also like to thank our respected HOD Prof. S.H.H
Naqvi and Er. Anupam Verma for their help throughout the report and seminar.

We would also like to all my friends and junior who helped us in our seminar and report to make
it successful, without their help and support it wouldn’t be.


                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [2]
Roof covering materials


    This report presents the knowledge of the types of roof and the roofing material based on the
    latest specification. The basic type of roof covering and modern roof covering is explained
    by an ample number of figures. This report will help the readers to update him/her about
    various types of roof covering and it’s laying process. A preliminary knowledge of the
    different type of roof structure is required before going through this report.

    We are thankful to Ar. Sandeep Mishra in guiding us in making up of our report and
    presenting seminar. We are also thankful to Er. Anupam Verma and some of our juniors for
    their kind cooperation.

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.      [3]
Roof covering materials

    1- Roofs
      1.1 Introduction
      1.2 Parts of roofs
      1.3 Classification of roofs
      1.4 Industrial roofing
    2- Roof covering materials
      2.1 Introduction
      2.2 History of roof covering material
      2.3 Various types of roof covering materials
      2.4 For flat roofs –
               2.4.1 Roll roofing
                 2.4.2 Membrane roofing
                 2.4.3 Built –up roofing
      2.5 For pitched roofs –
                2.5.1 Wood
                2.5.2 Asbestos Cement Sheets
                2.5.3 Asphalt Shingle
                2.5.4 Slate
                2.5.5 Tile
                2.5.6 Metal Roof
                2.5.7 Corrugated Aluminum Sheets
      2.6 New roof covering materials
                2.6.1 Polymers

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [4]
Roof covering materials

               2.6.2 Sequentia Corrugated Roof Panels
               2.6.3 Polycarbonate Sheets
               2.6.4 P.V.C. roofing sheets
    3- Types of roof coatings
    4- Roof slope
    5- Insulation in roofing
    6- Ventilation
    7- Drainage system
    8- Fixing materials

                            Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [5]
 Roof covering materials

A Roof is the covering on the uppermost part of a building. A roof basically consists of roof
covering materials supported on structural elements installed on building top. The structural
elements may be trusses, portals, flat slab, shell, dome or space frame. Whereas the roof covering
material may be thatch, wooden shingle, tiles, slates, A.C. sheets, G.I. sheets etc.

 A well planned roof should be –

        Structurally sound.
        Durable against adverse effects of elements like rain, snow, sun, wind.
        Efficient water proofing & drainage systems.
        Provide desirable insulation against heat & sound.
        Reasonably priced.
        Aesthetically attractive

 Parts of a roof - There are two parts to a roof, its supporting structure and uppermost
 weatherproof layer. In a minority of buildings, the outer layer is also a self-supporting structure.

 The elements in the design of a roof are:-

        the material

                                 Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [6]
Roof covering materials

        the construction
        the durability

The material of a roof may range from banana leaves, wheaten straw or sea grass to laminated
glass, aluminum sheeting and pre cast concrete. In many parts of the world ceramic tiles have
been the predominant roofing material for centuries.

The construction of a roof is determined by its method of support and how the underneath space
is bridged and whether or not the roof is pitched. In regions where there is little rain, an almost
flat roof with a slight run-off provides adequate protection against an occasional downpour.

The durability of a roof is a matter of concern because the roof is often the least accessible part
of a building for purposes of repair and renewal, while its damage or destruction can have
serious effects.

Basic Terminology:
1) Roof: the entire covering assembly
2) Roofing: that part of the roof which is exposed to the elements.
3) Pitch: rise over run
4) Substrate: the decking that carries the roofing material.
5) Eaves: roof overhangs
6) Ridge: the peak of two or more roof slopes
7) Valley: an inverse ridge
8) Ceiling: the finish material attached to the underside of the roof.

Classification of roofs –
    1) Flat or Terraced Roof
    2) Pitched or Sloped Roof

Flat roof –
Properties -

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [7]
Roof covering materials

1) A roof is designated as flat id its slope is less than ten degrees.
2) Flat roofs have traditionally been used in hot climates where water accumulation is not a
3) They were generally unknown in northern climate before the end of the last century.

Advantages of flat roof:
1) No space lost below roof, i.e. no dead space
2) Less material is used than in a sloped roof
3) The rooftop is potentially useful as a terrace, or sleeping porch
4) Potentially pleasing appearance
5) Easier to build than a sloped roof

Disadvantages of flat roof:
1) Roof elements can not overlap, hence waterproofing must be more complex, and more
2) Drainage is not automatic
3) Support of snow load must be insured

Pitched roof –        it is the cheapest alternative for covering the structure. This is generally
constructed in wood or steel the pitch is the angle at which the roof rises from its lowest to
highest point. Most domestic architecture, except in very dry regions, has roofs which are sloped,
or pitched. Example thatch, require a steep pitch in order to be waterproof and durable. Other
types of roofing, for example pan tiles, are unstable on a steeply pitched roof but provide
excellent weather protection at a relatively low angle.

Advantages –

       These are light in weight.
       It can be used for long span without introduction of the intermediate supports.
       Drainage is automatic.
       Leakages can be easily detected.
       These roofs are preferable in heavy rainfall and snowfall area.
       Easy to install and rapid in construction as there is no need of formwork.
       Pitched roofs can be insulated to create either warm or cold roof spaces.

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.      [8]
Roof covering materials

       The basic design principle in the pitched roof is that by overlapping materials in the down slope
        direction, and by providing a waterproof surface, water will not sit, but will be forced to rub off
        the roofing surface.
       Comparatively low maintenance required.
       Creates attractive and interesting exteriors.

Disadvantages –

       Noisy
       Thermal insulation is not better as of flat roof.
       Roof top is not accessible.
       It cannot resist heavy wind pressure.
       Being softer these sheet are more likely to tear away in heavy storm.
       Having greater thermal expansion results in noisy creaks and more stress on fasteners.
       It cannot be used in multi-storied buildings.

Industrial roofing – In industrial roofs we generally use pitched roof due to its long spans
without intermediate columns, light weight, easy installation, better drainage system etc.

                     ROOF COVERING MATERIALS –
    Selection of roofing material depends on –
    •   The roof shape, type of structure and slope determine the types of roofing material that
        are suitable. The minimum slope on which a material can be used depends on exposure to
        the wind, type of joint and overlap, porosity and the size of the unit.

                                  Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.               [9]
Roof covering materials

    •   When considering the cost of various roofing materials, it should be noted that those
        requiring steeper slopes will need to cover a greater area. Table in next page provides a
        guideline for the relative increase in roofing area with an increase in slope. The area for a
        flat roof has been taken as 100.

    •   The weight of the roof covering material greatly influences the design of the roof
        structure and the purling. Table 5.12 shows some examples.

History of roof coverings – The earliest roof used readily available materials from
the surrounding terrain and needed to be portable. Most likely the first roof was covered with
dirt, underplayed with branches and supported by wooden beams.

                                          The Sod Roof system is one the original "Green
                                          Roofs" and one of the oldest flat roofing systems
                                          know. Dirt roofs might be the oldest flat roofs ever
                                          made. Although Sod Roofs are ancient in design,
                                          early American settlers in the Great Plains used this
                                          design in the 1800's.

    Over 30,000 years ago, Aborigines used bark from birch trees for their roofs. But in places
like Siberia where birch trees were not available, hunter gathers used mammoth skins to cover
their dwellings .

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [10]
 Roof covering materials

 Mammoth Skins are one of the oldest roofing materials known to mankind. The whale
 skin huts would have been similar in design.

               More advanced civilizations used thatch and reeds to build dwelling roofs. The
 dwellings were more permanent structures but were designed to be easily dismantled because of
 spring floods. Later these dwellings became permanent when built on piled or rock foundations.

     Rice straw thatch                                Roofed with banana leaves.

  The Thatch Roof dates back to around 30,000 BC. This style of roof is still
 being used in parts of Africa where climates although for use of such housing.

Natural    asphalt     was     first   used       as     early   as     30,000      BC      as     a
waterproofing technique, something that is still used today. Ceramic tiles, another familiar roofing
product, was created around 10,000 BC by the Chinese and shortly after in the Middle East.

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [11]
Roof covering materials

Clay Tile roofs are the oldest roofing product to still be used today. The Chinese developed
Clay baked tiles around 10,000 BC. Shortly after Clay Tiles were produced in the Middle

Various types of roof covering materials –
There are an enormous variety of roofing materials; selection is based on price, durability,
appearance, roof slope –

    For low slope and flat roofs -

            ROLL ROOFING
            MEMBRANE
            BUILT-UP


            Traditionally used for low-slope
             residential work.
            Available in single and double coverage.
            Very inexpensive, but considered unattractive
            Applied with nails and tar, tar typically leaks out at edges

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [12]
Roof covering materials


          “Rubber” roofing (EPDM) and other similar materials come in sheets or rolls, are
           glued or ballasted to the roof, and seams are heat or solvent welded.
          Materials are relatively expensive, but roof is long lasting and stays flexible.


            Multiple layers of felt and tar applied to a roof deck, and then the surface is
       covered with ballast.
            Labor intensive, nasty materials, and dangerous work, but it used to be the only
      way to get a waterproof flat roof

                            Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.     [13]
Roof covering materials

For pitched roofs, roof covering materials are:
           WOOD
           SLATE
           TILE
           METAL

                       Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [14]
Roof covering materials


            Shakes are rough surface (hand split or
             similar) and provide heavy shadow lines
            Shingles are sawn and are used for siding as
             well as roofing
            Cedar shingles are the most common, they
             are expensive and must be treated with fire


    The advantages of asbestos-cement sheets (A-C) are:

        Longer life if properly fitted
        Less noise from heavy rain and thermal
        More attractive
        Better thermal insulating properties

    The disadvantages are:

           They are heavier - (the weight per square
           meter is more than twice that of GCS) thus it
           is more expensive to transport and requires a
           stronger roof structure.

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [15]
Roof covering materials

          Brittleness causes a high rate of waste due to breakage during transport and
          installation. A more rigid roof structure is necessary as the sheet does not allow for
          more than very small movements of the supporting structure without cracking.
          Walking on the roof may also cause cracking.
          Labor intensive due to weight and brittleness.
          The corners of the sheets must be mitered prior to fitting and holes for the fixing
          screws must be drilled.
          Easily discolored with dust and algae.
          The manufacture and processing of asbestos products presents hazards to health

Laying process of A-C sheets -

           Corrugated A-C roofing should be installed with a slope of 1:2.5 (22°) and an end
            lap of at least 150mm under normal conditions. Under exposed conditions a
            200mm end lap is better. The sheets are designed for a side lap of half a
            corrugation in all situations.

           Purlins must be of sawn timber in order to provide a flat support for the sheets and
            must be designed with a minimum of deflection. For the type of sheets described
            here, a maximum purlin spacing of 1.5m is recommended. If used as wall
            cladding the spacing can be increased to 1.8m.

           Sheets should be laid from left to right or right to left depending on the direction
            of the prevailing wind. Side laps must always be sheltered from the main wind

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [16]
Roof covering materials

MITRING - The correct mitre is most important. This should be made from a point along the
edge of the sheet equivalent to the end lap, i.e. either 150mm or 200mm, to a point along the end
of the sheet equivalent to the side lap 47mm. The gap between the mitres should be at least 3mm,
but not to exceed 6mm. The sheets can be Cutwith a handsaw or a sheet hacksaw.

      Holes must be drilled 2 to 3mm larger than the diameter of the roofing screws to be used to
allow for movement within the framework of the building and the sheets themselves. All holes
must be on the crown of the corrugation. It is important to remove all drilling dust before
washers are put in position, otherwise water may be allowed to penetrate. Screws should be
finger-tight until the correct alignment of the sheets in relation to the purlin has been checked.
They should then be tightened until some resistance is felt. Screws should be located in the
crown of the second and fifth corrugation of a sheet of seven corrugations. All end laps must
occur over the purling .

     ASPHALT SHINGLE - There are two kinds of asphalt shingles on the market:
    Fiberglass shingles and organic-mat shingles. Fiberglass shingles are thinner, lighter, and easier
    to lug around, and carry a better fire rating than organic shingles. Organic-mat shingles are

                                 Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [17]
Roof covering materials

    tougher and stay more flexible in cold weather. Fiberglass shingles predominate in southern
    and central regions, but organic shingles are still popular in the North and are almost the
    universal choice in Canada. In practice, organic shingles have a much higher tear strength and
    nail-pull resistance than fiberglass shingles.


         Felt or fiberglass substrate, impregnated with asphalt
         Mineral surface sprayed on surface
         Adhesive seal-down strips at midpoint.
         Multiple layers in architectural (built-up) shingles
         Relatively low cost and easy to install
         Good fire resistance (usually Class A)


       Asphalt shingles are an economical versatile roofing solution.
       They're relatively inexpensive to buy and install, are suited to roof pitches from 4-in-12
        to vertical.
       Available across a wide range of quality, cost, and style.

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.       [18]
Roof covering materials

     Easy to cut, fit, and fasten, asphalt shingles are compatible with many different kinds of
      flashing and edging products.
     They don't require specialized accessories for roof edges, wall terminations, chimney or
     Shingle must resist abrasion from elements, degradation from UV, loss of asphalt due to
      drying (heat), etc.
     Shingles carry warranties of 15 to 40 years depending on the amount of material used to
      make the shingle. Weight per square varies accordingly.

     Metal shakes or shingles. Long life. High cost, suitable for roofs of 3/12 pitch or greater.
      Because of the flexibility of metal, they can be manufactured to lock together, giving
      durability and reducing assembly time.


           Sheathing is installed with H clips
           Drip edge installed on eave under underlayment
           Underlayment “15 lb felt” is used as initial waterproof barrier, and separation
            between roof deck and roofing
           Waterproof underlayment is used for lowest 36” to extend inside of eave 24”
           Drip edge installed over underlayment on rake edge

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [19]
Roof covering materials

    o SLATE-

            A very long-lasting roof, and quite expensive.
            Roof framing must be reinforced for the weight
            Slate should not be walked on if old
            Can be repaired with clip, normally fastened
             with copper nails in pre-drilled holes

      TILES –
            Clay and Cement tiles used very commonly in warmer climates.
            Roof framing must be reinforced
            Applied with mortar or using nails
            Traditionally applied over purlins, nailed to sheathing today

                            Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [20]
Roof covering materials

        Recent improvements in paint quality and life have brought more painted steel
          roofs into the residential market.
        Cost competitive with asphalt shingles, and longer lasting, used commonly for
          agricultural structures
        Attached with gasketed nails or more commonly with gasketed screws
        Long life & durability.
        Lightweight
        Popular for low and steep-slope roofs
        Often receives cosmetic damage from hailstorms, but Class 4 product rated for
       impact resistance are available
        Product available with Class A fire rating
        Standing-seam metal with concealed fasteners.
        Mechanically seamed metal with concealed fasteners contains sealant in seams for
          use on very low sloped roofs.
        Flat-seam metal with soldered seams.
        metal roof can withstand just about all the harsh weather Mother & metal roof
          retains its good looks and performance for years.

       Types of metal sheets -

        Galvanized corrugated steel sheets - frequently manufactured with wavy
         corrugations to resist lateral flexing and fitted with exposed fasteners. Widely
         used for low cost and durability. Sheds are normally roofed with this material.
         Known as Gal iron or Corro, it was the most extensively used roofing material of
         20th century Australia, now replaced in popularity by steel roofing coated with an
         alloy of zinc and aluminum, claimed to have up to four times the life of
         galvanized steel.

                          Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.     [21]
Roof covering materials

The main advantages of GCS are:

          The relatively light weight makes the sheets easy to transport and flexible so they
         are not easily damaged during transport.
          It is easy to install and handle. However, the edges of the sheets are often very
         sharp and can cause cuts in clothing and skin. The sheets may be cut to any required
         length and the roofing nails can be driven through the sheets directly without drilling
          The supporting structure can be relatively simple. Due to the flexibility of the
         sheets, minor movements of the supporting structure can occur without damage.
          The sheets are quite durable if maintained and are not attacked by termites or
         fungus. They are water-tight and non-combustible.
          They can be dismantled and reused provided that the same nail holes are used.

The main disadvantages of GCS are

          The main disadvantages of GCS are its poor thermal properties and the noise
           caused by heavy rainfall and thermal movements. The thermal and sound
           properties are improved by an insulated ceiling.
          Most corrugated steel sheets have corrugations with a 76mm pitch and 19mm
           depth. Thickness varies between 0.3-1.6mm of which 0.375-0.425mm are
           recommended for farm buildings.

      Standard widths normally marketed are 610, 762mm and 1000mm. Lengths range from
      2 to 4m.

                            Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [22]
Roof covering materials

         Recommendations for Slope, End Lap and Side Lap for Corrugated Steel Roofing

Type of position              min                min end lap                 min side lap
Sheltered site                1:5                150mm                       1.5 corrugation
                              1:3                100mm                       1 corrugation
Normal site                   1:3                100mm                       1.5 corrugation
Exposed site                  1:3                150mm                       2 corrugation

Laying process –
      The spacing of the purlins will depend on the thickness of the sheets used. As a guide,
      maximum spacing of purlins for 0.475mm sheets is 1500mm. The purlins should be a
      minimum of 50mm in width in order to be easily nailed.
      The laying of the sheets should commence from the eave and away from the prevailing
      wind. The side laps will then be away from the wind preventing water from being forced
      into the lap.

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.          [23]
Roof covering materials

    It is very important that the first sheet be
    laid at right angles to the eave and the ridge
    for by so doing; all the rest will also be
    perpendicular with the ridge. The first row of
    sheets is laid with a 50mm overhang beyond
    the facie board.


    CA sheets are lighter and more durable than GCS sheets, but are more expensive. When
    new, the sheets have a bright reflective surface, but after a year or more oxidation of the
    surface will reduce the glare. There is never any need to paint aluminum sheets for
    The reflective surface will keep the
    building cooler than with GCS sheets, but
    since aluminum is softer, the roof is more
    likely to tear away in a heavy wind storm.
    Aluminum also has a greater thermal
    expansion than steel resulting in noisy
    creaks and more stress on fasteners.
     CA sheets are normally supplied with
    the same corrugation and in the same sizes
    as GCS. For use in farm buildings, a
    thickness of 0.425mm is recommended. The sheets are laid and fixed in the same manner
    as GCS.

                             Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [24]
Roof covering materials

Invisible to most people, roofing materials have undergone a dramatic transformation during the
last decade or two. Certainly, the quest for lower cost and better performing buildings has
influenced roofing material requirements.

o POLYMERS - The use of polymers has played a large part in enabling the fulfillment of
these requirements for bituminous roofing materials. Bituminous waterproofing has been re-
invented to become

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.      [25]
Roof covering materials

            an advanced,
            proven,
            reliable
             resilient waterproofing material
            it is fit for purpose over a large climatic temperature range,
            Exhibits longevity and is user-friendly during application.

Kraton polymers have been at the forefront of this revolution, with their first application in
roofing felts in the early seventies. Kraton Polymers continues to push the boundaries providing
solutions for developing challenges.

       These versatile plastic panels make excellent roofs allowing filtered light through
        but keeping the elements at bay.
        These are reinforced with gloss fibers (FRP, fiberglass reinforced panels) will
        expand and contract up to three times less than PVC and polycarbonate panels
       It is a more stable product in both hot and cold conditions.
       Panels install much like corrugated metal and provide the added benefit of light


              Polycarbonate panels contain a translucent UV
         resistant film on only one side of each panel.
              Each polycarbonate panel is imprinted with the
               following: “THIS SIDE OUT”.
              The side of the panel with this information should
               be installed toward the sun or exterior of the
               structure it is being used on. The other side of the
               panel has little UV resistance and will be damaged
               by the harmful rays of the sun.
              Polycarbonates panels are not recommended as
               exterior privacy walls (which are installed
               vertically vs. horizontally) because both sides of
               the panel can receive direct exposure to the sun
               hence, damaging the panel.

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.      [26]
     Roof covering materials

                   These are manufactured in varied thickness, ranging form 1.0mm to 2.5mm.

          These sheets are suitable for roofing of Industries, warehouses, poultry and dairy farms,
         stud farms, farm houses, weather sheds, parking lots, terrace
         gardens and in host of other applications.

          These sheets are also manufactured as translucent sheets for the
         sky lighting application in all the aforesaid profiles which are very
         useful in providing natural light in Industries, warehouses or for
         that matter any installation where the natural light in inadequate.
         This also results in power saving and reduces the lighting cost

     Salient Features of PVC Roofing Sheets –

    Excellent corrosion resistance - these are the best as regards the corrosion resistance. In corrosive
    atmospheres like high acidic vapors in chemical plant / picking plants, high carbon and carbon monoxide
    emission in industrial belts and also in urban areas due to automobiles exhaust, high salt content weather
    prevailing in coastal areas etc., our sheets are the best suited

   Rust Proofness – In humid weather, metallic sheets get rusted and the Asbestos sheets tend to soften due
     to absorption of moisture. These sheets do not absorb any moisture, nor do they get rusted.
   Thermal insulation –there is a sizable difference in temperatures ‘above the roof’ and ‘below and roof’.

                                    Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.       [27]
       Roof covering materials

        This is possible because these sheets reflect the heat into the space above the roof and whatever little
        heat is absorbed the same is not passed on to the inner spaces of the structure. Due to these thermal
        insulation properties sheets are ideal in applications like poultry farms. Cow sheds, stud farms or
     Maintenance –maintenance free as they do not require any painting, or any other maintenance. Also these
      sheets do not absorb dust or moisture. This helps in maintaining the gloss and the texture of the sheets.
     Light Weight – Density of material being only 1.4, it is light in weight compared to other roofing material
    an available in the market. Due to this, transportation and fabrication of material is easier. Carrying the
    material to high rise buildings becomes easy. Also due to light weight there is a saving on structural cost.
     Fire Retardant Properties – these sheets have fire retardant properties and they do not propagate the fire.

     Hygiene – Our material is suitable for foodstuff and hence, is preferred for food industry or wherever
     hygienic roof is required. This is not the case with other roofing material like Asbestos, Asphaltic or
     metallic sheets. Sustenance of Seismic Tremors / earthquakes – this material being flexible is capable of
     sustaining the seismic tremors / earthquakes. In contrast, the asbestos sheets being brittle can not sustain
     earthquakes. The metallic sheets also get deformed and can break in case of severe earthquakes.

     UV Protection –sheets are UV protected and hence they do not warp with exposure to sunlight, nor does
     the color fade

                                                             Width    Net
           Profile                              Pitch Depth                  Thickness
                            Profile                         Trimmed Coverage
           Name                                 (mm) (mm)                      (mm)
                                                             (mm)    (mm)

                                                 250     40      1054      1000      1.8-2.5
           Greca                                                                                 OF
                                                  76     18      1045       988      1.0-1.5     ROOF
            ron                                                                                  NGS -
                                                  76     18      1086      1010      1.0-1.5

                                      Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [28]
 Roof covering materials

 coating has become an effective and popular method of extending the life of a roof. It can add
 protection against weather and fire may increase energy efficiency and can even be used to
 change a roof’s color. Roof coatings should be applied before any serious roof deterioration

 Maintenance roof coatings or cold process roof coatings are ready-to-use protective coatings for
 roofs Roof coating professionals generally use coating materials that can be grouped into the
 following five categories:

 Asphalt-Base Coatings: Asphalt-Base Coatings come in three different types: emulsion, solvent
  or aluminum pigmented.

 • Emulsion Type Coating – it is adaptable over asphalt built-up roofs, metal roofs and those
 similarly composed, provided there is adequate drainage. When applied in the proper thickness,
 it chalks slowly and doesn’t blister. It can be applied over a damp surface and will not flow
 under heat. It does require temperature and humidity conditions that permit thorough water
 evaporation before the coating can be subjected to rainfall, freezing, or standing water. Emulsion
 coating requires a clean and a primed surface for good adhesion.

 • Solvent Type Coating it can be applied over asphalt, composition, asbestos-cement, metal and
 masonry roof surfaces. It can be applied on a clean, dry surface over a wide temperature range
 and is relatively free of wash-off problems after a short drying period. It has good water
 resistance and may not require a primed surface for good adhesion.

 • Aluminum Pigmented Coating - It can be applied over asphalt, composition or metal roofs
 having adequate drainage and provides a reflective or decorative surface. The coating’s
 reflectivity helps improve buildings energy efficiency by deflecting ultraviolet rays and reducing
 the roof’s temperature...

  Alky-Base Coatings: Alkyd-base coatings can be applied over metal, composition or masonry
 roofs that have adequate drainage. They perform the same functions as aluminum pigmented

  • Acrylic Latex Coating: it is available in various colors. White and other light colors reflect
 the sunlight, keeping the interior of a building cooler and conserving energy during warmer

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [29]
Roof covering materials

• Refined Coal Tar Coating: Refined coal tar coating is used for re-coating tar and gravel roofs

• Flexible Ceramic Coating: Flexible Ceramic Coating is a relatively new addition to the roof
coating business. The primary attraction of a ceramic coating is its insulation properties that
allow for energy efficiency. As a result of its flexible nature, ceramic coatings help seal cracks
and hide surface flaws. It has proven particularly popular in warmer climates.

Roof Slope-
Roof slope is a very important aspect and it is considered the primary factor in roof design. The
slope of a roof has an effect on the interior volume of a building, the drainage, the style, and the
material you use for your covering.

The slope of a roof is often referred to as the pitch. The slope, or pitch, of the roof is determined
by the vertical rise in inches for every horizontal twelve inch (12") length (called the "run"). A
roof with x rise/12 run slope means that for every 12 inches horizontally (run), it rises x inches.
Below are some of the common roof slopes and the terms which classify them.

       Flat Roof: 2/12
       Low Slope: 2/12-4/12
       Conventional Slope Roof: 4/12-9/12
       Steep Slope: 9/12 and higher

Steeper sloped roofs are generally more visually pleasing and tend to last longer as well.
However, they also cost more because a steep sloped roof requires a taller chimney and more
lumber for framing. On average, a 12/12 roof can cost up to 50% more than a roof with a 4/12
slope. Many find that it is worth it though because the roofing material is estimated to last up to
50% longer and will require less maintenance in the long run.

Lastly, roof slope helps determine the appropriate materials for the roof. A roof with a 4/12 pitch
will allow products such as shingles or tiles. According to roof covering material angle, slope,
and rise is given below in the table:

Minimum Pitch Requirements for Roofing Materials –

                                Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.          [30]
Roof covering materials

                   Roof Covering                       Angle    Slope        Rise in mm/m
Built-up bitumen felt                                   3°       1:20                 50
Corrugated metal sheets (min. 150end laps)              12°       1:5             200

Corrugated metal sheets (min. 100 end laps)             18°       1:3             300

Corrugated asbestos cement sheets with 300mm            10°      1:5.7            180
end lap
Corrugated asbestos cement streets with 150mm          22.5°     1:2.4            410
end lap
Single lap tiles                                        30°      1:1.7            580
Plain tiles in burnt clay                               40°      1:1.2            840
Slates min 300mm wide                                   25°      1:2.1            470
Slates min 225mm wide                                   35°      1:1.4            700
Shingles (wood)                                         35°      1:1.4            700
Thatch of palm leaves (Makuti)                          34°      1:1.5            670
Thatch of grass                                         45°       1:1             1000

Insulation in roofing –

The purpose is to insulate against heat and cold,
noise, dirt and often from the droppings and lice of
birds who frequently choose roofs as nesting

Position of insulation
There is a choice of insulation position in
pitched roofs:

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [31]
Roof covering materials

                At rafter level
                Between the rafters
                Above and between the rafters
                Below and between the rafters
                At ceiling level

Other forms of insulation are felt or plastic sheeting, sometimes with a reflective surface,
installed directly below the tiles or other material; synthetic foam batting laid above the ceiling
and recycled paper products and other such materials that can be inserted or sprayed into roof


    Attic areas, or just dead areas in the roofs constructed of trusses,
    are generally provided with ventilation systems to allow in outside
     Vents are generally located under the eaves, at the gable ends,
    at the ridge, or by fans.
     Soffit and ridge must be opened
     When ridge and soffit can not be opened, gable end vents, or
    pan vents can be used
     Two main reasons for keeping the attic at outside temperature
    are as follows:
                   a) Summer heat
                   b) Winter humidity

The Aura Solar Attic Fan uses both solar and wind power, for an optimum ventilation
performance both day and night. Other solar powered attic fans do not move air passively, but
the Aura Solar Attic Fan does, just like a roof turbine ventilator, but with no moving parts.

                                 Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.        [32]
Roof covering materials

Continuous Rain Guttering, Also known as Seamless Guttering "Seamless Gutters" is nationally
recognized as the most popular form of guttering. Seventy-
five percent of all guttering installed throughout the nation
is continuous. Its popularity is easily understood because...

       Continuous Rain Guttering, Seamless Guttering,
        eliminates unsightly seams
       Reduces the possibility of leaks
       Baked on enamel finish never needs painting
       Protects the beauty of your home and landscaping
       Formed on the job site for exact measurements
       Most jobs are completed in one day                            “K” – style gutter
       Many colors from which to choose from

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [33]
Roof covering materials

the purpose of guttering systems is to collect water (rain)
from the roofing area and disperse the water away from your
home. Properly configured downspouts (leaders, drain
pipes) are very essential. A faulty guttering system can
contribute to damage to Soffit & Fascia, Shingles, Building
Foundations, Driveways, Walkways, Landscaping.

Seamless Gutters
There are many different gutter materials to choose from,
including steel, aluminum, vinyl, copper. Many types of
gutters (steel and vinyl in particular) are sold in 10’ lengths and Half round style gutter
require dozens of seams fastened with slip fittings, each one is
a weak spot and a potential leak site. Another alternative well worth considering is the
installation of seamless aluminum gutters. Seamless gutters must be fabricated on-site by a
professional contractor.

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [34]
Roof covering materials

                        Gutter detail

FIXING                                                                         MATERIALS

Typical Fasteners include weatherproof nails or wood screws with Neoprene washers, self-
tapping screws and grommet type fasteners. Fastener selection is dependent upon type of
corrugation and understructure material. Panels should be pre-drilled a minimum of 1/16" larger
than fastener diameter.

                              Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.      [35]
Roof covering materials

                                     One touch fastener

    Positioning of the fasteners –

       1. Position the first panel and use temporary fasteners at the corners, if needed, to square
    the panel on the framing. If necessary, trim ends to center panels on the framing.
       2. Install fasteners at one panel end.
       3. Remove fasteners at corners.
       4. Install intermediate fasteners, starting at the panel's edge. Use a chalk line or straight
    edge to align fasteners on the framing. Fasten panels in rows across the width, continuing this
    sequence along the length of the panel.
       5. To ensure contact with the framing while fastening the panel, stand over the framing
    near the fastener location. (Standing between framing while nailing can lock sag into the roof
    sheathing.) Drive fasteners flush with the panel's surface.
       6. Leave 1/8 inch of space between adjacent panels ends and edge joints unless a panel
    manufacturer recommends otherwise. For a spacing tool, use an 8d common or 10d box nail,
    or panel edge clips.
       7. After sheathing is in place, you can easily saw-cut or kerf out any tight joints you might
    have missed. The saw blade will give you the 1/8-inch spacing you need. Kerfing, however,
    must be done before any buckling occurs because once buckling has occurred, the panels will
    retain a “memory” of the buckle and not flatten out completely.
       8. For improved performance, use thicker sheathing panels, panel edge clips, or panels
    with tongue-and-groove edges. Check local building codes before using panel edge clips
    since requirements depend on the relationship between a panel's span rating and the actual
    distance between framing members.

     This is the best procedure we've found for securely fastening roof panels and minimizing the
    effects of stress build-up during their expansion.

                               Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.         [36]
Roof covering materials

NUTS &                                                                BOLTS

                   Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [37]
Roof covering materials



                   Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [38]
Roof covering materials

Sushil Kumar - Building Construction

S.C Rangawala – Building Construction


Company templates.

Indian standard

Ching – Visual dictionary.


                             Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [39]
Roof covering materials

Asbestos cement corrugated sheet………14

Asphalt shingle………………………….16

Advantage of pitched roof………………07

Advantage of flat roof…………………..07

Built-up roofing…………………………12


Corrugated aluminum sheets……………23

Clay tile………………………………... 10


Disadvantage of pitched roof……………08

Disadvantage of flat roof………………..07


Flat roof…………………………………06

Fixing detail……………………………..35


Galvanized corrugated steel sheets. ……..20


                            Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [40]
Roof covering materials

Laying……………………………………15, 18, 22

Metal roof sheet………………………….19

Mitring …………………………………..15

Membrane roof…………………………..12

Nuts and bolts……………………………37

Thatch roof………………………………10

PVC sheet………………………………..25

Polycarbonate sheet……………………...25


Pitched roof………………………………07


Roll roofing……………………………….11


Sequentia corrugated roof panels…………25


Types of ventilator………………………..32


Wood shake and shingle…………………..14

                         Department of Architecture, B.B.D.N.I.T.M., LUCKNOW.   [41]

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