Moisture Protection

Roofing

Roofing materials provide the water-resistant covering for a roof system. They range in form from virtually continuous, impervious membranes to overlapping or interlocking pieces of shingles and tiles. The type of roofing that may be used depends on the pitch of the roof structure. While a sloping roof easily sheds water, a flat roof must depend on a continuous waterproof membrane to contain the water while it drains or evaporates. A flat roof as well as any well-insulated sloping roof capable of retaining snow may therefore have to be designed to support a greater live load than a moderately or high-pitched roof.

Additional factors to consider in the selection of a roofing material include requirements for installation, maintenance, and durability, resistance to wind and fire, and, if visible, the roofing pattern, texture, and color.

Roof Slopes

Roof pitch or slope is the angle of the roof surface above the "flat" or horizontal plane.

1. Sloping Roofs

Sloping roofs may be categorized into

- Low-slope roofs—up to 3:12- Medium to high-slope roofs—

4:12 to 12:12- The roof slope affects the

choice of roofing material, the requirements for underlayment and eave flashing, and design wind loads.

- Low-slope roofs require roll or continuous membrane roofing; some shingles and sheet materials may be used on 3:12 pitches.

- Medium and high-slope roofs may be covered with shingles, tiles, or sheet materials.

- Sloping roofs shed rainwater easily to eave gutters.- The height and area of a sloping roof increase with its horizontal dimensions.- The space under a sloping roof may be usable.- Sloping roof planes may be combined to form a variety of roof forms.

2. Flat Roofs

- Flat roofs require a continuous membrane roofing material.

- Minimum recommended slope: 1/4" per foot (1:50)

- The roof slope may be achieved by inclining the structural members or roof deck, or by tapering the layer of thermal insulation.

- The slope usually leads to interior drains. Secondary, emergency overflow roof drains or scuppers are required in cases where water might be trapped if the primary roof drains are blocked.

- Flat roofs can efficiently cover a building of any horizontal dimension, and may be structured and designed to serve as an outdoor space.

Components of a Sloping Roof System

1. Roof deck — a roof deck is the structural substrate and usually made of wood sheating(plywood or oriented strand board), steel, concrete or compact asphalt fills.

2. Underlayment — underlayment provides temporary protection until a roof covering is installed and provides a secondary weatherproofing barrier. Sometimes underlayment is referred to as "felt" or "paper."Types of Underlayment

Asphalt-saturated Felt Rubberized Asphalt Non-bitumen Synthetic

3. Roof covering — the roof covering is the external water-shedding material.Types of Roof Covers

Wood Shingles and Shakes Composite Shingles Tile Roofing Slate Shingles Metal Roofs Corrugated Roof

Types of Underlayment

1. Asphalt-Saturated Felt

- One of the most common types of underlayment used in residential, steep-slope applications is black, ashphalt-saturated felt paper. Felt underlayment may be made from either organic or fiberglass substrate

- Felt underlayment is water-resistant, but not waterproof.

- It is cheaper compared to others

2. Rubberized Asphalt

- Various types of rubber-like materials are also used as underlayment and are generally referred to as “rubberized asphalt.” These typically have adhesive on one side, which is protected by a peel-off membrane, making them self-adhering. The rubber-like qualities of these underlayments make them self-sealing, meaning that they seal well around fasteners, such as staples and nails.

- They may be formulated for use in high-temperature situations. This allows them to be installed under metal roofs an in harsh environments.

3. Non-bitumen Synthetics

- Non-bitumen synthetic underlayments are made from polypropylene or polyethylene. These synthetic polymers are also used to make a huge variety of other types of products, from food-storage containers and rope, to long underwear.

- Synthetics are resistant to fungal growth and are wrinkle-free, since they don’t absorb moisture. They’re also very resistant to UV damage and can be left exposed to weather for periods from six months to a year.

Types of Sloping Roof Cover

1. Wood Shingles and Wood Shakes

- Wood shingles and shakes are normally cut from red cedar. Red cedar has a fine, even grain and is naturally resistant to water, rot, and sunlight.

- Wood shingles are sawn. - Wood shakes are formed by

splitting a short log into a number of tapered radial sections, resulting in at least one textured face.

- Wood shingles are normally 100% clear heart wood (The older, nonliving central wood of a tree or shrub, usually darker and harder than the younger sapwood).

- Helps to insulate the attic, and it allows the house to breathe, circulating air through the small openings under the felt rows on which wooden shingles are laid.

- Demands proper maintenance and repair, or it will not last as long as other products. Mold, rot, and insects can be a problem. The lifecycle cost of a shake roof may be high, and old shakes can't be recycled.

- Requires spray-on fire retardants or pressure treatment to resist fire.

2. Composite Shingles

- Composition shingles have either an inorganic fiberglass base or an organic felt base surfaced on the weather side with colored mineral or ceramic granules.

- Composition shingles are a good choice for a clean look at an affordable price. Higher-quality versions made from asphalt or fiberglass shingles offer a more durable option and may be available with recycled content.

- Composition shingles come in a large selection of types, brands and colors. Versatile, they adapt easily to different applications.

- They are relatively easy to install, and in some applications can be nailed in place over an existing roof. They require low maintenance and can be walked on without damaging the material.

- On the negative side, they can blow off in high winds. Material is easy to scar if hot. Does not have the dimensional look of tile or shake.

3. Tile Roofing

- Tile roofing consists of clay or concrete units that overlap or interlock to create a strong textural pattern.

- Roofing tiles are fire-resistant, durable, and require little maintenance.

- They are also heavy and require roof framing that is strong enough to carry the weight of the tiles.

- Roofing tiles are normally installed over a solid plywood deck with an underlayment.

- The advantages of concrete roofing vary from product to product, but generally they all have a long lifespan, require low maintenance, offer good fire protection and are resistant to rot and insects.

- Concrete is more expensive than some roofing materials

4. Slate Shingles

- Slate is an extremely durable, fire-resistant, and low maintenance roofing material. Slate shingles are split, trimmed, and drilled to receive copper nails or wire ties.

- A fine-grained rock formed by the metamorphosis of clay, shale, etc., that tends to split along parallel cleavage planes.

- Although slate is an expensive choice, it offers a very natural look and can be laid out in a variety of patterns.

- Have a very long lifespan, good fire protection, low maintenance, and an

invulnerably to rot and insects. It comes in a good selection of sizes and colors, although colors are limited to those found in nature.

- Like tile, slate can be very heavy, sometimes requiring expensive extra support. It is breakable enough that walking on it is difficult for a non-professional, complicating such tasks as rooftop maintenance, gutter cleaning and painting.

5. Metal Roofs

- A sheet metal roof is characterized by a strong visual pattern of interlocking seams and articulated ridges and roof edges.

- The metal sheets may be of copper, zinc alloy, galvanized steel, or terne metal, a stainless steel plated with an alloy of tin and lead.

- To avoid possible galvanic action in the presence of rain water, flashing, fastenings, and metal accessories should be of the same metal as the roofing material. Metal roofing can be installed over existing roofs, eliminating the need to dispose of excess material in a landfill.

- Installing some metal roofing can be an intricate process best done by a professional, and the initial cost of a premium metal roof is higher than most other roofing materials. You need to compute the lifecycle cost to see if paying more to begin with for a metal roof will prove to be a better investment than some other form of roofing.

Different Types of Seam

- There are many categories of metal panels. The term standing seam often is used as a generic description for a class of metal roof seams. The name standing seam is derived from the fact that the seams are joined together above the panel flats. The term also is used to refer to a panel profile that includes a standing seam: the vertical leg/flat pan and the trapezoidal seam. The trapezoidal standing seam is more commonly associated with structural metal panels. Other panel types are batten, flat, bermuda and shingled.

- The original batten seam consisted of vertical leg panels placed between wood batten strips and covered with a cap. Today, many batten seam panels are constructed entirely of metal. Because they are designed to shed water, batten seam panels primarily are used in architectural applications.

6. Corrugated Roofs

- Corrugated or ribbed roofing panels span between roof beams or purlins running across the slope. The roofing panels may be of:• Aluminum with a natural mill or enameled finish• Galvanized steel• Fiberglass or reinforced plastic• Corrugated structural glass

- Corrugated roofing started out as sheet metal. They form some sort of waves on the roofing for design as well as for purpose.

- Nowadays corrugated roofing is made from different materials, such as Stainless Steel, Fiberglass, Aluminum, Coated or Painted Steel.

- Usually they are treated with special finishes to prevent corrosion. Corrugated roofing materials are easy to use and install.

- Corrugated roofing materials are widely used in the Philippines- Steel corrugated roofing materials can be quite long lasting. They are also

pretty lightweight and easy to handle. - Corrugated roofing materials that uses fiberglass are very translucent

which can provide natural lighting to the house or building. They are watertight and are very lightweight and durable.

- Corrugated roofing materials are also more rigid than a flat sheet of a similar type and thickness, this results to a substantial reduction in cost and weight.

- The corrugated roofing materials sheets can also be very heated during hot sunny days and the heat can radiate to the rest of the structure making it very uncomfortable.

Flat Roof Assemblies

1. Built-Up Flat Roofs

- A built-up roof, most of the time referred to as BUR, is a time-tested roofing system typically comprised of hot tar and gravel.

- It is made up of many layers and typically the top layer is where the tar and gravel lie. This is a system that has been around and in demand for ages.

- It is also a very strong roofing system which allows it to be more useful as it can handle more foot traffic and other structures on the roof surface.

- Of all the flat roof options available today, BUR has been around the longest.

- The reinforcing fabrics also are called roofing felts or ply sheets. Roofing felts are reinforced with either glass-fiber mats or organic mats.

- Surfacings for built up roof systems include aggregate (such as gravel, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings.

2. Modified Bitumen Flat Roofs

- Modified Bitumen roofs are two-ply systems that are most often roll-applied to the roof surface.

- They are similar to asphalt roofs but they have additional polymers in their materials that provide added protection from the elements and help in increase the lifespan of the product.

- These are the least popular flat roofing system discussed, but are still pretty common and have a good reputation.

- Many times, Modified Bitumen roofs are installed by rolling out the roofing material after it has been heated with a blow torch. The heating process allows the material to adhere to the roof surface.

- Surfacings for built up roof systems include aggregate (such as gravel, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings.

3. PVC Roofing System

- PVC is a type of single-ply membrane system. This roofing system is highly reflective and very durable.

- PVC is one of the top flat roof options because it is easy to install and lacks water permeability, meaning it can resist water ponding.

- The problem with PVC, and the biggest difference from roof coatings, is that it is applied in rolls, and therefore it has seams that can lead to roof failure. When it is rolled out, these seams must be taped or glued together. While this may resist water for a while, it will not hold up for 10-15 years as a seamless roofing system would.

4. EPDM Flat Roofs

- EPDM, which stands for Ethylene Propylene Diene Monomer, is a synthetic rubber derived from oil and natural gas.

- It is a single-ply system that is very similar to PVC, but it is rubber while PVC is plastic.

- The EPDM roofing system has grown over the last few decades on the strength of its reputation as a durable, inexpensive roofing option. These traits have spurred its growth and have made it the most common commercial flat roof choice in the US today.

- It is also revered for its quick installation.

5. Spray-Applied Roof Coating

- Specifically, silicone roof coating systems.

- These are the roofing systems that we apply, and we believe they are the best because of their seamless application (sprayed on), ability to resist ponding water, and reflective properties.

- As the roof reflects the sun, it helps to reduce energy consumption inside the building.

- These roofs are also extremely sustainable, as a new roof can be applied over top of most substrates, including on top of our own substrate, meaning no operations inside the building must stop for application.

- The downside of this system is cost, which is expected for a system that provides such high quality and so many features. Silicone roof coatings are typically one of the top two most expensive roofing solutions, depending on the roof layout and the specific situation.

Roof Drainage

Roof drains is a type of drain installed to receive water collecting on the surface of a roof and to discharge it into a leader, downspout, or conductor. The amount of rain or melting snow a roof and its drainage system must handle is a function of:

• The roof area leading to the roof drains or gutters• The frequency and intensity of the rainfall for the region

Flat roofs should be pitched to roof drains that are located at the low points and that connect to the storm drain system of the building. A system of Scuppers or overflow drains may also be required with the inlet flow 2" above the low points of the roof.

Rainwater shed by sloping roofs should be caught by gutters along the eave to prevent ground erosion. Gutters empty into vertical downspouts or leaders that, in turn, discharge into a dry well or storm sewer system. In dry climates or for small roof areas with adequate overhangs, gutters may be omitted and a bed of gravel or a masonry strip set in the ground under the eave line.

Gutters are typically of vinyl, galvanized steel, or aluminum, although copper, stainless steel, and wood ones are also available. Aluminum gutters can be cold-formed on-site in continuous runs without joints.

Flashing

Flashing refers to thin continuous pieces of sheet metal or other impervious material installed to prevent the passage of water into a structure from an angle or joint. Flashing generally operates on the principle that, for water to penetrate a joint, it must work itself upward against the force of gravity, or, in the case of wind-driven rain, it would have to follow a tortuous path during which the driving force would be dissipated.

Flashing may be exposed or concealed. Exposed flashing is usually of a sheet metal, such as aluminum, copper, painted galvanized steel, stainless steel, zinc

alloy, or copper-clad lead. Metal flashing should be provided with expansion joints on long runs to prevent deformation of the metal sheets. Flashing concealed within a construction assembly may be of sheet metal or a waterproofing membrane such as bituminous fabric or plastic sheet material, depending on climate and structural requirements.