Roofing is responsible for several important functions. Most importantly, it serves as the structural support of your home. In addition, the roof controls water ingress, air flow, water vapor diffusion, heat flow, and offers surface protection. However, in order for a roof to function properly, the right roof materials and components in the assembly must be selected based on the properties that make them suitable for these various tasks.

Before you think about which material to use, decide if you really need a new roof. Do a roof inspection. Look for:

  • Loose, warped or worn roofing material.
  • Excessive roofing granules in the gutters (from shingle roofs).
  • Discolored paint or peeling wallpaper inside the house (indicates the presence of moisture).
  • If you find any of these, then you may soon need a replacement roof. Roofing can be a daunting task. First decide whether you wish to do-it-yourself or hire a contractor.

Roof leaks are not always the sign of a failed roofing system. You may not actually need a new roof. Loose or missing shingles and many flashing problems can be easily repaired.

Roofing Price

The price of a new roof system varies widely, depending on such things as the materials selected, contractor doing the work, location, local labor rates and time of year. It is important to keep in mind that for each roofing material, there are different grades and corresponding prices. There also are a variety of roof styles and shapes to choose from. You need to look at the full product range and make a choice based on your budget and needs.

Types of Roofing

Composition Shingle

The most widely used roofing material is the composition shingle. Commonly known as asphalt shingles, they come in two types, differentiated by the base material. They consist of either an organic fiber mat or fiberglass core. Each type is impregnated with asphalt and coated with mineral granules to add color and texture. An adhesive back combined with nails, tacks or staples is the fastening method used. You will most likely find a “good/better/best” selection. Compare warranties (number of years the roof should last) when shopping. Shingles are available in the common 3-tab style or newer architectural designs that replicate other roofing materials such as wood or slate.

Corrugated Sheet

There are two main types:

  • Sheets composed of fiber and impregnated with asphalt are available in many colors (or can be painted). This sheet roofing can be installed over existing roofs of other types. This is one of the easiest roofs to install for a do-it-yourselfer.
  • Sheet roofing made from translucent fiberglass or PVC.

Wood

There are two types. Shingles are cut to a specific size and smooth finished. Shakes are irregular and rough-textured. Wood gives a natural look to a home. It also requires more maintenance to protect it from the elements. Wood roofing is commonly made from cedar. Fire-resistance is definitely a consideration in some areas due to local ordinances.

Metal

Metal roofs have returned from the olden days to become a popular roofing option. Once limited to low-slope structures, standing seam steel roofs can now be used on steeper roofs as well. Metal is durable, practically maintenance-free, heat reflective and nonflammable. Installed in sheets, a metal roof will actually dissipate a lightning strike rather than conduct it (a concern left over from the olden days). For real visual impact, a copper roof ages to an attractive patina.

Built-up Roofing

Built-up roofs are installed on flat or very low-sloping structures. They consist of alternating layers of felt or fiberglass treated with asphalt. These layers are topped with asphalt (tar) or aggregate. Built-up roofs are more common in commercial buildings.

Tile and Slate

These are two of the oldest roofing materials around. They are long-lasting and durable. Their weight requires a reinforced roof structure that can support them. Both can be quite expensive and neither are easy to install.

Factors That Affect Roofs

  • Sun delivers a combination of ultraviolet rays and heat can prematurely age a roof.
  • Snow or ice that melts and refreezes (called ice damming) pushes up the roofing material and causes leaks. Ice damming can be a temporary problem that ends when the thaw is complete. Excessive amounts can damage the roof and roof structure.
  • Rain is normally kept at bay by a roof. But when rain or moisture gets underneath roofing, damage can occur.
  • Wind can remove any roof in the most extreme occurrence. However even minimal amounts can weaken a poorly installed roof by letting dirt and moisture get underneath.
  • Moisture from condensation underneath a roof not only harms the roof and sheathing, but also can cause problems inside of the house.
  • Trees provide shade to help cool a house. They also provide leaves and limbs that can fall or scrub against the roof.

Algae and moss get a foothold on moist surfaces. Excessive growth can retain moisture and cause eventual weakening of the roofing material.

Whichever Roofing Material You Choose:

  • Repair structural problems before installing a new roof. Troubles caused by factors such as improper or damaged sheathing and roof trusses and poor drainage will only resurface in the new roof if not dealt with.
  • Not all roofing materials can be used on steep-slope structures. Know your slope before you go shopping.
  • Pick colors to complement the rest of the home.
  • Look for the fire rating. The scale is rated A, B or C. The A rating is the most fire-resistant, C is the least.
  • Roofing treated with zinc or copper particles for algae resistance is a good idea in humid climates.
  • Proper ventilation to prevent condensation is critical to an efficient roofing system.
  • Adequate insulation also increases a roof’s efficiency.
  • Local building codes may dictate roof types and, as in shingle roofing, mandate how many layers may be installed before a complete replacement is required.

Compare warranties when shopping. Actual roof performance will depend greatly on installation, climate and maintenance.

Roofing Shapes

There are many different distinct shapes for roofs these days, some more common than others. We have provided our users with a list of the most popular roofing shapes today and some details about their appearance and construction.

  • Gabled – Constructed with a single slope on each side of the ridge, creating a triangle portion on the side of front facade.
  • Side-Gabled – Non-gabled side faces the front and contains the front doorway.
  • Front-Gabled – Gabled side faces the front and contains the front doorway.
  • Cross-Gabled – Perpendicular wings are added to the main section forming two individual sections with their own gabled facade.

Important Aspects of Roof Assembly

Roof Insulation: Insulation controls heat flow both into the building and out of the building. There are many different types of thermal insulation that are used in roofing. Keep in mind that moisture resistance is an important property to consider when selecting roof insulation because water has a much higher thermal conductivity than air. Insulation options include cellular glass, polystyrene, polyurethane, polyisocyanurate, phenolic foam (air filled/gas filled), wood fiber board, and mineral fiber.

Vapor Barriers: The vapor barrier is responsible for limiting diffusion of moisture from inside the building into the roof assembly. Generally the vapor barrier is located on the warm side of the thermal insulation so that its temperature will not fall below the dew point temperature of the inside air. This is how condensation in the roof is controlled. There are several different materials to choose from.

Top Cover: The top covers are responsible for protecting the underlying roof components from UV radiation and physical damage. They come in several types including liquid applied coatings, factory applied mineral and metal surfaces, gravel and pavers. Keep in mind, liquid applied coatings require a certain amount of maintenance. Also, gravel and pavers are more resilient but have the disadvantage of adding to the vertical load on the structure.