Roofing

Homeowner maintenance includes cleaning the leaves and debris from the roof’s valleys and gutters. Debris in the valleys can cause water to wick under the shingles and cause damage to the interior of the roof. Clogged rain gutters can cause water to flow back under the shingles on the eaves and cause damage, regardless of the roofing material. including composition shingle, wood shake, tile, or metal. The best way to preserve your roof is to stay off it. Also, seasonal changes in the weather are usually the most destructive forces.

A leaky roof can damage ceilings, walls, and furnishings. To protect buildings and their contents from water damage, roofers repair and install roofs made of tar or asphalt and gravel; rubber or thermoplastic; metal; or shingles made of asphalt, slate, fiberglass, wood, tile, or other material. Roofers also may waterproof foundation walls and floors.

Most residential roofs are covered with shingles. To apply shingles, roofers first lay, cut, and tack 3-foot strips of roofing felt lengthwise over the entire roof. Then, starting from the bottom edge, they staple or nail overlapping rows of shingles to the roof. Workers measure and cut the felt and shingles to fit intersecting roof surfaces and to fit around vent pipes and chimneys. Wherever two roof surfaces intersect, or where shingles reach a vent pipe or chimney, roofers cement or nail flashing strips of metal or shingle over the joints to make them watertight. Finally, roofers cover exposed nailheads with roofing cement or caulking to prevent water leakage. Roofers who use tile, metal shingles, or shakes follow a similar process. Some roofers are also water-proof and damp-proof masonry and concrete walls and floors. To prepare surfaces for waterproofing, they hammer and chisel away rough spots, or remove them with a rubbing brick, before applying a coat of liquid waterproofing compound. They also may paint or spray surfaces with a waterproofing material, or attach a waterproofing membrane to surfaces. When damp-proofing, they usually spray a bitumen-based coating on interior or exterior surfaces.

Asphalt is the most commonly used roofing material. Asphalt products include shingles, roll roofing, built-up roofing, and modified bitumen membranes. Asphalt shingles are typically the most common and economical choice for residential roofing. They come in a variety of colors, shapes, and textures. There are four different types: strip, laminated, interlocking, and large individual shingles. Laminated shingles consist of more than one layer of tabs to provide extra thickness. Interlocking shingles are used to provide greater wind resistance. And large individual shingles generally come in rectangular and hexagonal shapes. Roll-roofing products are generally used in residential applications, mostly for underlayments and flashings. They come in four different types of material: smooth-surfaced, saturated felt, specialty-eaves flashings, and mineral-surfaced. Only mineral-surfaced is used alone as a primary roof covering for small buildings, such as sheds. Smooth-surfaced products are used primarily as flashing to seal the roof at intersections and protrusions, and for providing extra deck protection at the roof’s eaves and valleys. Saturated felt is used as an underlayment between the roof deck and the roofing material. Specialty-eaves flashings are typically used in climates where ice dams and water backups are common. Built-up roofing (or BUR) is the most popular choice of roofing used on commercial, industrial and institutional buildings. BUR is used on flat and low-sloped roofs and consists of multiple layers of bitumen and ply sheets. Components of a BUR system include the roof deck, a vapor retarder, insulation, membrane, and surfacing material. A modified bitumen-membrane assembly consists of continuous plies of saturated felts, coated felts, fabrics, or mats between which alternate layers of bitumen are applied, either surfaced or unsurfaced. Factory surfacing, if applied, includes mineral granules, slag, aluminum, or copper. The bitumen determines the membrane’s physical characteristics and provides primary waterproofing protection, while the reinforcement adds strength, puncture resistance, and overall system integrity.

Concrete tiles are made of extruded concrete that is colored. Traditional roofing tiles are made from clay. Concrete and clay tile roofing systems are durable, aesthetically appealing, and low in maintenance. They also provide energy savings and are environmentally friendly. Although material and installation costs are higher for concrete and clay tile roofs, when evaluated on a price-versus-performance basis, they may out-perform other roofing materials. Tile adorns the roofs of many historic buildings, as well as modern structures. In fact, because of its extreme durability, longevity, and safety, roof tile is the most prevalent roofing material in the world. Tested over centuries, roof tile can successfully withstand the most extreme weather conditions including hail, high wind, earthquakes, scorching heat, and harsh freeze-thaw cycles. Concrete and clay roof tiles also have unconditional Class A fire ratings, which means that, when installed according to building code, roof tile is non-combustible and maintains that quality throughout its lifetime. In recent years, manufacturers have developed new water-shedding techniques and, for high-wind situations, new adhesives and mechanical fasteners. Because the ultimate longevity of a tile roof also depends on the quality of the sub-roof, roof tile manufacturers are also working to improve flashings and other aspects of the underlayment system. Under normal circumstances, properly installed tile roofs are virtually maintenance-free. Unlike other roofing materials, roof tiles actually become stronger over time. Because of roof tile’s superior quality and minimal maintenance requirements, most roof tile manufacturers offer warranties that range from 50 years to the lifetime of the structure.

Concrete and clay tile roofing systems are also energy-efficient, helping to maintain livable interior temperatures (in both cold and warm climates) at a lower cost than other roofing systems. Because of the thermal capacity of roof tiles and the ventilated air space that their placement on the roof surface creates, a tile roof can lower air-conditioning costs in hotter climates, and produce more constant temperatures in colder regions, which reduces potential ice accumulation. Tile roofing systems are made from naturally occurring materials and can be easily recycled into new tiles or other useful products. They are produced without the use of chemical preservatives and do not deplete limited natural resources.

Single-ply membranes are flexible sheets of compounded synthetic materials that are manufactured in a factory. There are three types of membranes: thermosets, thermoplastics, and modified bitumens. These materials provide strength, flexibility, and long-lasting durability. The advantages of pre-fabricated sheets are the consistency of the product quality, the versatility in their attachment methods, and, therefore, their broader applicability. They are inherently flexible, used in a variety of attachment systems, and compounded for long-lasting durability and watertight integrity for years of roof life. Thermoset membranes are compounded from rubber polymers. The most commonly used polymer is EPDM (often referred to as “rubber roofing”). Thermoset membranes make successful roofing materials because they can withstand the potentially damaging effects of sunlight and the most common chemicals generally found on roofs. The easiest way to identify a thermoset membrane is by its seams, which require the use of adhesive, either liquid or tape, to form a watertight seal at the overlaps. Thermoplastic membranes are based on plastic polymers. The most common thermoplastic is PVC (polyvinyl chloride) which has been made flexible through the inclusion of certain ingredients called plasticizers. Thermoplastic membranes are identified by seams that are formed using either heat or chemical welding. These seams are as strong or stronger than the membrane itself. Most thermoplastic membranes are manufactured to include a reinforcement layer, usually polyester or fiberglass, which provides increased strength and dimensional stability. Modified bitumen membranes are hybrids that incorporate the high-tech formulation and prefabrication advantages of single-ply with some of the traditional installation techniques used in built-up roofing. These materials are factory-fabricated layers of asphalt, “modified” using a rubber or plastic ingredient for increased flexibility, and combined with reinforcement for added strength and stability. There are two primary modifiers used today: APP (atactic polypropylene) and SBS (styrene butadiene styrene). The type of modifier used may determine the method of sheet installation. Some are mopped down using hot asphalt, and some use torches to melt the asphalt so that it flows onto the substrate. The seams are sealed by the same technique.

Are You at Risk?

If you aren’t sure whether your house is at risk from natural disasters, check with your local fire marshal, building official, city engineer, or planning and zoning administrator. They can tell you whether you are in a hazardous area. Also, they usually can tell you how to protect yourself and your house and property from damage. It is never a bad idea to ask an InterNACHI inspector whether your roof requires repair during your next scheduled inspection. Protection can involve a variety of changes to your house and property which that can vary in complexity and cost. You may be able to make some types of changes yourself. But complicated or large-scale changes and those that affect the structure of your house or its electrical wiring and plumbing should be carried out only by a professional contractor licensed to work in your state, county, or city. One example is fire protection, accomplished by replacing flammable roofing materials with fire-resistant materials. This is something that most homeowners would probably hire a contractor to do.

Replacing Your Roof

Some roofing materials, including asphalt shingles, and especially wood shakes, are less resistant to fire than others. When wildfires and brush fires spread to houses, it is often because burning branches, leaves, and other debris buoyed by the heated air and carried by the wind fall onto roofs. If the roof of your house is covered with wood or asphalt shingles, you should consider replacing them with fire-resistant materials. You can replace your existing roofing materials with slate, terra cotta, or other types of tile, or standing-seam metal roofing. Replacing roofing materials is difficult and dangerous work. Unless you are skilled in roofing and have all the necessary tools and equipment, you will probably want to hire a roofing contractor to do the work. Also, a roofing contractor can advise you on the relative advantages and disadvantages of various fire-resistant roofing materials.