Roofing explained  and How Maintaining Helps

Roofs play a key role in protecting building occupants and  interiors from outside weather conditions, primarily moisture. The roof,  insulation and ventilation must all work together to keep the building free of moisture. Roofs also  provide protection from the sun. In fact, if designed correctly, roof overhangs  can protect the building’s exterior walls from moisture and sun. The concerns  regarding moisture, standing water, durability and appearance are different,  reflected in the choices of roofing materials.

Maintaining Your Roof

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.
There are two types of roofs:  flat and pitched  (sloped). Most commercial, industrial and apartment buildings have flat or  slightly sloping roofs. Most houses have pitched roofs. Some roofers work on  both types; others specialize. Most flat roofs are covered with several layers  of materials. Roofers first put a layer of insulation on the roof deck. Over the  insulation, they then spread a coat of molten bitumen, a tar-like substance.  Next, they install partially overlapping layers of roofing felt, a fabric  saturated in bitumen, over the surface. Roofers use a mop to spread hot bitumen  over the surface and under the next layer. This seals the seams and makes the  surface watertight. Roofers repeat these steps to build up the desired number of  layers, called plies. The top layer either is glazed to make a smooth finish or  has gravel embedded in the hot bitumen to create a rough surface. An increasing  number of flat roofs are covered with a single-ply membrane of waterproof rubber  or thermoplastic compounds. Roofers roll these sheets over the roof’s insulation  and seal the seams. Adhesive mechanical fasteners, or stone ballast hold the  sheets in place. The building must be of sufficient strength to hold the  ballast.
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 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.
A number of roofing materials are available…Asphalt
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.
Metal

Most metal roofing products  consist of steel or aluminum, although some consist of copper and other metals.  Steel is invariably galvanized by the application of a zinc or a zinc-aluminum  coating, which greatly reduces the rate of corrosion. Metal roofing is available  as traditional seam and batten, tiles, shingles and shakes. Products also come  in a variety of styles and colors. Metal roofs with solid sheathing control  noise from rain, hail and bad weather just as well as any other roofing  material. Metal roofing can also help eliminate ice damming at the eaves. And in  wildfire-prone areas, metal roofing helps protect buildings from fire, should  burning embers land on the roof. Metal roofing costs more than asphalt, but it  typically lasts two to three times longer than asphalt and wood  shingles.
Wood

Wood shakes offer a natural  look with a lot of character. Because of variations in color, width,  thickness, and cut of the wood, no two shake roofs will ever look the  same. Wood offers some energy benefits, too. It 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. A wood shake roof, however,  demands proper maintenance and repair, or it will not last as long as other  products. Mold, rot and insects can become a problem. The life-cycle cost of a  shake roof may be high, and old shakes can’t be recycled. Most wood shakes are  unrated by fire safety codes. Many use wipe or spray-on fire retardants, which  offer less protection and are only effective for a few years. Some  pressure-treated shakes are impregnated with fire retardant and meet national  fire safety standards. Installing wood shakes is more complicated than roofing  with composite shingles, and the quality of the finished roof depends on the  experience of the contractor, as well as the caliber of the shakes used. The  best shakes come from the heartwood of large, old cedar trees, which are  difficult to find. Some contractors maintain that shakes made from the outer  wood of smaller cedars, the usual source today, are less uniform, more subject  to twisting and warping, and don’t last as long.
Concrete and  Tile

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
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 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 pre-fabrication  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 hazard 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 is in need of 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 Roofroofcon

The age of your roof is usually the major factor in  determining when to replace it. Most roofs last many years, if properly  installed, and often can be repaired rather than replaced. An isolated leak  usually can be repaired. The average life expectancy of a typical residential  roof is 15 to 20 years. Water damage to a home’s interior or overhangs is  commonly caused by leaks from a single weathered portion of the roof, poorly  installed flashing, or from around chimneys and skylights. These problems do not  necessarily mean you need a new roof.
Fire-Resistant Materials
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.
Hiring a Licensed Contractor
One of the best ways to select a roofing contractor is to  ask friends and relatives for recommendations. You may also contact a  professional roofers association for referrals. Professional associations have  stringent guidelines for their members to follow. The roofers association in  your area will provide you with a list of available contractors. Follow these  guidelines when selecting a contractor:roofers
  • get three references and review their past work;
  • get at least three bids;
  • get a written contract, and don’t sign anything until you  completely understand the terms;
  • pay 10% down or $1,000 whichever is less;
  • don’t let payments get ahead of the work;
  • don’t pay cash;
  • don’t make final payment until you’re satisfied with the job;  and
  • don’t rush into repairs or be pressured into making an  immediate decision.
You’ve Chosen the Contractor… What About the  Contract?
Make sure everything is in writing. The contract is one of  the best ways to prevent problems before you begin. The contract protects you  and the contractor by including everything you have both agreed upon. Get all  promises in writing and spell out exactly what the contractor will and will not  do.
…and Permits?
Your contract should call for all work to be performed in  accordance with all applicable building codes. The building codes set minimum  safety standards for construction. Generally, a building permit is required  whenever structural work is involved. The contractor should obtain all necessary  building permits. If this is not specified in the contract, you may be held  legally responsible for failure to obtain the required permits. The building  department will inspect your roof when the project has reached a certain stage,  and again when the roof is completed.
and Insurance?
Make sure the contractor carries workers’ compensation  insurance and general liability insurance in case of accidents on the job. Ask  to have copies of these policies for your job file. You should protect yourself  from mechanics’ liens against your home in the event the contractor does not pay  subcontractors or material suppliers. You may be able to protect yourself by  having a “release of lien” clause in your contract. A release of lien clause  requires the contractor, subcontractors and suppliers to furnish a “certificate  of waiver of lien.” If you are financing your project, the bank or lending  institution may require that the contractor, subcontractors and suppliers verify  that they have been paid before releasing funds for subsequent phases of the  project.
Keep these points in mind if you plan to have your  existing roofing materials replaced:
  • Tile, metal, and slate are more expensive roofing materials,  but if you need to replace your roofing anyway, it may be worthwhile to pay a  little more for the added protection these materials provide.
  • Slate and tile can be much heavier than asphalt shingles or  wood shingles. If you are considering switching to one of these heavier  coverings, your roofing contractor should determine whether the framing of your  roof is strong enough to support them.
  • If you live in an area where snow loads are a problem,  consider switching to a modern standing-seam metal roof, which will usually shed  snow efficiently.