Terms & Definitions

There is a lot of confusion around roofing. This is due to a number of reasons that range from the insurance process to what color of shingle should be chosen. One of the biggest hurdles for homeowners is understanding what a roof includes. There are many terms that are used in roofing that are foreign to the general public and hopefully this will help you as you move forward in the roofing process!

Common Roofing Terms 

  • Asphalt – An organic bituminous compound in the manufacturing of composition shingles 
  • ASTM (American Society for Testing of Materials) – A voluntary organization concerned with the development of standards, testing procedures, and specifications. Many city building codes use ASTM standards. 
  • Base  Flashing – The portion of the flashing which is attached to, or rests on the roof deck. 
  • Blend – The mixtures of various colored granules on the surface of the shingle. 
  • Blisters – Bubbles that may appear on the surface of an asphalt shingle roof. 
  • Caulk – A substance used to fill a joint or a void. Used to seal roof accessories. 
  • Class “A” – The highest fire resistance rating for roofing as per ASTM E-108. Shingles with this rating should withstand sever exposure to fire from sources originating outside the building. Other classed are B and C. 
  • Closed Valley – When roofing materials cover the entire valley. 
  • Coating – A layer of viscous asphalt applied to shingles in which the granules are embedded. 
  • Collars- Preformed flange placed over a vent pipe. There are two types, lead jacks and rubber boots. Also called vent sleeve. 
  • Counter Flashing – Flashing on a vertical surface to prevent the flow of water from getting behind the base flashing. The cap flashing overlaps the base flashing. This flashing is generally not changed in a reproofing job. Sometimes called Cap Flashing.
  • ​Course – A horizontal unit of roofing running the length of the roof. 
  • Cricket – A small peaked saddle constructed on the top of the basic roof and behind the chimney. A cricket is generally not required. 
  • Cupola – A structure rising above the main roof. It is usually ornamental, but may be used for ventilation. 
  • Dead Level –  A too or section of roof without any pitch. 
  • Deck – The material installed over the framing of a structure on which shingles are installed. The primary materials are Oriented Strand Board (OSB) or Plywood. 
  • Dormer – A window unit projecting through the sloping plane of the roof. 
  • Drip Edge – Usually metal strip used on the eave and rake to allow for water run off without damaging underlying materials. 
  • Drip Course – The first course of shingles that slightly overhangs the edge. 
  • Eave – The horizontal edge of a roof that projects over the outside wall. 
  • Exposure – The portion of the shingle that is exposed the the weather. Usually measured from the butt of one shingle to the butt of the next overlapping shingle.
  • Lap – The overlap of surface of one roofing material to another. 
  • Laminated Shingles – Shingles containing more than one layer of tabs creating extra thickness. Also called dimensional or architectural shingles. 
  • Low Some Application – Method of applying shingles on slopes between 2/12 and 4/12 pitches. 
  • Modified Bitumen – Roll roofing membrane with a polymer modified asphalt. The roll will generally have a fiberglass or polyester mat for reinforcement. 
  • Normal Slope Application – Method of installing shingles on a roof with a pitch between 4/12 and 21/12. 
  • Open Valley – Valley in which metal is used and roofing material does not cover the entire valley area. 
  • Saturant – Asphalt used to impregnate felt for waterproofing and strength. 
  • Seal Down – A factory applied asphalt strip used to bond a shingle to the one above. This is used to provide wind resistance. 
  • Sheathing – Exterior grade boards used as a roof deck. 
  • Side Lap – A horizontal lap. 
  • Skirt Flashing – A large often single piece of flashing commonly found at the bottom of a dormer or addition. 
  • Slope – The degree of incline of a roof plane. This is measured by the inches of rise per foot. Also called pitch. 
  • Soffit – The finished underside of an eave. 
  • Soffit Vent – An under eave opening needed for intake of outside air. These are not part of a typical roofing job, but are needed for good attic ventilation. 
  • Soil Stack – A vent pipe that penetrates the roof. 
  • Span – The horizontal measurement from eave to eave. 
  • Spire – A tower of roof tapering up to a point. 
  • Square – A unit of roof measurement covering 100 square feet. 
  • Square Butt Shingles – generally three tab 20 year shingles – not laminated. 
  • Starter Course – The first course of shingles installed on your roof. It will be under the first exposed row. Often these shingles are 20 year three tab shingles, as not to create an awkward hump, these are used even when heavier laminated shingles are installed. 
  • Step Flashing – Flashing along a roof slope against a wall or chimney using succeeding courses of flashing material placed in conjunction with layers or courses of roofing materials. Step flashing is generally in 4X4X8 inch pieces. 
  • Tab – The portion of the strip shingle defined by cut outs or slots so when installed, material appears to be individually applied. Thisis the portion of the shingle that is also exposed to the weather. Sometimes called the “butt” of the shingle. 
  • Underlayment – Often made of felt or synthetic materials that is applied under the shingles to the entirety of the roof surface to waterproof that roof. Homeowners should know that there is a wide range in price and quality. 
  • Valley – The intersection of two roof slopes. 
  • Vent – An outlet for air or ventilation. 
  • Weathering – Changes in color, texture, or efficiency brought about by exposure to outside elements. 

Common Insurance Claim Terms 

  • Actual Cash Value – Actual Cash Value or ACV is the fair market value of an item today at its current condition. 
  • ACV Policy – An ACV policy withholds the depreciation (nonrecoverable depreciation) and only pays out the ACV amount and the homeowner is not only responsible for their deductible, but also any cost above the ACV amount. 
  • Deductible – The deductible is a different amount for each homeowner/policy. This is the portion of the job cost that the homeowner is responsible for paying. 
  • Depreciation – This describes the reduction in the value of an item as a result of wear and tear, age, or obsolescence. Items continue to depreciate until the end of their useful life. Depreciation lowers the value of an item over time. 
  • Nonrecoverable Depreciation – Some insurance policies do not pay for the depreciation, this is called nonrecoverable depreciation. 
  • Recoverable Depreciation – Recoverable depreciation is that amount withheld from the first payment in a RCV policy. This amount is total of the second check if there are no supplemental items. 
  • RCV Policy – An RCV policy will pay the total cost of the replacement except for the homeowner’s deductible. They do withhold the depreciation amount until after the work is complete and there is proof that the homeowner has paid their deductible. 
  • Replacement Cost Value – Replacement Cost Value or RCV is the amount of money that to would cost to replace an item today with an item of like kind or quality, regardless of its current age or condition. 
  • Supplement – A supplement is an additional amount of money that we have to submit a request for. We request this amount based off of a Xatimate report for any missing or wrong items from the original estimate the insurance agency gives the homeowner. 
  • Xactimate – Xactimate is a pricing program that most insurance companies use to create the estimate for the losses to a property. We use this in order to submit a request for a supplement. 

Give us a call today. No matter your situation, Mill Creek Roofing is here to deliver an outstanding roof repair service in the Houston and surrounding areas so that you and your home are protected!



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