Roof
A view of typical vintage house with tile roof

Roofing and Guidelines

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Roofs have many expectations that come from us, including the prevention of water intrusion and protecting its building beneath it. Moreover, the roof is required to resist high winds, high and low temperatures, exposure to radiation, and snow as well as ice formation. Roofing systems tend to fail when the wind produces forces that are greater than the roof’s strength. Some winds can tear roof coverings from its decking and can even tear roof decks from its framing.

If winds are strong enough to allow debris to puncture a roofing system, then serious additional damage could potentially occur, especially if it’s a flat roof. Because the roofing system is punctured, rain water can now possibly enter the building. After water enters, excess moisture becomes trapped and mold quickly starts to grow. Roof repairs can potentially cause even more problems, and that’s why there are proper guidelines and building codes that contractors are forced to follow and maintain.

In order for a roof to be considered in good performance, there must be a proper selection of a roof system for that particular environment. Consequently, some factors must be taken into consideration when exploring new roof options and new roof contractors. Thr roof covering, deck, ends, underpayment, and flashing must all be taken into consideration, and choosing the correct style of these materials that works best with the weather environment in the roof’s location is also extremely important. Additionally, it should be recognized that proper roof installation is achieved through experience, construction techniques, inspections, and compliance with code requirements. These requirements for roof coverings are different for all covering styles and types, and they’re different for the slopes of every roof.

General roof covering requirements include fire resistence, insulation, load and pressure requirements, weather protection, materials, etc. Most roofing systems require two layers of underpayment. Additionally, underlayment in areas that contain high winds must be secured with corrosion-resistant fasteners, and these fasteners must be placed within 36 inches of each other. Furthermore, all roofs are required to be installed on continuous sheathing. Some roof converting systems can have spaced sheathing, but it’s rare and it’s based on the slope of the roof.

Guidelines for Proper Roof Installation

  • All roof coverings down to the roof decking must be removed (even underlayment)
  • Decking must be removed where it’s deteriorating or water damaged
  • All underlayment must be labeled with the appropriate ASTM (American Society for Testing Materials) numbers
  • Metal drip edge is required at the eaves of all roofs
  • Fasteners should be flush with the roofing materials and not overdriven or underdriven
  • Corrosion Resistant Fasteners are required for all roofs
  • The maximum weather exposure of the roof should not be exceeded
  • All rusted or damaged roof flashing must be replaced
  • All damaged vent flashing, metal edging, drain outlets, collars, and metal counter flashing needs to be replaced
  • Any siding or exterior wall cover must be kept up off of the surface of the roof by at least 12 inches
  • Proper ventilation is required for all roof installations for both the construction of new roofs and the replacement of existing ones

Roofing Guidelines for Asphalt Shingles

  • The maximum number of layers of roofing is 1
  • New docking overlay is required
  • The minimum slope for standard single underlayment installation is 4:12
  • Primary Step Flashing must be properly laced
  • At least 6 fasteners is required for each shingle

Roofing Guidelines for Cedar Shingles

  • Solid decking is required
  • Minimum slope for cedar shingles is 3:12
  • Primary Step Flashing is required to be properly laced with each shingle
  • Metal drip edge is required

Roofing Guideline for Flat Roofing Systems

  • The removal of all existing roof coverings is required
  • Roof should have a minimum of 1/4-inch slope
  • Secondary overflow drains are required 2 inches above the primary drains

Overall, roofing systems are difficult to install and maintain. But in order to properly protect the building underneath of it, the roof needs to be in good condition. This requires that the roofing contractors follow strict guidelines when installing new roofs and replacing existing ones. If all of these guidelines are followed and maintained, then the expectations of the roof will be met and the building beneath will be protected.

Sources:
http://www.roofkey.com/roofkey-roofing-guidelines.html
https://www.fema.gov/media-library-data/20130726-1706-25045-9347/chapter8.pdf

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