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The roof of a structure is susceptible to several defects during its course of life, but the identification of such issues is not an easy task for the contractors. Understanding the common defects in roofs and their possible location can help in easy detection and fixing of the problems.

Weathering, wind, improper design and maintenance are some of the common causes of deterioration of roofs. Several other defects occur mostly due to a result of these primary causes.

This article lists out ten major defects observed in roofs and the measures to prevent them.

1. Weathering Defects in Roofs

The roof material used can be either organic or inorganic in nature. Organic roofs get easily deteriorated due to weathering action in comparison to inorganic roofs. The rate of deterioration increases if the atmosphere is concentrated with pollutants or industrial effluents.

Some tips to prevent weathering of roofs are:

  1. Inspection of roofs once or twice a year
  2. Prevent trees from interfering with the roof
  3. Ventilate the roofs constructed in areas prone to more snow

2. Wind Defects in Roofs

Roofs located in windy areas are subjected to upward pressure that blows the roof edges. It rips off the membrane or the roof system.

Wind Action on Roofs
Figure-1: Wind Action on Roofs

To prevent this from happening, it is recommended to fasten and secure the roof along its perimeter and the main roof structure.

3. Roof Defects due to Improper Maintenance

Flat or low-sloped roof demands huge maintenance as it collects more sediments and water that eventually destroy the roofing material. Therefore, it is necessary to conduct routine cleaning and maintenance checks for buildings with flat or sloped roofs.

Roof Problems due to Lack of Maintenance
Figure-2: Roof Problems due to Lack of Maintenance

4. Roof Defects due to Improper Design

Roof defects caused due to improper design are comparatively difficult to fix. Such defects can be corrected by replacing the roofing materials. Some of the common mistakes performed in roof design are:

  1. Improper roof slope, drainage, and sagging roof, resulting in water accumulation and deterioration of the roofing material.
  2. There is no proper design system to allow expansion and contraction of the deck material.
  3. The structure supporting the roof system is weak and deflects due to active loads.
  4. The use of incompatible roof materials.
Improper Design of Roof
Figure-3: Improper Design of Roof

5. Roof Defects due to Base Flashing

Base flashing is performed at the joint between the surface of the roof and a vertical surface to guard against water penetration. Some common base flashing issues that cause defects in roofs are:

  1. Insufficient height of base flashing
  2. Poor adhesion of base flashing
  3. Insufficient coating
  4. Loose insulation below
  5. Incorrect fastening to the surface
Flashing Types in Roofs
Figure-4: Flashing Types in Roofs

Always install base flashing as per standard requirements and specifications. The base flashing installed must be properly adhered to the roof surface to prevent leakage.

6. Roof Defects due to Flashing Material and Procedure

The purpose of the flashing of roofs is to seal the sections and other parts of the building. Incorrect flashing procedure results in the penetration of water between the roof systems and the roof structure. Early flashing defects must be sealed to prevent future defects.

7. Roof Defects due to Drain Flashing

A good drain system requires a sufficient amount of drain openings. The drain flashing process is not as easy as constructing drain openings. Always provide an overflow scupper to prevent the accumulation of water during an emergency. The collection of water around the openings can cause moisture damage to the roofs.

Roof Drains and Scuppers
Figure-5. Roof Drains and Scuppers

8. Roof Defects due to Penetration Flashings

Some of the issues with penetration flashing that cause roof defects are:

  1. Improper finishing of the metal surfaces
  2. A deteriorated counter
  3. Improper design work
  4. Damage to roofs due to standing water behind the penetration curbs.
Penetration Flashing
Figure-6: Penetration Flashing

Penetration flashing must be properly held to the roof to prevent any leakage and clogging of water.

9. Roof Defects due to Metal Base Flashings

This defect is commonly observed in the bituminous roof system. The metal flashing material and bitumen have high contraction and expansion rate that creates cracks and openings. This leads to further water penetration and damages to the roof surface. It is hence recommended to use a bituminous flashing for a bituminous roofing system.

10. Roof Defects due to Rooftop Equipment

Rooftop equipment like solar panels, satellite antenna, A/C compressor, etc should not be directly placed over the roof surface. A support structure can be constructed over the roof membrane to carry the equipment.

Roof Defects due to Roof Top Equipment
Figure-7: Roof Defects due to Roof Top Equipment

FAQs

What are the causes of roof problems?

Roof problems are mainly caused due to:
1. Weathering defects of roofs
2. Damage of roof due to wind action
3. Roof damage due to rooftop equipment
4. Roof defects due to improper flashing
5. Roof defects due to improper design
6. Improper maintenance of roof

How does improper flashing affect the roof system?

Flashing is performed for sealing the openings in the roof to prevent water penetration or water clogging. Base flashing, drain flashing, and penetration flashing for roofs are performed efficiently to avoid any leakage of moisture or water. The flashing material must be compatible with the roofing material. The use of incorrect flashing procedure or material results in the penetration of water between the roof systems and the roof structure.

What are the issues with incorrect roof design?

Roof defects caused due to improper design are comparatively difficult to fix. Such defects can be corrected by replacing the roofing materials. Some of the common mistakes performed in roof design are:
1. Improper roof slope, improper drainage, and sagging roof, resulting in water accumulation and deterioration of the roofing material.
2. No proper design system to allow expansion and contraction of the deck material.
3. The structure supporting the roof system is weak and deflects due to active loads.
4. The use of incompatible roof materials.

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