Blog Information

• Posted By : Rhyz Cruz
• Posted On : May 27, 2025
• Views : 8
• Category : General
• Description : In a typhoon and heavy-rain-prone country, the resilience of GI sheets in the Philippines to extreme weather conditions is priceless. This article will help you through the installation process of GI sheets for roofing to keep your building safe and secure.
• Location : Philippines

Overview

• Galvanized Iron (GI) sheets have been a staple in the Philippine construction industry for decades, especially for roofing. Their longevity, affordability, and ease of installation make them a popular choice for residential and commercial construction. In a typhoon and heavy-rain-prone country, the resilience of GI sheets in the Philippines to extreme weather conditions is priceless. This article will help you through the installation process of GI sheets for roofing to keep your building safe and secure.

  Importance of GI Sheets

  GI sheets are manufactured by applying a zinc coating on steel, offering great corrosion protection. This characteristic is important in the Philippines due to high humidity and regular rainfalls, which tend to disintegrate weaker materials rapidly. GI sheets are also light, thus lowering the overall structural load, and affordable in terms of material and installation prices. These sheets come in different profiles and colors for customization.

  Recent Standards and Regulations

  More stringent requirements for GI sheets for roofing have been adopted by the Department of Trade and Industry (DTI) in the last few years. Department Administrative Order (DAO) 20-10, promulgated in December 2020, requires hot-dip metallic-coated and pre-painted galvanized coils and sheets to comply with quality standards before they can be sold in the market. These requirements include a minimum thickness of 0.4 mm of the coated steel so that consumers can enjoy high-quality materials that can resist weather conditions.

  Preparing for Installation

  Understanding Local Regulations and Standards

  The DTI's DAO 20-10 sets minimum product standards for galvanized steel coils and sheets. This regulation ensures that all GI sheets used for roofing meet quality and safety standards, providing consumers with reliable products. When purchasing GI sheets, look for the Philippine Standard (PS) Quality Certification License to ensure compliance with these standards.

  Choosing the Right Materials

  GI Sheets

  Calculate the required number of GI sheets for your roofing project, factoring in overlaps and necessary cuts. It's recommended to have a surplus of sheets to accommodate these.

  Wooden Purlins

  These structural components serve as the support for these sheets.

  Zinc Screws with Rubber Washers

  Secure these sheets properly to create a watertight seal.

  Roof Sealant

  Seal overlaps and screw points with sealant.

  Ridge Capping

  To seal the roof’s peak.

  Essential Tools and Equipment

  Circular Saw

  For cutting GI sheets to size.

  Drill

  For drilling screw holes.

  Safety Gear 

  Helmets, gloves, and safety harnesses for working at heights.

  Measuring Tape

  For accurate measurements.

  Installation Techniques

  Preparing the Roof Structure

  Structural Assessment

  Before starting the installation, confirm that your roof structure is strong enough to hold these sheets, despite their light weight.

  Remove Old Roofing

  Before installing new these roofing sheets, remove the old material and inspect the underlying structure for damage requiring repair.

  Install Purlins

  Secure leveled wooden purlins to the roof framework with 1 to 2 meter spacing, adjusting for design and load.

  Installing GI Sheets

  Measure and Cut

  Measure the roof length with desired overhang. Use a circular saw to cut them to the required size.

  Start at the Bottom

  Start the installation of these roofing sheets at the roof's lower edge, ensuring a slight overhang at the eaves.

  Overlap and Screw 

  Overlap GI roofing sheets by a few inches and secure them to purlins with zinc screws and rubber washers. Ensure that you do not over-tighten the screws, as this can damage the sheets.

  Sealant Application 

  Apply roof sealant at overlaps and screw points for a watertight seal.

  Work Upward

  Proceed with the installation of these sheets by arranging them in successive rows, moving upwards. Ensure a slight overlap between each row.

  Ridge Capping

  Finish the roof with ridge capping at the peak for sealing and extra protection.

  Additional Roofing Accessories

  Gutters and Downspouts

  To prevent water damage to the foundation, install these.

  Flashing

  Apply flashing to the edges of the roof and around chimneys or vents to prevent water seepage.

  Valley Gutters

  If your roof has valleys, install valley gutters to manage water flow effectively.

  Safety and Maintenance Considerations

  Use Safety Gear

  Always wear helmets, gloves, and safety harnesses when working at heights.

  Stable Surface

  For safety, make sure the working area is firm and steady.

  Cautious on Slopes

  Be cautious when working on sloped roofs to prevent falls.

  Post-Installation Maintenance

  Regular Inspections 

  Check screws and sealant routinely.

  Prompt Repairs

  Replace any damaged sheets promptly to prevent water leakage.

  Cleaning

  Clean the roof regularly to remove debris and maintain its appearance.

  Key Takeaway

  Installing GI sheets in the Philippines for roofing is a manageable task when done correctly. By following the steps outlined above and adhering to local regulations, you can ensure a durable and weather-resistant roof that protects your structure from the elements. The cost-effectiveness and minimal maintenance requirements of GI sheets make them an excellent choice for both DIY enthusiasts and professional contractors. As the Philippine construction industry continues to evolve, GI sheets remain a reliable option for building safe and resilient homes and buildings.