How to Measure for a Metal Roof: Easy Step-by-Step Guide

Last updated on May 12, 2024

Learn the steps to accurately measure your roof for a metal installation, ensuring you purchase the right amount of materials for your project.

metal roofing tools

Key takeaways:

  • Sketch an accurate aerial view of your roof
  • Take precise measurements of length, width, slopes, and features
  • Calculate the area of each roof section using appropriate formulas
  • Check local building codes and permit requirements
  • Consider the type of metal roofing panels and their installation styles

Draw An Aerial View Of Your Roof

draw an aerial view of your roof

Begin by sketching an accurate representation of the roof’s shape and layout. This drawing doesn’t have to be an architectural masterpiece, but it should include all ridges, hips, valleys, dormers, and eaves. For complex roofs, consider creating separate sketches for different sections. Label each part clearly, as this will serve as a reference when transferring measurements. Ensure to note any features like skylights or vents that could affect the installation process. If available, use satellite images or drone photography to ensure precision. Remember, a well-drawn diagram will simplify the subsequent steps and help avoid material overage or shortage.

Take All The Necessary Measurements

Begin by measuring the length of your roof from the eaves to the ridge. For accuracy, measure each plane of the roof separately. Next, determine the width by measuring along the eaves, where the roof meets the gutter. If your roof has overlapping sections, measure them individually to ensure precise calculations for materials.

When dealing with slopes, use a ladder safely placed against the house for accessibility. Measure the slope, known as the ‘pitch’, using a level and a tape measure – for every 12 inches on the level, the vertical rise indicates the pitch. Record these figures, as they’re critical for estimating materials and ensuring proper water drainage.

Don’t forget to include the length of the rakes or overhangs beyond the walls in your measurements. Every extra inch requires additional roofing material. For valleys and hips, measure their entire run. Valleys will need additional materials for underlayment, while hips will affect how panels interlock or are cut.

Note the positions of vents, chimneys, skylights, or any other roofing features. These areas require flashing and may affect the fitting of metal panels. Measure their height, width, and base, which matters for flashing and sealants, ensuring a watertight roof installation.

Record all measurements clearly, double-checking each one. A thorough and meticulous approach here will save both time and expense during the roofing process.

Calculate The Area Of Each Section

To accurately compute the area for each roof section, follow these steps:

1. Rectangular and Square Areas: Multiply the length by the width for every rectangular or square section. Use the formula: Area = Length x Width.

2. Triangular Areas: For triangles, measure the length of the base and the height, which is the distance from the base to the peak. Apply the formula: Area = 0.5 x Base x Height.

3. Trapezoidal Areas: If a section resembles a trapezoid, with two parallel sides of different lengths, measure both bases and the height. Use: Area = Height x (Base1 + Base2) / 2.

4. Irregular Shapes: For any irregular or complex shapes, divide them into basic geometric shapes whenever possible and apply the appropriate formulas.

5. Overall Total: Add the area of all individual sections to get the total square footage of the roof.

6. Extra Material: Always factor in a waste allowance, which can range from 5% to 20%, depending on the complexity of the roof and the type of metal roofing material. This accounts for overhang, trim, and errors.

Refer to your diagram while performing calculations and make sure to record your measurements accurately to ensure you order the right amount of material.

Check for Local Building Codes

Before proceeding with the installation process, it’s crucial to familiarize yourself with relevant local building codes that can influence the quantity and type of materials required, as well as the installation methods.

These codes often dictate specifications like minimum roof pitch, fastener types, and underlayment barriers to ensure safety and durability.

Additionally, some regions may require permits or inspections for metal roofing projects.

Compliance with these regulations not only ensures the integrity of your roof but also avoids potential legal issues and fines.

It’s advisable to contact your local building department or consult a professional roofer to clarify these requirements.

Consider the Type of Metal Roofing Panels

Different metal roofing materials come in various sizes and installation styles. Standing seam panels, for instance, are often designed with interlocking edges and can span longer lengths without seams. On the other hand, metal tiles or shingles come in smaller units, appearing like their traditional counterparts but requiring more pieces to cover the same area.

Factor in the panel’s width and length when calculating your roof’s material needs. The width of panels typically ranges from 12 to 24 inches, necessitating precise measurements to ensure panels fit perfectly with minimal waste. The length of each panel should be measured to run from the ridge to the eaves, with an allowance for overhang as per design requirements or personal preference.

Take into account the orientation of your roof’s slopes. Some patterns and types of metal roofing are better suited for certain layouts and may affect the number of panels needed. For instance, large, wide panels may not be ideal for complex roofs with multiple hips or valleys.

Lastly, consider the potential for thermal movement – metal expands and contracts with temperature changes. Different systems, such as those with concealed fasteners, allow for this movement without the risk of leaks or damage, impacting your measurement approach to accommodate installation specifications.