Replacing a residential roof requires careful planning and calculation of materials, costs, and labor requirements. The process of estimating materials and dimensions for a roof replacement is called a roof takeoff. A precise takeoff helps ensure that a contractor orders the correct amount and lengths of metal panel, trim, and accessories to manage project costs effectively.
In the previous article in this series we discussed the measuring processes for roof estimation. Today, we dive into how to calculate the amount and types of material that you will need for your quote.
Types of Materials for Metal Roofing
The next step is to determine the types and quantities of materials needed. The three main material categories are roofing material, underlayment, and additional components. In this article, we will review roofing material and underlayment for the roof sections. In the next article, we will dig into trim parts and other components.
A. Roofing Material
Measure the roof per the above directions. Metal roofing runs vertically on the roof, that means from top to bottom. For determining the number of panels needed, you can estimate each section of roof by dividing the width of the section by the coverage width of the panel you have selected. For example: our Panel-Loc Plus panel has a coverage width of 36-in (3-ft), so a roof section measuring 36-ft wide would require 12 pieces of panel. The length of the panels is determined by the length measurements taken during your manual measurement process (top to bottom), noting that some sections of roof may have obstructions and oddities causing different lengths of panel needed across the whole section. Some contractors order all the lengths at the longest length and make all their cuts on site, while others send very specific cut lengths to the manufacturer to pre-cut before shipping. Please note: most manufacturers will not cut the angled pieces, so you would need to provide the length to the longest point of an angle.
Be sure to ask your manufacturer if they offer standard lengths or cut-to-length panels and know the maximum lengths that they provide. Regardless of the option available, if your roof section needs a longer panel, you will be required to overlap another panel to cover the distance. Be sure to consult the manufacturers guide on overlapping panel, as in most cases it will require a 6” overlap in the panels; so, if you order exact to the measurements, you will end up short.
Example chart for panel lengths:
Typically, it’s wise to order your roof panels with some overhang while considering the gutter / eave finish that the customer may desire. Some panels can extend 1-in – 6-in beyond the end of the roof for water runoff. Consult your installation manual for recommendations.
Order Extra Material: To account for errors when cutting around obstructions or oddities in the roof (including valley cuts, dormers, etc.), most customers will order an extra piece of full-length panel for sections of roof that have said obstructions. As you hone your skills with metal roofing and install procedures, you may cut back on your waste and cost factors by ordering fewer extra pieces.
B. Underlayment
Underlayment is the protective layer between the roofing material and the roof deck, typically available in rolls. Measure the total roof area and purchase underlayment accordingly. You may need additional rolls to account for overlapping or areas requiring extra layers. Be sure to consult the installation manual for recommendations on underlayment. In some areas, you may also need ice shield or other waterproofing material applied to all or part of the roof before installing panels.
Stay tuned for our review of other roofing materials you will need
As we continue to understand more about metal roofing, it’s clear that there is a lot to know. Next, we will uncover other materials that are necessary in completing the roof, like trim, sealant, and more. But, until then, if you’d like to learn more about our products and services, please review the products section or contact us to be connected with a salesperson to get started.
