Measuring
Measuring for metal roofs require a bit more attention but are essentially the same process for a shingle roof. After you review this section you will measure an example roof! We will break it down step by step in this section.
Eves
After you have drawn your diagram start by measuring the eves of the property. You can remember an eve as anywhere that water will shed or that a gutter would go. Follow the perimeter of the home measuring your roof eves. The eve measurements will later be used to order Gutter Apron, Drip edge or Fascia wrap depending on the project specifics.
*Most materials will come in 10’ sections.
Rakes
The Rake is the vertical slope extending to a Ridge. This is the roofline along the Gable. Rake metal will be applied here to create a watertight seal where the roof line ends and to complete the overall look of a new metal roof.
*Make sure to allow extra length for your fold at the bottom
*Most materials will come in 10’ sections.
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Hips
The term “Hip” refers to the entire roof plane. You can see in the image to the right that just the hip caps are red. When you measure for hip cap make sure you pull your tape from the bottom side of the slope to account for the overhang that shingles will allow.
*Hip cap should always have a few more inches added to the true measurement to allow for the fold at the bottom of the slope.
*Hip cap should lap 4”-6” (allow this in measurements)
*Most materials will come in 10’ sections.
Ridge
Ridges are traditionally covered with two products. One is a standard ridge cap. That cap is used on slopes that other forms of ventilation are present. A ridge vent is the second type and is commonly installed on the most upper ridge to allow proper heat extraction from the attic. There must allows be a way for the roof to ventilate. Without airflow the panels will hold heat and cause damage to the material, high electrical cost and the color to fade.
*Most materials come in 10’ sections.
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Valley
Valleys can be a problem area for homeowners that have an existing metal roof and are experiencing leeks. If the material is cut short and is moved closer to the mottos edge of the valley to make up the difference “blow back” can happen. Blow back is when wind driven rain is forced upward toward the peak of the roof and ends up going under the panel far enough to reach the top of the valley flashing. This is not an issue when the valley metal is ran high enough to be lapped properly while allowing the right amount of length at the bottom for water shed.
*Most materials will come in 10’ sections.
Panels
When measuring for your roof panels you have to measure a few more times than you would would for a standard shingle system. You will see on this diagram that you have multiple measurements of the same slope in some instances. No matter how square a home looks you always want to measure each area just to be sure. This is especially important over long distances like the back slope of this home. Even if the house is off by an inch you will be able to tell by the time you get to the other end of the run. When you are measuring to a ridge remember to allow for 1” overhang on the bottom. If the home has shingles with the correct overhang then your measurement should be true. Never measure to the exact center of the ridge. Allow appropriate space for ventilation. A minimum of 3” (1 1/2” per side)
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End-Wall
End-Wall flashing is used to create a water tight edge against the wall of the structure down onto the roofing panels. The fundamental difference between End-Wall Flashing and Side-Wall Flashing is that End-Wall goes against the water flow. As you can see here this home extension is connected and sealed with End-Wall Flashing
*Most materials will come in 10’ sections.
Side-Wall
Side-Wall flashing is used when a sloped roofline meters a wall. Here you can see that another gabled portion of the home is connected with Side-Wall Flashing. However unlike End-Wall flashing this flashing will go with the flow of the water.
*Most materials come in 10’ sections
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Chimneys
Chimneys can be tricky for someone who isn’t prepared for it so make sure that you measure for the chimney. You will need all four sides measurements and also note if the chimney has a “cricket”. In most states a cricket is required for proper water diversion behind the chimney.
Skylights
Skylights are something else you will need to make a note of when you measure the roof. Skylight flashing kits can be ordered for most standard size skylights. Measure the skylights on all four sides and make a note of the type. You will generally have a flat or bubble.
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Boots
Boots for metal roofs are very similar to a pipe boot on shingles except for the lead base that allows it to form to the rib and be fastened directly to the roof. You will see these in two most popular forms. The first is a common “Slip over” type boot. This will generally be used for exhaust pipes ranging up to 6 inches however they come up to 9 inches. Secondly you will see a boot on the diagram that is blue. This is a “zip” boot or also commonly referred to as a “split” boot. These are used primarily on power mast when sliding over the top of the penetration is not an option.
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Transitions
Transition metal is used when a roof elevation changes pitch. Typically this is when a roof line extends out over a porch but can be seen in other forms. When one roof line meets another on the same plane you will have a transition or valley. In this diagram you can see the difference.
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