Phone Number: 719-315-4669
ROOF TRUSS MEMBER NAMES
The Truss Mill, Canon City Colorado
A roof truss is a premanufactured part that is used to cover a structure to provide support of the roof and slope to shed water. A roof truss can be made from wood or metal but we will only be talking about wood roof trusses here. A roof truss is very similar to a bridge and basically is a bridge to cover a home or structure.
The different members that make up a truss are helpful to know only from the standpoint that when you are trying to speak about the parts of a truss it is easier to talk the same language when you have something to refer to from a simple starting point.
I've been in the truss industry for many decades, and I've heard every part of a truss called something different in every part of the country and in different countries. There's nothing wrong with calling any part of a truss anything you want to but it's like speaking different languages. It's important to know that the terminology used here is what is used in the field in general in Colorado. These are not the technical terms. Engineers would call trusses components and may not use the same names as are used here.
The images below are to help as a simple reference for those who may be trying to understand a truss for the first time. You may be from a different part of the country or a different country and you are just trying to understand what to call the different parts of a truss.
ROOF TRUSS MEMBER NAMES
Members highlighted in Bright Green
TOP CHORD
These members create the upper profile of the truss. When you are standing outside of your home you see this as the roof. Plywood and shingles are attached to these members. This is what you walk on when you put your Christmas lights up. 2x4 lumber normally.
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Dimensions in trusses are typically shown like "25-0-0". These dimensions look a little different than usual.
If a dimension is shown as "8-9-9" as it is for the overall height of this truss it means that it is 8 feet 9 inches and 9/16th's of an inch. The last digit at the far right is 16's of an inch.
OVERHANG
These members are extensions of the top chords that extend out from the walls of the house. They are sometimes called an eave. This is the part of a house that you walk under when you are trying to get out of the rain.
BOTTOM CHORD
This member makes up the bottom profile of the truss which creates the ceiling in a house. 2x4 lumber normally.
WEBS
Webs are members of a truss that support the top and bottom chord members. They are used to hold the truss together and give it strength. They can be seen when you are up in the attic of your house. 2x4 lumber normally.
PEAK
The peak of a truss is just a simple part of the truss where the left and right top chord members come together and are supported by webs. This is normally the tallest part of a truss which can sometimes be referred to as the ridgeline. It is a landmark on a truss that is used to make the profile but isn't actually its own member but part of several members coming together at one location.
HEEL
The heel of a truss is typically the height of the truss at the outer wall. It is a term used to refer to the location of the start of the bottom chord of a truss or the start of the span of a truss that usually comes together with the top chord. The heel is similar to the peak of a truss in the respect that it is a landmark of a truss, but it isn't actually a member. It is a location on a truss.
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In the image shown this heel is 6 and 10/16 th's inches tall.
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There are many different types of heels but the one shown is the most common.
SPAN
The span of a truss is normally only the length of the bottom chord of a truss. The span in the above picture is 25 feet. This is shown as "25-0-0". The span is an important dimension because it is usually the same out to out dimension as the walls of the house. The terms "usually" is used because it can be different for different types of looks like in the case of a cantilever which extends beyond the walls of a house.
TRUSS HEIGHT
The height of a truss, shown in the above picture as "7-7-13" at the left side, is referred to as the height of the truss. This is the dimension from the bottom of the bottom chord to the top of the highest point of the truss which is normally the peak. The overhang is not included in this dimension because it is important to know how tall the house will be when the truss sits on top of the walls and this dimension will help with knowing that value.
OVERALL HEIGHT
The overall height of a truss, shown in the above image as "8-9-9", is the dimension of a truss from the bottom of the lowest point on a truss, typically the bottom of the overhang, to the highest point on a truss, typically the peak. This dimension is mostly important for the construction phase of a house. It is important to know for shipping the trusses because if a truss gets too tall it may be too wide to ship to the building location. It may also be too wide for the truss manufacturer to build in their shop. In these cases, a truss manufacturer would make the truss in two parts that would be put together at the jobsite. These are called "Piggy-back" trusses.
SLOPE OR PITCH
The slope of a truss is the angled part of a roof that is made up of the top chord of a truss. This is the part of a roof that has an angle to it that has shingles typically on it. When it rains the water runs down the slope to the gutter. The slope is also referred to as the "Pitch".
The slope is measured in an increment that is usually referred to as something like a "7/12" as one example. A "7/12" means that for every 12 inches of horizontal distance the member rises 7 inches. It can also be measured in feet if the distance allows. That would be measured as for every 12 feet of run the roof rises 7 feet.
JOINTS
A joint of a truss is any member of a truss that comes together and is held together with a metal truss plate. These are webs or chords generally that meet. They are held together with a metal pressed plate sometimes called a gusset that is pressed together with a high-pressure hydraulic press or roller.
PLATE
A plate is a flat piece of metal that is typically 20 gauge in thickness and has holes stamped into it that create what are called "teeth". The teeth are just the portion of the metal that is stamped out of the flat part of the plate but is still connected to the plate for a significant amount to add enough strength to the teeth so that the plate can be smashed into the wood truss and held in place with an incredible amount of force.
Truss plate being pressed into a truss.
