There are many different types of roof trusses that are used as the framework to support the roof of a home. Most roof trusses are created out of wooden beams that are secured with metal brackets and bolts to add strength to the structure. The roof trusses can be configured into numerous different designs to add a sense of style to the roof and improve the look of the home.
Common Types Of Roof Trusses
The most common types of roof trusses are triangular in shape, using beams to support the interior of the triangle as well. These roof trusses are the ones typically used for homes because of the ease of completing the design. The size and dimensions of the triangular shape do not matter, as they all are considered the common design and are built the same way.
Another often used roof truss configuration is the mono configuration. The mono configuration is used when there is a slope on one side of the roof. This type of roof truss configuration is typically used with other configurations to create a custom or uniquely style roof.
A flat roof truss configuration is also used often in the construction of a roof for the home. These types of roof trusses look exactly like the name describes, a long rectangular truss configuration that has a short height. The flat configuration is often used with the mono configuration to create different roof styles.
Roof Truss Terminology
In order to help you understand what is being discussed, first we will go over some of the common elements of roof trusses and discover the terminology used by the professionals. First we want to imagine a common roof truss. Think of it as a three sided triangle pointing upwards. The top two lengths that determine the roof’s pitch are known as the upper chords.
Then the bottom of the triangle is know as the lower or bottom chord.
Next we have the supporting pieces inside the triangle. These are known as web members. Web members can also be named by horizontal and vertical positioning. Vertical web members are called vertical posts and diagonal ones are called simply diagonals.
Some roof trusses have a center support that goes from where the upper chords meet to the lower chord. This is know as the king post. The final part that we want to mention is the piece that commonly hold sections together. This is commonly known as a gusset plate. To make it clear, here is a definition list of the terms:
• Upper Chords: The top two lengths of the roof truss that form the roof’s pitch.
• Lower Chord: The bottom length of the truss that often forms the bottom of a triangle.
• Web members: The cross members inside of the main truss structure. These are the smaller supporting members that typically form a “W” or an “M” shape in simple truss designs.
• Vertical Posts: Web members that run vertically.
• Diagonals: Diagonal web members.
• King Post: The center vertical post that connects the upper chords to the lower chord on a lot of roof truss types.
Type of Roof Truss to Use
The type of roof truss to use for your home is going to depend on a few different factors. You want to take into consideration how much weight will be supported from both the roof itself and from wind and snow conditions.
One of the main factors in making your truss choice is going to be the length of the span that you will need to cross with the truss. Here we are going to name some commonly used housing roof trusses and tell about what length of span they should be used to cover:
• Up to 16 feet: King Post truss- a simple truss that consists of two upper chords, a lower chord and a single king post in the center.
• 10 – 22 feet: Queen Post truss- Upper and lower chords with a king post and 2 additional web members.
• 16 – 33 1feet: Fink truss- Upper and lower chords with “w” shaped web members.
• 24 – 36 feet: Howe truss- Upper and lower chords with a king post, 2 vertical posts and 2 diagonals.
• 30 – 36 feet: Fan truss- Upper and lower chords with 2 vertical posts and 4 diagonals.
• 32 – 44 feet: Modified Queen truss- Upper and lower chords with a king post and 4 additional web members.
• 40 – 60 feet: Double Fink truss or Double Howe truss- Upper and lower chords with 7 and 8 web members respectively.
• 44 – 60 feet: Modified Fan truss- Has upper and lower chords with 9 web members.
• 50 – 80 feet: Double Inverted truss- Similar to using 2 Howe trusses.
• 54 – 80 feet: Triple Fink truss or Triple Howe truss- Both have upper and lower chords and 12 web members.
Take note that whenever it says “Upper and lower chords” above, we are referring to the two upper and one lower chord that typically form a triangle. Then notice that typically the number of web members increase as the length of the span increases. So this should give you a good idea of where to start when looking for trusses for your home.
Keep in mind that there are countless other trusses available for almost any shape of roof you desire. These are just the most common ones. There are for example trusses for flat roofs, cone roofs and roofs off all shapes and sizes. Be sure to check with a professional to be sure you make the best truss selection for your situation.
Different Styles Of Roofs
These three common types of roof trusses can be used to create numerous different styles of roofs for the home. Some individuals like to choose the more traditional roofing styles while others prefer the fanciful creations that using some or all of these types of roof trusses allows.
One of the most common roofing styles created from modifying the basic types of roof trusses is the scissors style of roof. In this style, the base of the common roof truss is raised in the middle to a point in the center of the triangle. This style of roof creates the cathedral ceilings that many people find attractive.
Another common configuration for the roof is the room-in-attic style of roofing. In this configuration, three triangular trusses are set around a large square open area and supported with long beams. This style of roof is used to create attics intended for storage as well as attic bedrooms.
Exotic Roofing Styles
One of the most creative styles of roof that can be created out of roof trusses is the Polynesian (or Duo-Pitch) style of roofing. This type of roofing resembles a crown, with a single high point and two smaller triangles attached to the side. The Polynesian style can be used as a single peak on a home or replicated several times around the roof of the home to create a beautiful and unique design.
Another creative roofing style is the Gambrel roofing style. This style is what gives the front of barns their distinctive look, but many homeowners are deciding to use this style for their homes as well. Using the Gambrel style of roofing for your home gives the home a dramatic appearance and can allow more sunlight into the rooms directly under the roof as this style provides more flat areas for windows and skylights.
Photos by daisybush and Bryn Pinzgauer, Creative Commons Attribution License