Building Example:  Garage with Hip Roof

(Garage Door, Entry Door & Window)

 

This example is to help Windloadcalc.com users understand how to enter information for a Hip Roof building. 

 This following will give you the understanding of how to properly enter your building information and get the wind load calculations needed for door(s), window(s), and your roof. 

 You will also be given the understanding of how to apply zones to your door(s), window(s), and roof.

 First, you must enter your building’s information. 

 Reference the images below.  The first image is “Building Information”.  This is a section on the program that is required. 

The second image is a diagram of the garage that we will be finding wind loads for.  The numbers applied to this diagram are the zone locations; these zones locations are standard for all buildings according to ASCE 7.

   

“Building Information” requirements are explained one by one.  (By running your cursor over the top of each description you will be given information, stated from ASCE 7, that helps you with your entries.  This information is provided on each program for quick and easy reference, but can also be found in the ASCE 7 book; in Chapter 6).

              All the “Building Information” is entered, next is to find the wind loads for the roof, door(s), and window(s).

1. Wind Velocity: The number entered in this cell is to have the units

    in miles per hour (mph). This is the velocity zone

   location that your building is located, according to 

   the ASCE 7 Basic Wind Speed Map. The map is

   provided with the purchase of your programs.

2. Building Category: Make your selection from the pull-down list. The

   options are provided in the description given on the

   program (place cursor over the top of the

   description.) If you need more information on

   Building Categories, please reference Table 1-1 in

   the ASCE 7 book.

3. Importance Factor: The value is automatically calculated for you, based

   on your “Building Category” entry. You can view

   the values of the Importance Factor from the

   “Building Category” description; when placing your

   cursor over the top of the description.

4. Exposure: From the pull-down list you have three (3) choices.

   Exposures B, C, & D. (Exposure A was eliminated

   after ASCE 7-98). Make your selections based on

   the information that is provided is the description.

   (The description provided is the same description

   you will find in ASCE 7).

5. Internal Pressure: Make your selection from the pull-down list

   provided. You have three (3) choices. 1) Partially

   Enclosed, 2) Enclosed Building, 3) Open Building.

     a. Partially Enclosed: This type of building has

          walls under the roof, but also has at least one

          side that is exposed or open to the outside.

     b. Enclosed: This is the most common. This type

          of building has no openings exposed to the

          outside. The walls enclose the entire building

          under the roof.

      c. Open Building: This type of structure has no

          walls under the roof, and is completely exposed

          to the outside. This would basically be a roof

          that is only supported by post, pillars or similar

          supports.

6. Height Above Ground: This is also know as the value “z”. This value is for

   elevated buildings, for the simple fact that the value

   of “z” is the dimension from the ground to the

   bottom of your building. So if your building is at

   ground level, this value would be zero (0).

7. Standard Wall Height: This value is the dimension measured from the

   ground to the eave height (or where the lower

   portion of your roof meets the side-wall) of your

   building.

8. Mean Roof Height: This also known as the value “h”. This value is the

   dimension measured from grade to the average of

   the roof eave height and the highest point on the

   roof surface, except that eave height shall be used

   for the roof angle if it is less than or equal to 10

   degrees.

   Remember: When h > 60 ft., your roof angle must

   be less than or equal to 10 degrees; according to the

   ASCE 7.

   Flat Roofs: This will be the actual building height

   value.

9. Building Width: This value is the width dimension of your building;

   in feet.

10. Building Length: This value is the length dimension of your building;

   in feet.

11. Roof Slope: This is the value of “x” over twelve; or x/12. You

      need to enter a value from 0-12 (Zero (0) is flat, and

      twelve (12) is 45 degrees).

12. Roof Angle: This value is automatically calculated and entered

      for you. It displays the angle of your roof based on

      the value of “x” entered for your roof’s slope.

13. Edge Strip: This value is also known as the value of “a”. This

      value is automatically calculated based off of the

      building information you entered. The Edge Strip

      value (“a”), is used to determine the dimensions of

      zone five (5) for your wall sections, and zone (3) for

      your roof sections.

14. End Zone: This value is the total Edge Strip value along one

      side of your wall. This value is also automatically

      calculated for you, based off of the building

      information you entered in. It is basically the value

      of “a” multiplied by two (2).  

 

Below is a diagram that shows the garage that we are finding wind loads for.  As you can see the numbers below show the zones for the garage.

  

Note:

  1. Zones 1, 2, & 3 are always applied to the roof.
    1. Zone 3: are the edge or corner sections; always equal to the value of “a”.
    2. Zone 2: are the perimeter sections; minus the Zone 3 (edge/corner) areas.
    3. Zone 1: are the interior sections.  Basically the interior area left over after subtracting the areas of the Zone 3, and Zone 2.
  2. Zones 4 & 5 are always applied to the walls.
    1. Zone 5: are the corner sections; always equal to the value of “a”.
    2. Zone 4: are the interior sections; or the area remaining after subtracting the Zone 5 sections.
  3. Remember: The Value of “a” is always applied to the roof and wall corners.
  4. Remember: Any door or window dimension that falls within the area of “a” (edge/corner = Zone 5) section must have the Zone 5 applied to it.
  5. Remember: Any opening dimension that falls with the area of “a” (edge/corner = Zone 3) on the roof (such as a sky-light) must have the Zone 3 applied to it.


Finding Roof Wind Loads:

First find the dimension (from center-to-center) of your roof’s truss frames.  For this example our truss frames are dimensioned 3 feet from center-to-center (Reference the diagram below).  Building Length is 30ft, and the value of “a” (Edge Strip) is 3 feet.

 

From this we can determine the areas with our Zones 1, 2, & 3.

Below is a diagram that shows the zones with their respective areas.

  

Zone 3                                                 = (Value of “a”) x (Value of “a”)

                                                = (3 feet) x (3 feet)

                                                = 9 square feet.

 

Zone 2 (Perimeter)                               = (Truss Frame: center-to-center) x (Value of “a”)

(Width & Length)                 = (3 feet) x (3 feet)

(Eave Areas)                           = 9 square feet.

 

Zone 2 (Perimeter)                               = (Value of “a”) x (Trigonometry)

(Width & Length)                 = (3 feet) x (9 feet)

(Ridge Areas)                         = 27 square feet.

 

Zone 2 (Perimeter: Length Side)           = (Value of “a”) x (Trigonometry)

(Width & Length)                     = (3 feet) x (4.5 feet)

(Eave & Ridge Areas)              = 13.5 square feet

Note: Program calculates the precise number, but shows the effective area on the program rounded up.

 

Zone 1 (Interior: Width Side)                = (Truss Frame: center-to-center) x (Trigonometry)

                                                                     = (3 feet) x (4.28 feet)

                                                                     = 12.84 square feet

 

Zone 1 (Interior: Length Side)               = (Truss Frame: center-to-center) x (Dimension between Zone 2)

                                                                     = (3 feet) x (3.5 feet)

                                                                     = 10.5 square feet

Zone 1 (Interior: Length Side)              = (Truss Frame: center-to-center) x (Trigonometry)

                                                                    = (3 feet) x (1.75 feet)

                                                            = 5.25 square feet

 

It is not necessary to calculate for each individual area for the zones on the roof since they are equally distributed, meaning the following applies:

Ø      All of the areas for Zone 3 = 9 sqft.

Ø      Reference the color coded roof image on the previous page.


Finding Wall Wind Loads for Window & Doors:

For this example we have:

Window A:       Side Window   = W x H = (5 feet x 3 feet)       = 15 square feet

Door B:            Garage Door    = W x H = (16 feet x 8 feet)     = 128 square feet

Door C:            Entrance Door  = W x H = (3 feet x 7 feet)       = 21 square feet

 

Note:    The “Opening Elevation” is the dimension measured from the ground to the center point of the opening.  The following diagrams show how to determine the “Opening Elevation” for the garage door and the windows.

We are now able to enter in all the information into the Windloadcalc.com Program.  The following page is the computed spreadsheet.


 

 


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