Add or Modify a Wood I-Joist and Plywood or OSB Decking Floor System

This dialog can be used to:

  1. define and add a "wood I-joist and plywood or OSB decking floor system" assembly to a project, or
  2. modify or view "wood I-joist and plywood or OSB decking floor system" assembly that has been added to a project.
  3. define an envelope for this assembly.
Description / Assumptions / Limits Required inputs

Wood I & Plywood / OSB decking

  • Solid wood joists supporting decking. The design is based on joists at 600mm o.c. Bridging is not included.
  • Various options exist to define the characteristics of I joist webs and flange members
  • Web type (plywood, OSB)
  • Web thickness (9.5, 12mm)
  • Flange type (MSR, LVL)
  • Flange size (38x38mm, 63x38mm, 89x38mm)
  • Design span range limits:
    • 3.6m - 12.2m for 2.4kPa loads
    • 3.05m - 9.76m for 3.6kPa loads
    • 3.6m - 7.0m for 4.8kPa loads
    (Note: 19mm is the typical decking thickness for most applications)
  • Floor width must be greater than zero.
  • Span must be greater than zero for all loads. If an entered span is less than the minimum value, a minimum span of 3.05m or 3.6m is used for calculating material requirements. The material requirements are then factored by multiplying the material requirements quantities by the entered span divided by the minimum span.
  • Name
  • Floor width (m)
  • Span (m)
  • Decking type (Plywood, OSB)
  • Thickness (12, 15, 19 mm)
  • Live load (2.4, 3.6, 4.8 kPa)

 

Seismic Note:

Seismic adjustments include extra nails along the decking edges and blocking at each end of the joist.

 

Field Descriptions:

Name:
Enter a name for this assembly. All assemblies within a project must be uniquely named within each assembly group. Names maybe alphanumeric (e.g., floor 1).

Floor Width:
Enter the floor width in m or ft. The floor width is calculated as follows: Total Floor Area / Supported Span = Floor Width. The user must enter this floor width, in m or ft.

Span:
The Span determines the size of I-joist needed.  Enter the maximum span (within the constraints above) of your assembly, in m or ft.  i.e.: If an assembly consists of three rows of repeating 5.0 m spans, the user should enter a span 5.0 m and adjust the Floor Width in order to achieve the desired Floor Area.

*See Important Note below regarding Span and Width entries.

Decking Type:
Click a radio button to select either plywood or OSB decking materials.
  • Plywood
  • OSB

Decking Thickness:
Click a radio button to select a decking thickness for the assembly in mm or inches.
  • 12 mm (1/2 in.)
  • 15 mm (5/8 in.)
  • 19 mm (3/4 in.)

Live Load:
Click a radio button to select the live load to be carried by this column and beam assembly system.
  • 2.4 kPa (50 psf) represents a typical roof load for a typical office / residential occupancy condition (above the first floor)
  • 3.6 kPa (75 psf) represents a typical mechanical/service room loading
  • 4.8 kPa (100 psf) would be indicative of heavier floor loads such as assembly areas, balconies/mezzanines, corridors, lobbies/exit areas and storage areas.

I-Joist Type:
Click the radio buttons to select the make-up of the truss to be employed ( e.g., select the web thickness of the joist and type (plywood or OSB), the flange size and type (Machine stress rated lumber or laminated veneer lumber).
  • 2.4 kPa (50 psf) represents a typical roof load for a typical office / residential occupancy condition (above the first floor)
  • 3.6 kPa (75 psf) represents a typical mechanical/service room loading
  • 4.8 kPa (100 psf) would be indicative of heavier floor loads such as assembly areas, balconies/mezzanines, corridors, lobbies/exit areas and storage areas.

The I-Joist Type is defined using the following information:

Web Thickness:
  • 9.5 mm (3/8 in)
  • 12 mm (1/2 in)

Web Type:
  • Plywood
  • OSB

Flange Size:
  • 38 x 38 mm (1.5 x 1.5 in)
  • 63 x 38 mm (2.5 x 1.5 in)
  • 89 x 38 mm (3.5 x 1.5 in)

Flange Type:
  • MSR
  • LVL

Units:
Here you can set the units of measure as either "SI" or "Imperial". Changing the default units here affects only the current assembly but will not override the Default Units of Measure nor the Units of Measure settings for open projects or any other assemblies within open projects.

Floor Area (m2 or ft2) Note:
As a user friendly check, the total floor area calculated by the application (as per the users input) is reported in the bottom left hand corner of the dialog box.

Duplicate Button
Click the "Duplicate" button to create an exact duplicate of the current assembly. The duplicate assembly will be added to the current project. This button is only available when editing or viewing an assembly that has already been saved in the current project.

Delete Button
Click the "Delete" button to delete the current assembly from the current project. This button is only available when editing or viewing an assembly that has already been saved in the current project.

Help Button:
Click the "Help" button to open the Help pop-up window.

OK Button
Click the "OK" button to accept and save the current assembly settings and close this dialog.

Cancel Button
Click the "Cancel" button to discard the current assembly settings and close this dialog.

 

Important Note:

With Floor assemblies, the critical input is the Span. This should be the maximum span that the assembly will be subjected to, and it will determine the size of the assembly needed. For example, in a concrete suspended slab floor, the span will determine how thick the slab needs to be. The Width is used to account for the total area of the assembly, and may not be the actual width of the assembly. The following Figure 1 shows an actual floor as designed (the yellow floor assembly), and Figure 2 shows how that assembly must be modelled in Impact Estimator (the red equivalent assembly). Notice that the equivalent assembly's width has been changed so the total area of the assembly stays the same, and the span is entered to reflect the maximum span (between the first two rows of beams).

Figure 1

FloorSpan1

Figure 2

FloorSpan2