Presets

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Joist Presets

Joists are repeating members installed at regular spacing, typically 12", 16", or 24" on center.

Common Characteristics

All joist presets share these attributes:

Attribute	Default	Description
spacing	16	Spacing in inches on center
repeat	"Repeating"	Repetition factor applied
LTB_bracing	"Top Braced"	Lateral bracing from sheathing

Load Format

Joists use spacing-based distributed loads:

Code
 
["Label", 0, "L", "spacing", "TW_s", {"D": [psf], "L": [psf]}]

• 0 and "L" = load spans full length
• "spacing" and "TW_s" = tributary width from joist spacing

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Floor Joist

Optimized for repeating floor joists with typical spacing and bracing.

Preset Code: floorJoist

Default Values

Attribute	Value	Description
spacing	16	16" on center
repeat	"Repeating"	Repetition factor
LTB_bracing	"Top Braced"	Top edge braced
LLT	"Occupancy"	Floor live load type
Delta_Span_ST	360	L/360 short-term
Delta_Span_LT	240	L/240 long-term
Delta_Span_DL+LL	180	L/180 simplified
flag_SD	"No"	Simplified deflection off by default

Example

Code
 
{
  "preset": "floorJoist",
  "attributes": {
    "L_X": 14,
    "member": "2x10 D.Fir-L No. 1",
    "supports": [
      ["Pinned", 0, 3.5],
      ["Pinned", 14, 3.5]
    ],
    "loadsDist": [
      ["Floor Load", 0, "L", "spacing", "TW_s", {"D": [10], "L": [40]}]
    ]
  }
}

→ Try in API Reference

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Ceiling Joist

Optimized for ceiling joists with attic storage live load type.

Preset Code: ceilingJoist

Default Values

Attribute	Value	Description
n_com	2	2-ply construction
spacing	16	16" on center
repeat	"Repeating"	Repetition factor
LTB_bracing	"Bottom Braced"	Bottom edge braced
LLT	"Storage"	Attic storage live load
Delta_Span_ST	360	L/360 short-term
Delta_Span_LT	240	L/240 long-term
Delta_Span_DL+LL	180	L/180 simplified
flag_SD	"Yes"	Simplified deflection enabled

Example

Code
 
{
  "preset": "ceilingJoist",
  "attributes": {
    "L_X": 14,
    "member": "2x8 D.Fir-L No. 1",
    "supports": [
      ["Pinned", 0, 3.5],
      ["Pinned", 14, 3.5]
    ],
    "loadsDist": [
      ["Attic Load", 0, "L", "spacing", "TW_s", {"D": [10], "L": [20]}]
    ]
  }
}

→ Try in API Reference

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Deck Joist

Optimized for outdoor deck joists with wet service conditions.

Preset Code: deckJoist

Default Values

Attribute	Value	Description
wet	"Wet"	Wet service (outdoor)
spacing	16	16" on center
repeat	"Repeating"	Repetition factor
LTB_bracing	"Top Braced"	Top edge braced
LLT	"Occupancy"	Deck live load
Delta_Span_ST	360	L/360 short-term
Delta_Span_LT	240	L/240 long-term
Delta_Span_DL+LL	180	L/180 simplified
flag_SD	"Yes"	Simplified deflection enabled
doubleCantileverDeflection	"Yes"	Double limits for cantilevers

Example

Code
 
{
  "preset": "deckJoist",
  "attributes": {
    "L_X": 12,
    "member": "2x8 D.Fir-L No. 2",
    "supports": [
      ["Pinned", 0, 3.5],
      ["Pinned", 12, 3.5]
    ],
    "loadsDist": [
      ["Deck Load", 0, "L", "spacing", "TW_s", {"D": [10], "L": [40]}]
    ]
  }
}

Note: IBC requires minimum 40 psf live load for residential decks (60 psf for balconies serving multiple dwelling units).

→ Try in API Reference

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Rafter

Configured for inclined roof members with gravity loads.

Preset Code: rafter

Default Values

Attribute	Value	Description
incline_flag	"Simple Slope"	Inclined beam
alpha_incline	6	6:12 roof pitch
location_based_on	"Plan"	Locations based on plan length
spacing	16	16" on center
repeat	"Repeating"	Repetition factor
LTB_bracing	"Top Braced"	Top edge braced
LLT	"Occupancy"	Live load type
Delta_Span_ST	180	L/180 short-term
Delta_Span_LT	120	L/120 long-term
Delta_Span_DL+LL	100	L/100 simplified
flag_SD	"Yes"	Simplified deflection enabled
doubleCantileverDeflection	"Yes"	Double limits for cantilevers

Incline-Specific Attributes

Attribute	Type	Description
incline_flag	string	"None", "Simple Slope", or "Hip/Corner Slope"
alpha_incline	number	Roof pitch as rise per 12 run (e.g., 6 = 6:12)
location_based_on	string	"Plan" or "Inclined" length

Example

Code
 
{
  "preset": "rafter",
  "attributes": {
    "L_X": 16,
    "member": "2x10 D.Fir-L No. 1",
    "alpha_incline": 6,
    "spacing": 24,
    "supports": [
      ["Pinned", 0, 3.5],
      ["Pinned", 16, 3.5]
    ],
    "loadsDist": [
      ["Roof Load", 0, "L", "spacing", "TW_s", {"D": [15], "S": [25]}]
    ]
  }
}

→ Try in API Reference

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Next Steps

• Beams - Girders, headers, and combination beams
• Special - Generic, flitch, and hip/valley presets
• Attributes Reference - Complete attribute documentation