> For the complete documentation index, see [llms.txt](https://docs.paragontruss.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.paragontruss.com/design/reference/analysis-settings-reference.md).

# Analysis Settings Reference

This page describes each setting in the **Analysis Settings** panel and what it affects. Analysis settings control the parameters Paragon uses when it analyzes a component against the building code and TPI 1. The building code and TPI 1 (and the engineer of record) are authoritative — these descriptions explain what each setting changes in Paragon, not which value your project requires. Where a setting corresponds to a code clause, the clause is named so you can consult the source.

For how to open and edit the panel, see [Analysis Settings](/design/how-to/general/modify-project-and-component-settings/analysis-settings.md).

{% hint style="info" %}
The panel subtitle shows the **Design Standard** (the TPI 1 edition), which is determined by the building code selected in [Load Settings](/design/reference/load-settings.md). A few settings change their default, their behavior, or the TPI section they cite depending on that edition; those cases are noted below. Which deflection-limit sections appear also depends on whether a roof truss, a floor truss, or project-wide defaults are selected.
{% endhint %}

## Deflection Limits

When a single component is selected, this section is titled **Deflection Limits** and shows the limits for that truss type. When project-wide defaults are edited (or a non-component selection is active), separate **Roof Deflection Limits** and **Floor Deflection Limits** sections appear.

Limits are organized into two load categories — **Live Loads** and **Total Loads** — and, within each, by the structural element they apply to. Each element offers up to two limits:

### Span/Deflection ratio

Sets the deflection limit as a span-to-deflection ratio (e.g., 240 means span ÷ 240). You can pick a listed value or type your own.

The values offered in the dropdown differ by element and category (for example, Live-load truss/chord limits start at 240/180 options while cantilever and overhang options start lower), but any ratio can be entered directly.

### Absolute (inches)

Sets the deflection limit as an absolute distance, in inches. The governing limit is the more restrictive of the ratio and absolute limits.

The element rows are:

* **Truss** — the overall span deflection of the truss.
* **TC Panel** — deflection of a top-chord panel between joints.
* **BC Panel** — deflection of a bottom-chord panel between joints.
* **Cantilever** — deflection at a cantilever.
* **Overhang** — deflection at an overhang.
* **Web** — deflection of a web member.
* **Horizontal** — horizontal deflection limit; offered as an absolute (inches) limit only.
* **Attic Room Floor** — appears under **Live Loads** for roof trusses only; limits deflection of the floor of an attic room defined within the truss.

### Link to Floor Truss Limits

When this is on, changing the attic room floor deflection limits will also change the overall deflection limits for floor trusses and vice versa.

It appears with the **Attic Room Floor** row when editing project-wide defaults.

## Multi Ply Settings

### Connection Type

Selects how the plies of a multi-ply truss are fastened together — **Nailed** or **Screwed** — which determines the fastening capacity used in analysis.

If a nailed connection is selected for a truss whose total ply thickness exceeds 4½ inches, a warning is shown: *The total thickness is greater than 4 1/2 inches and therefore likely too much for nails.*

## Chord Bracing

Bracing is configured separately for each chord — **Sloped Top Chord**, **Flat Top Chord**, and **Bottom Chord** — and determines the unbraced length used in the chord's buckling checks. Each chord offers the same controls:

### Is Sheathed

When on, the chord is treated as continuously braced by sheathing, so purlin spacing does not apply.

### Use Max Purlin Spacing

When on, the chord is braced at the maximum purlin spacing Paragon calculates for it rather than a spacing you enter. It is unavailable when the chord is sheathed.

### Purlin Spacing

Sets the spacing of the purlins (bracing points) along the chord. It is labeled "Maximum Spacing" when *Use Max Purlin Spacing* is on, and is unavailable when the chord is sheathed.

### Calculated Max Purlin Spacing

Reports the maximum purlin spacing Paragon computed for the chord. The value is read-only and appears only when a single component is selected.

## Plating Settings

### JSI Limit

Sets the maximum allowable Joint Stress Index, between 0 and 1.

### Compressive Force Reduction (C<sub>R</sub>)

Sets the plate compressive-force reduction factor used in plate checks, between 0 and 1.

### Fabrication Tolerance for Front-Back Plates — %

This determines the quality control factor for front-back plates. 1 minus this value is C<sub>q</sub>.

### Fabrication Tolerance for Top-Bottom Plates — %

This determines the quality control factor for top-bottom plates. 1 minus this value is C<sub>q</sub>.

### Required Lateral Bite

Sets the lateral bite required of plates, used in the lateral bite check. The value is limited to 6 inches.

### Add Plates Along Stacks & Max Plate Interval

Adds plates where necessary along stacked members to achieve the specified maximum spacing. This can help to satisfy composite action modeling assumptions if the "Assume Composite Action for Stacked Members" setting is on. See TPI 1 Section 7.3.3.7.

Turn on **Add Plates Along Stacks** to enable the **Max Plate Interval** distance (default 30 inches, per TPI 1 Section 7.3.3.7).

### Plate Ribbon Blocks

When on, plates are added to ribbon blocks.

### Heel Plate Min Width / Heel Plate Min Length

These set the minimum width and length used for heel plates.

### Peak Plate Min Width / Peak Plate Min Length

Minimum plate dimensions for peak plates apply when a positive slope is adjacent to a negative slope (i.e., at peak joints).

### Try Off-Center Plate Shifts

When on, plating may shift a plate away from its joint center — further onto the member that is over capacity — before trying a larger plate. The setting is off by default.

Shifts are only attempted at a joint whose plate checks fail and where exactly one member is over capacity. Candidate shifts move the plate toward that member in 1/8-inch steps, smallest shift first, up to half the plate's extent in the shift direction; the first candidate that satisfies the plate checks is used. A candidate is discarded if the shifted plate would stop covering every member at the joint, leave a physical joint uncovered, overlap another plate at the joint, or fall outside the truss boundary. The shifts apply to rectangular front-back plates, and a plate whose placement is anchored to a member edge can only slide along that edge.

## Other Settings

### Use Wet Service Factor (C<sub>M</sub>)

This factor is applicable when lumber moisture content will exceed 19% for an extended period of time or at time of fabrication. See TPI 1 Section 6.4.6.

### Use Bending Modification Factor (K<sub>m</sub>)

This factor is applicable to bending capacity F<sub>b</sub> in check TPI 1 Section 7.3.5 calculations, and applies only to sawn lumber. See TPI 1 Section 6.4.3 for caveats.

### Use Repetitive Member Increase (C<sub>r</sub>)

Increases design values for axial force and bending checks. It may be applicable when 3 or more trusses are joined by sheathing/flooring and spaced no more than 2 ft. on center. See TPI 1 Section 6.4.2 for caveats.

### Assume Composite Action for Stacked Members

Treats stacked members as having greater bending stiffness than the sum of the stiffnesses of the layers. TPI 1 Section 7.3.3.7 specifies how to do this for two-layer stacks with sufficient plating. This setting applies the same specification to all stacked members.

### Pin End Vertical Joints (Roof Trusses)

Causes roof truss joints involving end verticals (or other similar joints) to be treated as pinned rather than semi-rigidly or rigidly connected.

The setting applies to roof trusses. Under TPI 1-2022 and later it defaults to on; see TPI 1 Section 6.1.1.3.2(e).

### Use Manual Camber & Manual Camber

Overrides the camber on the Truss Design Drawing.

Turn on **Use Manual Camber** to enter the **Manual Camber** distance.

### Creep Factor (K<sub>cr</sub>)

This factor is applied to long-term deflections. It should be at least 2 for dry service conditions, and at least 3 for wet service conditions.

### Incising Factor (C<sub>i</sub>)

This adjustment accounts for lumber incising, used in some preservative-treated lumber, and applies to design values for some member strength checks. See TPI 1 Section 6.4.8.

### Temperature Range

Harsher temperatures at the installation site require design value reductions. See TPI 1 Section 6.4.7 & Table 6.4-5.

The options are **T < 100°F**, **100°F ≤ T < 125°F**, and **125°F ≤ T < 150°F**.


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