Crate Pro 6

Technical White Paper

Cleat Rules for Plywood Panels

Cleat Rules determine the existence and placement of Intermediate Cleats on a plywood panel.

Using Cleat Rules to apply Intermediate Cleats will assist you in assuring your cleats are applied over seams and spaced as may be required by a specification or otherwise desired.

Cleat Rules are run automatically when a new Design is created or by clicking the Run Rule button. When creating a new design, Crate Pro will create plywood splices first, then will apply the predetermined Rule based on the splice results. After adjusting splices manually or pressing the Apply button you can run the selected Intermediate Cleat Rule for that panel to reset the cleating arrangement to match the plywood splices, if any. 

The Rule you select will determine if cleating is applied horizontally, vertically, both or not at all.

Selecting the 0 - No Materials Rule will clear all Intermediate Cleat fields and any plywood splice patterns will be ignored. Selecting any other Rule will always apply cleats over splices. So if, for example, you select the V1 - Vertical only Rule while your plywood Pieces reflect that a horizontal splice exists, Crate Pro will calculate and apply vertical cleats but will then also apply horizontal cleats as required to cover the horizontal splices.

Cleat Rules for Plywood Panels are possibly the most useful and comprehensive feature of Crate Pro's design module. Beyond just applying cleats over plywood splices, Crate Pro will space intermediate cleats using a variety of internal data to assure cleating meets the requirements of many published standards for panel support. Clearly understanding how Crate Pro applies cleats will allow you to create designs faster and with more confidence. Further, it is a critical feature in allowing inexperienced users to design basic containers without requiring an engineering review.

Note for Crate Pro 5 users: The Rules as they were used in Crate Pro 5 have been combined and now function more intelligently. Rules in Crate Pro 6 will always look for seams first and apply cleating over seams then will use First/Rest values in all remaining unsupported spans. Manual adjustment of intermediate cleats after running a Rule should no longer be required.

First and Rest: Before learning the rules themselves, it's important to understand how Crate Pro applies spacing.

Most published standards state a maximum distance between cleats which is often known as an Unsupported Span. In the United States that distance is typically 24" (~650mm) however many crate manufacturers do not follow this requirement when designing small containers. To conform to both commercial and published standards, Crate Pro uses First and Rest values.

First: The First value indicates the maximum Unframed Area that is allowed before any intermediate cleats are applied. In Crate Pro's internal calculations this value is only considered once. Once the Unframed Area (span) in the primary direction exceeds this distance, intermediate cleats will be applied. The First value is only considered in the primary direction so if, for example, the Rule is V1 - Verticals first is run, Crate Pro will only consider the horizontal span to determine if cleating should be applied. Crate Pro's default value for First is 36" (1000mm) which is generally accepted in the industry.

Rest: The Rest value is the maximum Unsupported Span allowed after intermediate cleats have been applied. Crate Pro's default Rest value is 24" (~650mm) because this is the maximum Unsupported Span allowed by many published standards. When applicable to a span (vertical or horizontal depending on the selected Rule) Crate Pro will apply enough intermediate cleats to assure all Unsupported Spans are less than or equal to the Rest value.

Since Crate Pro will apply cleats on every plywood splice, it's known that an Unsupported Span will often be less than the dimension of a piece of plywood minus 50% of the width of a cleat. Since a crate panel can be comprised of up to nine different sizes of plywood (refer to the Plywood Rules white paper) and various sizes of cleats (and other considerations), Crate Pro has to follow guidelines to determine the cleat Item to apply for intermediate cleats. Further, to minimize the number of cut-off saw stops required during manufacturing, Crate Pro must standardize the distance between cleats while applying them to various sizes of Unsupported Spans on a panel. Before presenting how spacing is determined and where cleats are placed, it's helpful to understand the Rules themselves. 

Crate Pro has six different Plywood Panel Cleat Rules that can apply intermediate cleats. They are:

  • Vertical only

    On Top Panels and Base Panels, Vertical refers to Front-to-Aft and Horizontal refers to Left-to-Right

    Vertical first
  • Horizontal only
  • Horizontal first
  • Divide greatest span only
  • Divide greatest span first

(Review the Perspectives and Dimensions white paper to understand the use of 'Vertical' and 'Horizontal')

Vertical only and Horizontal only: These Rules will apply intermediate cleats in the direction specified. After cleats have been placed on plywood splices, Crate Pro will identify the Unframed Area (the distance between Framing Cleats, or the span of the panel if there are no Framing Cleats). If the Unframed Area is greater than the value of First, Crate Pro will apply intermediate cleats until all Unsupported Spans are less than or equal to the value of Rest.

Divide greatest span...:  These Rules will identify the Unframed Area vertically and horizontally then will apply cleats across the shortest distance of the two so as the greatest span becomes divided. As mentioned above, all of the 'only' rules will apply cleats in the opposing direction if there is a plywood splice. Plywood splices are always covered.

Vertical first and Horizontal first: These Rules will apply cleats as stated for the 'only' Rules above then will do the same in the opposing direction. The Unframed Area is only considered for the primary direction so, for example, if a panels Unframed Area is 36.25" (~1001mm) horizontally and is 30" (~750mm) vertically, and the Rule applied is Vertical first, Vertical intermediate cleats will be applied because the Unframed Area horizontally is greater than the value of First (36" (~1000mm)). Because the span of the primary dimension exceeded the value of First and the vertical Unframed Area exceeds the value of Rest, a set of horizontal cleats will also be applied.

Crate Pro doesn't create drawings so the intermediate cleat placement in the Vertical only example above is only theoretical. There is nothing to control where the assembler actually positions the cleats. In the Vertical first example shown above, the length of the horizontal cleats will force the placement of the vertical cleats to a specific position.

Standard Cleat: Crate Pro uses the Leading Vertical Cleat Item for all intermediate cleats that are applied as the result of a Rule. If the Leading Vertical Cleat field is empty, Crate Pro will attempt to identify and use an existing Framing Cleat for that panel. If that's not available, it will refer to the Material Group used when the design was created. If Crate Pro cannot identify an appropriate cleat Item to use then all intermediate cleats will be cleared. You can overcome this by simply entering an Item in the Vertical Leading Cleat field before running the Rule. The Item that Crate Pro identifies and then applies to the panel is termed the Standard Cleat. Because none, any or all of the intermediate cleat fields may already contain an Item when you run a Rule, Crate Pro needs to identify a standard width for cleats so spans can properly be calculated.

The power of Crate Pro's Cleat Rules can best be displayed with the following two diagrams.

This first diagram displays a fairly common plywood splice adjustment. In this case, the rightmost piece was too narrow to meet the minimum requirements so Crate Pro's Plywood Rule increased the width of the rightmost piece then decreased the width of the leftmost piece by the same value.

The Cleat Rule has 1) placed cleats over all seams; 2) identified that the Unframed Area is larger than the First value; 3) identified a Standard Span by selecting what it believes is the most common sized panel; 3) Applied more vertical cleats until no Unsupported Span exceeds the Rest value;  4) Identified if horizontal cleats have been or need to be added, then add them following the same guidelines; 5) assured no cleat's length is less than its width and that no cleats overlap the framing cleats.

This diagram shows a conflict. At 200" (~5100mm) wide the panel above requires no special adjustments. However, at 194" (~5000mm) the Leading Horizontal Cleat's length is less than its width. (For this example, we're assuming 3.5" (~100mm) wide cleats.) This result is unacceptable so Crate Pro will adjust the quantities and lengths of the horizontal cleats as required for a uniform fit while always minimizing the number of required cut-off saw stops.

This situation is only an issue when cleats are placed in the secondary direction. The quantity and length of cleats in the first direction are never affected.


The examples displayed above assume plywood splices exist and represent some of the more complex situations that can occur. Panels that do not include plywood splices are much simpler for Crate Pro to process and simpler to understand. If a panel has no splices, Crate Pro will simply space all Intermediate Cleats evenly assuring that all Unsupported Spans are the same distance. If cleats are applied in the secondary direction they will all be the same length.

Cleats on base panels are limited. Cleating (framing and intermediate) are only available on light-duty plywood containers. To assure proper base support, only one length of intermediate cleat is allowed in each direction.

All of the situations presented above are calculated automatically by Crate Pro's Rules.

Crate Pro 6 does not create panel drawings. 

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