Predictika · Composite decking

An AI sales agent's decking order, checked before it goes out

An AI sales agent prepares a composite decking order: the decking line, profile, length and colour, how far apart the joists are, how the boards are gapped and overhang the edge, and the stairs. Before it goes out, the agent sends it to Predictika, which checks it against a declarative model of what the public Trex Decking Installation Guide says and returns a verdict, every reason and the figures it computed.

Scope: Trex decking boards: listed line, profile, length and colour, joist spacing by use and board angle, gaps, overhang and stairs. See everything this validator covers

This validator models a Trex decking order based on the rules and tables in the public Trex Decking Installation Guide, not just the scenarios shown below.

  • Boards — the line (Signature, Lineage, Tropicals, Earth Tones, Select, Naturals, Basics), profile (square-edge 1x6, grooved 1x6, square-edge 2x6), length and colour must be a combination the guide lists. Island Mist Tropicals was discontinued, Select cannot be mixed with other lines, and Signature, Naturals and Basics cannot be curved.
  • Framing — the maximum joist spacing on center depends on the board profile, the use (residential, commercial 100 psf, commercial 200 psf) and the board angle (90, 60, 45 or 30 degrees); each board must span at least 3 joists. The maximum the quote states must equal the guide.
  • Gaps and overhang — width-to-width gaps of 3 to 8 sixteenths of an inch, end-to-end gaps of at least 2 sixteenths (3 below 40 degrees F), and an overhang of at most 3/4 inch.
  • Stairs — at least 36 inches wide, 4 stringers (5 above 36 inches), stringer spacing of at most 12 inches (9 inches for Select, Naturals and Basics 1x6 boards), treads at least 11 inches deep with a 4 to 6 sixteenths gap and an overhang of at most 3/4 inch.
  • Approvals — heavy items such as hot tubs or planters need span recommendations from a local building engineer or inspector, so a person confirms them.

Any Trex decking order that touches these rules is in scope — not only the scenarios pictured here. Not covered: prices (Trex program pricing to dealers and distributors is not public, so this page shows no price build-up), railing, fascia and accessories, and fastener and hidden-clip details.

The AI sales agentBuilds the decking order from the conversation and says it is ready.
Predictika validatorChecks every rule at once and returns the verdict, each finding, and the computed figures.

7 scenarios in 3 groups · each group runs from the agent’s first attempt to the outcome · click one to switch

What the agent proposes

The AI sales agent says

Illustrative agent statement. The validator receives the structured request below.

Proposing agent: AI sales agent (scripted)

Before sending, the agent must call Recorded run

Predictika validator


      

        
        
        
      

      
Waiting for the call.

      
    

  

  
  

    
Where rules-based CPQ gets it wrong
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Our assessment of what a typical rules-based CPQ (product rules, price rules and validation rules, as in Salesforce CPQ) does with the same cases. It is a judgment about effort and reliability, not a claim that nothing can be built.

    
What the validator caughtTypical rules-based CPQPredictika
Joist spacing that depends on profile, use and board angleOnly with care
The maximum spacing is a table of profile, use and angle, so a rules-based CPQ needs a rule or table row for each combination and an adjustment for the angle.		The table is inside the model and the spacing is computed on every call.
Boards listed only in some line, profile, length and colour combinationsOnly with workarounds
A compatibility table or one rule per board, edited again whenever the guide or the product range changes.		The listed combinations are a table inside the model, and an unlisted board is found on every call.
Limits that change with the installation temperatureOnly with care
The end gap depends on a temperature threshold, so a rule must read the temperature and pick the gap.		The temperature and the gap are compared together with all other checks.
Stairs whose limits depend on stair width and boardOnly with care
Stringer count depends on width, and stringer spacing on the board, each a rule across lines.		The width, board and stair figures arrive in one request and are checked together.
Every problem returned in one answerOnly with workarounds
Rules tend to fire as the quote is saved or a step is completed, so a person often fixes one error and meets the next.		All findings come back together, whatever order the choices arrived in.

  

  

    
What this validator catches: findings from its test cases
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Every rule is checked on every call, in any order the choices arrive; one problem never hides another. Blocking findings stop the quote; approval findings need a person to sign off; everything else is computed.

    
1The Trex guide lists no board of the selected line and profile in a length of 16 feet.
2The Trex guide lists no board of the selected line and profile in a length of 12 feet.
3The selected colour is not listed in the Trex guide for the selected decking line.
4The Trex guide says Island Mist Tropicals was discontinued on 12.31.2024 and replaced by Transcend Lineage Island Mist.
5The Trex guide says not to combine Trex Select decking with other Trex decking products, because Select boards are thinner.
6The Trex guide says Trex Signature and Trex Enhance decking cannot be curved.
7Joists are spaced 17 inches on center; the maximum for this board, use and board angle is 16 inches.
8Joists are spaced 25 inches on center; the maximum for this board, use and board angle is 24 inches.
9Joists are spaced 13 inches on center; the maximum for this board, use and board angle is 12 inches.
10Joists are spaced 15 inches on center; the maximum for this board, use and board angle is 14 inches.
11Joists are spaced 9 inches on center; the maximum for this board, use and board angle is 8 inches.
12Each board must span at least 3 joists; the quote has 2.
13A width-to-width gap of 2 sixteenths of an inch is outside the guide range of 3/16 to 1/2 inch (3 to 8 sixteenths).
14A width-to-width gap of 9 sixteenths of an inch is outside the guide range of 3/16 to 1/2 inch (3 to 8 sixteenths).
15An end-to-end gap of 1 sixteenth of an inch is below the 2 sixteenths the guide requires at the installation temperature.
16An end-to-end gap of 2 sixteenths of an inch is below the 3 sixteenths the guide requires at the installation temperature.
17An overhang of 13 sixteenths of an inch is above the 3/4 inch (12 sixteenths) maximum.
18A stairway 35 inches wide is below the 36 inch minimum width.
19The stairs have 4 stringers; the guide requires 5 for this width.
20Stair stringers are spaced 12 inches on center; the maximum for this board is 9 inches.

  

  

    
Scenarios and results
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The recorded result of the validator for each scenario on this page: the request the AI agent sent, the verdict, and every finding, in the order they appear above.

    
1. Boardwalk in Island Mist Tropicals: Commercial boardwalk in discontinued Island Mist Tropicals 2x6 with joists 24 inches apart

    
The agent's request. Please quote Transcend Tropicals square-edge 2x6 decking in Island Mist in a length of 16 feet for a commercial 200 psf deck, boards laid at 90 degrees, with joists 24 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 70 degrees F, with an overhang of 8 sixteenths. The quote states a maximum joist spacing of 24 inches. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Island Mist Tropicals discontinued. The Trex guide says Island Mist Tropicals was discontinued on 12.31.2024 and replaced by Transcend Lineage Island Mist.
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  • Joists spaced too far apart. Joists are spaced 24 inches on center; the maximum for this board, use and board angle is 16 inches.
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  • Stated joist spacing does not match. The quote states a maximum joist spacing of 24 inches; the guide gives 16 inches for this board, use and angle.
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2. Boardwalk in Island Mist Tropicals: The agent resubmits after fixing the errors

    
The agent's request. Please quote Transcend Tropicals square-edge 2x6 decking in Tiki Torch in a length of 16 feet for a commercial 200 psf deck, boards laid at 90 degrees, with joists 16 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 70 degrees F, with an overhang of 8 sixteenths. The quote states a maximum joist spacing of 16 inches. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • Order summary. Joists may be spaced up to 16 inches on center for this board, use and angle; the quote has 16.
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3. Angled deck installed in the cold: Lineage deck at 45 degrees installed at 30 degrees F with a small gap and a long overhang

    
The agent's request. Please quote Transcend Lineage grooved 1x6 decking in Rainier in a length of 16 feet for a residential deck, boards laid at 45 degrees, with joists 16 inches on center and each board spanning 4 joists. Gaps are 2 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 30 degrees F, with an overhang of 14 sixteenths. The quote states a maximum joist spacing of 16 inches. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Joists spaced too far apart. Joists are spaced 16 inches on center; the maximum for this board, use and board angle is 12 inches.
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  • Width-to-width gap out of range. A width-to-width gap of 2 sixteenths of an inch is outside the guide range of 3/16 to 1/2 inch (3 to 8 sixteenths).
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  • End-to-end gap too small. An end-to-end gap of 2 sixteenths of an inch is below the 3 sixteenths the guide requires at the installation temperature.
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  • Overhang too long. An overhang of 14 sixteenths of an inch is above the 3/4 inch (12 sixteenths) maximum.
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  • Stated joist spacing does not match. The quote states a maximum joist spacing of 16 inches; the guide gives 12 inches for this board, use and angle.
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4. Angled deck installed in the cold: The agent resubmits after fixing the errors

    
The agent's request. Please quote Transcend Lineage grooved 1x6 decking in Rainier in a length of 16 feet for a residential deck, boards laid at 45 degrees, with joists 12 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 30 degrees F, with an overhang of 12 sixteenths. The quote states a maximum joist spacing of 12 inches. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • End-to-end gap too small. An end-to-end gap of 2 sixteenths of an inch is below the 3 sixteenths the guide requires at the installation temperature.
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5. Angled deck installed in the cold: The agent resubmits after fixing the errors

    
The agent's request. Please quote Transcend Lineage grooved 1x6 decking in Rainier in a length of 16 feet for a residential deck, boards laid at 45 degrees, with joists 12 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 3 sixteenths end to end, installed at 30 degrees F, with an overhang of 12 sixteenths. The quote states a maximum joist spacing of 12 inches. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • Order summary. Joists may be spaced up to 12 inches on center for this board, use and angle; the quote has 12.
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6. Select deck with stairs and a hot tub: Select deck with wide stairs, too few stringers and a shallow tread, plus a hot tub

    
The agent's request. Please quote Select grooved 1x6 decking in Pebble Grey in a length of 16 feet for a residential deck, boards laid at 90 degrees, with joists 16 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 70 degrees F, with an overhang of 8 sixteenths, with a stairway 48 inches wide, 4 stringers 12 inches on center, treads 10 inches deep with a gap of 4 sixteenths and an overhang of 8 sixteenths and a hot tub on the deck. The quote states a maximum joist spacing of 16 inches. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Too few stair stringers. The stairs have 4 stringers; the guide requires 5 for this width.
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  • Stair stringers spaced too far apart. Stair stringers are spaced 12 inches on center; the maximum for this board is 9 inches.
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  • Stair tread too shallow. A stair tread 10 inches deep is below the 11 inch minimum.
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  • Heavy items need a building engineer. The guide says heavy items such as hot tubs or planters need span recommendations from a local building engineer or inspector; a person should confirm them.
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7. Select deck with stairs and a hot tub: The agent resubmits after fixing the errors

    
The agent's request. Please quote Select grooved 1x6 decking in Pebble Grey in a length of 16 feet for a residential deck, boards laid at 90 degrees, with joists 16 inches on center and each board spanning 4 joists. Gaps are 3 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 70 degrees F, with an overhang of 8 sixteenths, with a stairway 48 inches wide, 5 stringers 9 inches on center, treads 11 inches deep with a gap of 4 sixteenths and an overhang of 8 sixteenths and a hot tub on the deck. The quote states a maximum joist spacing of 16 inches. It is ready to send.

    
Verdict: Needs approval.

    
    
      
  • Heavy items need a building engineer. The guide says heavy items such as hot tubs or planters need span recommendations from a local building engineer or inspector; a person should confirm them.
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  • Order summary. Joists may be spaced up to 16 inches on center for this board, use and angle; the quote has 16.
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Narration transcript
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The text of the narrated walkthrough, step by step.

    
    
      
  1. Welcome to a demo of Predictika's Validator. An AI sales agent prepares a composite decking order: the decking line, profile, length and colour, and more. Before it goes out, the agent sends it to Predictika, which checks it against a declarative model of what the public Trex Decking Installation Guide says and returns a verdict, every reason and the figures it computed.
    2. 
      
  2. I will start with the first request by the agent.
    3. 
      
  3. The agent says. Please quote Transcend Lineage grooved 1x6 decking in Rainier in a length of 16 feet for a residential deck, boards laid at 45 degrees. Gaps are 2 sixteenths of an inch width to width and 2 sixteenths end to end, installed at 30 degrees F, with an overhang of 14 sixteenths. The rest of the request is on screen.
    4. 
      
  4. Before it goes out, the agent calls the validator.
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  5. Blocked, with five findings, all in one answer. Joists are spaced 16 inches on center; the maximum for this board, use and board angle is 12 inches. A width-to-width gap of 2 sixteenths of an inch is outside the guide range of 3/16 to 1/2 inch (3 to 8 sixteenths). An end-to-end gap of 2 sixteenths of an inch is below the 3 sixteenths the guide requires at the installation temperature. The other two are on screen.
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  6. The validator returned five blocking findings in one answer. A check that reads one field at a time would pass most of this; it shows only when the choices in the quote are checked against each other.
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  7. What this shows: for joist spacing that depends on profile, use and board angle, a rules-based CPQ is error-prone for this.
    8. 
      
  8. Now the agent resubmits.
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  9. The corrected request. It changes the joist spacing on center to 12 in, the width-to-width gap to 3 sixteenths of an inch, the overhang to 12 sixteenths of an inch and the stated maximum joist spacing as to 12 in.
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  10. It calls the validator again.
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  11. Still blocked, with one finding, all in one answer. An end-to-end gap of 2 sixteenths of an inch is below the 3 sixteenths the guide requires at the installation temperature.
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  12. Four findings cleared. Still blocking: end-to-end gap too small.
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  13. The agent resubmits once more.
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  14. The revised request. It changes the end-to-end gap to 3 sixteenths of an inch.
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  15. It calls the validator once more.
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  16. This time the validator clears it.
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  17. The earlier finding is cleared, and the validator's figure matches the quote.
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  18. Five problems caught in one call, fixed in two passes, and a clean quote. That is the value of Predictika's validator: catching mistakes before they reach the customer. Now you can try the other scenarios yourself.
    19.