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Trex Co. Inc. – ‘10-Q’ for 9/30/22 – ‘EX-101.DEF’

On:  Monday, 10/31/22, at 5:24pm ET   ·   For:  9/30/22   ·   Accession #:  1193125-22-274084   ·   File #:  1-14649

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  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

10/31/22  Trex Co. Inc.                     10-Q        9/30/22   73:5.5M                                   Donnelley … Solutions/FA

Quarterly Report   —   Form 10-Q

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML   1.34M 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     24K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     24K 
 4: EX-32       Certification -- §906 - SOA'02                      HTML     22K 
10: R1          Cover Page                                          HTML     73K 
11: R2          Condensed Consolidated Statements of Comprehensive  HTML     90K 
                Income                                                           
12: R3          Condensed Consolidated Balance Sheets               HTML    119K 
13: R4          Condensed Consolidated Balance Sheets               HTML     39K 
                (Parenthetical)                                                  
14: R5          Condensed Consolidated Statements of Changes in     HTML     90K 
                Stockholders' Equity                                             
15: R6          Condensed Consolidated Statements of Cash Flows     HTML     96K 
16: R7          Business and Organization                           HTML     25K 
17: R8          Basis of Presentation                               HTML     27K 
18: R9          Recently Adopted Accounting Standards               HTML     35K 
19: R10         New Accounting Standards Not Yet Adopted            HTML     25K 
20: R11         Inventories                                         HTML     34K 
21: R12         Prepaid Expenses and Other Assets                   HTML     31K 
22: R13         Goodwill and Other Intangible Assets, Net           HTML     24K 
23: R14         Accrued Expenses and Other Liabilities              HTML     34K 
24: R15         Debt                                                HTML     36K 
25: R16         Leases                                              HTML     47K 
26: R17         Financial Instruments                               HTML     24K 
27: R18         Stockholders' Equity                                HTML     64K 
28: R19         Revenue From Contracts With Customers               HTML     75K 
29: R20         Stock-Based Compensation                            HTML     54K 
30: R21         Income Taxes                                        HTML     28K 
31: R22         Segment Information                                 HTML     69K 
32: R23         Seasonality                                         HTML     24K 
33: R24         Commitments and Contingencies                       HTML     53K 
34: R25         Summary of Significant Accounting Policies          HTML     25K 
                (Policies)                                                       
35: R26         Inventories (Tables)                                HTML     33K 
36: R27         Prepaid Expenses and Other Assets (Tables)          HTML     31K 
37: R28         Accrued Expenses and Other Liabilities (Tables)     HTML     33K 
38: R29         Leases (Tables)                                     HTML     47K 
39: R30         Stockholders' Equity (Tables)                       HTML     59K 
40: R31         Revenue From Contracts With Customers (Tables)      HTML     68K 
41: R32         Stock-Based Compensation (Tables)                   HTML     53K 
42: R33         Segment Information (Tables)                        HTML    102K 
43: R34         Commitments and Contingencies (Tables)              HTML     44K 
44: R35         Business and Organization - Additional Information  HTML     23K 
                (Detail)                                                         
45: R36         Inventories - Summary of Inventories (Detail)       HTML     31K 
46: R37         Inventories - Additional Information (Detail)       HTML     25K 
47: R38         Prepaid Expenses and Other Assets - Summary of      HTML     33K 
                Prepaid Expenses and Other Assets (Detail)                       
48: R39         Goodwill and Other Intangible Assets, Net -         HTML     38K 
                Additional Information (Detail)                                  
49: R40         Accrued Expenses and Other Liabilities - Summary    HTML     37K 
                of Accrued Expenses and Other Liabilities (Detail)               
50: R41         Debt - Additional Information (Detail)              HTML     58K 
51: R42         Leases - Additional Information (Detail)            HTML     32K 
52: R43         Leases - Supplemental Cash flow Information to      HTML     37K 
                operating leases (Details)                                       
53: R44         Leases - Maturities of Operating Lease Liabilities  HTML     40K 
                (Details)                                                        
54: R45         Stockholders' Equity - Additional Information       HTML     26K 
                (Detail)                                                         
55: R46         Stockholders' Equity - Computation of Basic and     HTML     64K 
                Diluted Earnings Per Share (Detail)                              
56: R47         Stockholders' Equity - Antidilutive Securities      HTML     29K 
                Excluded from Computation of Earnings Per Share                  
                (Detail)                                                         
57: R48         Revenue From Contracts With Customers - Additional  HTML     25K 
                Information (Detail)                                             
58: R49         Revenue From Contracts With Customers - Summary of  HTML     39K 
                Disaggregated Net Sales (Detail)                                 
59: R50         Stock-Based Compensation - Additional Information   HTML     42K 
                (Detail)                                                         
60: R51         Stock-Based Compensation - Summary of Stock-Based   HTML     29K 
                Compensation Grants (Detail)                                     
61: R52         Stock-Based Compensation - Summary of Assumptions   HTML     35K 
                Used to Estimate Fair Value of Each SAR (Detail)                 
62: R53         Stock-Based Compensation - Summary of Stock-Based   HTML     33K 
                Compensation Expenses (Detail)                                   
63: R54         Income Taxes - Additional Information (Detail)      HTML     39K 
64: R55         Segment Information - Additional Information        HTML     23K 
                (Detail)                                                         
65: R56         Segment Information - Details of Segment            HTML     85K 
                Information (Detail)                                             
66: R57         Segment Information - Schedule of Reconciliation    HTML     65K 
                of Net Income to EBITDA (Detail)                                 
67: R58         Commitments and Contingencies - Additional          HTML     42K 
                Information (Detail)                                             
68: R59         Commitments and Contingencies - Summary of          HTML     35K 
                Reconciliation of Company's Residential Product                  
                Warranty Reserve (Detail)                                        
71: XML         IDEA XML File -- Filing Summary                      XML    130K 
69: XML         XBRL Instance -- d347630d10q_htm                     XML   1.30M 
70: EXCEL       IDEA Workbook of Financial Reports                  XLSX    109K 
 6: EX-101.CAL  XBRL Calculations -- trex-20220930_cal               XML    119K 
 7: EX-101.DEF  XBRL Definitions -- trex-20220930_def                XML    417K 
 8: EX-101.LAB  XBRL Labels -- trex-20220930_lab                     XML    831K 
 9: EX-101.PRE  XBRL Presentations -- trex-20220930_pre              XML    644K 
 5: EX-101.SCH  XBRL Schema -- trex-20220930                         XSD    130K 
72: JSON        XBRL Instance as JSON Data -- MetaLinks              330±   476K 
73: ZIP         XBRL Zipped Folder -- 0001193125-22-274084-xbrl      Zip    197K 


‘EX-101.DEF’   —   XBRL Definitions — trex-20220930_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
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4 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 7/12/22  Trex Co. Inc.                     8-K:1,9     7/07/22   11:13M                                    Donnelley … Solutions/FA
 5/09/22  Trex Co. Inc.                     10-Q        3/31/22   75:4.4M                                   Donnelley … Solutions/FA
 8/02/21  Trex Co. Inc.                     10-Q        6/30/21   75:5.2M                                   Donnelley … Solutions/FA
 5/01/19  Trex Co. Inc.                     8-K:5,9     5/01/19    3:108K                                   Donnelley … Solutions/FA
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