Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.10.0.1
Document and Entity Information - shares
3 Months Ended
Dec. 31, 2018
Feb. 08, 2019
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Dec. 31, 2018  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Trading Symbol ROAD  
Entity Registrant Name Construction Partners, Inc.  
Entity Central Index Key 0001718227  
Current Fiscal Year End Date --09-30  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company true  
Entity Small Business true  
Entity Ex Transition Period true  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding (in shares)   11,950,000
Class B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding (in shares)   39,464,619