Cover Page - shares	6 Months Ended
	Mar. 31, 2023	Apr. 28, 2023
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2023
Document Period End Date	Mar. 31, 2023
Current Fiscal Year End Date	--09-30
Entity Registrant Name	AZEK Co Inc.
Entity Central Index Key	0001782754
Entity File Number	001-39322
Entity Tax Identification Number	90-1017663
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Incorporation, State or Country Code	DE
Entity Emerging Growth Company	false
Entity Address, Address Line One	1330 W Fulton Street, Suite 350
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60607
City Area Code	877
Local Phone Number	275-2935
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	AZEK
Security Exchange Name	NYSE
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		150,932,386
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		100