Document and Entity Information	3 Months Ended
	Jul. 31, 2018 shares
Document and Entity Information
Entity Registrant Name	GMS Inc.
Entity Central Index Key	0001600438
Document Type	10-Q
Document Period End Date	Jul. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--04-30
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	41,138,634
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1