Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-38009
Entity Registrant Name	FOUNDATION BUILDING MATERIALS, INC.
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001688941
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-4259606
Entity Address, Address Line One	2520 Red Hill Avenue
Entity Address, City or Town	Santa Ana,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92705
City Area Code	714
Local Phone Number	380-3127
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock
Trading Symbol	FBM
Security Exchange Name	NYSE
Entity Common Stock Shares Outstanding		43,207,120