Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 12, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	SG BLOCKS, INC.
Entity Central Index Key	0001023994
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		6,007,791
Entity File Number	001-38037
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Trading Symbol	SGBX
Entity Address, Address Line One	195 Montague Street,
Entity Address, Address Line Two	14<sup>th</sup> Floor,
Entity Address, City or Town	Brooklyn
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	11201
Entity Tax Identification Number	95-4463937
City Area Code	(646)
Title of 12(b) Security	Common Stock, par value $0.01
Security Exchange Name	NASDAQ
Local Phone Number	240-4235