Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 10, 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	Jun. 30, 2019
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2019
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		6,007,791
Entity File Number	001-38037
Entity Address, Address Line One	195 Montague Street,
Entity Address, City or Town	Brooklyn
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	11201
Entity Tax Identification Number	954463937
City Area Code	(646)
Local Phone Number	240-4235