Exhibit
31.3



CERTIFICATION
PURSUANT TO

SECTION
302 OF THE

SARBANES-OXLEY
ACT OF 2002



I,
Paul M. Galvin, certify that:



| | 1. | I have reviewed this Annual Report on  Form 10-K/A of SG Blocks, Inc.;
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| | 2. | Based
on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary
to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect
to the period covered by this report;
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| | 3. | Based
on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material
respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented
in this report;
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| | 4. | The
registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures
(as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange
Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:
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| | a) | Designed
such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision,
to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by
others within those entities, particularly during the period in which this report is being prepared;
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| | b) | Designed
such internal control over financial reporting, or caused such internal control over financial reporting to be designed under
our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial
statements for external purposes in accordance with generally accepted accounting principles;
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| | c) | Evaluated
the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about
the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such
evaluation; and
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| | d) | Disclosed in this
                                                                                                                                                                  report any change in the registrant’s internal control over financial reporting that occurred during the
                                                                                                                                                                  registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report)
                                                                                                                                                                  that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over
                                                                                                                                                                  financial reporting; and
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| | 5. | The
registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over
financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or
persons performing the equivalent functions):
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| | a) | All
significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which
are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information;
and
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| | b) | Any
fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s
internal control over financial reporting.
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Date:
April 15, 2020



| | /s/
    Paul M. Galvin                  
| | ----------------------------------------
| | Paul
    M. Galvin                      
| | Chairman
    and Chief Executive Officer