Limbach Holdings, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Name of Registrant as Specified In Its Charter)

April 23, 2025

Dear Stockholders,

Limbach Holdings completed another year of strong execution and record profitability in 2024, driven by our commitment to creating value for our customers and delivering sustainable growth for our investors. Our performance was anchored by the three pillars of our strategy: shifting our revenue mix, evolving our offerings, and scaling through acquisitions.

Executing Our Three-Pillar Strategy

The key to our strategy has been our first pillar – shifting our revenue mix to working directly with building owners on existing infrastructure in the Owner Direct Relationships (“ODR”) segment rather than relying on new construction projects in the General Contractor Relationships (“GCR”) segment. In 2024, approximately 67% of our total revenue came from the ODR segment, contributing approximately 75% of total gross profit dollars. This shift has significantly enhanced our margin profile and has helped to reduce our overall risk.

The second pillar of our strategy involves the evolution of our offerings to expand capabilities and drive higher margins. In 2024, we achieved a meaningful increase in total gross margin to 27.8%, up from 23.1% in 2023. This improvement reflects our commitment to providing engineered solutions that solve complex facility challenges while improving operational efficiencies.

Our third pillar is scaling our business through acquisitions. In 2024, we successfully completed two strategic acquisitions – Kent Island Mechanical and Consolidated Mechanical – which we expect to contribute approximately $6 million to our adjusted EBITDA in 2025. Acquisitions have played a key role in broadening our market reach and strengthening our position in mission-critical verticals*.

Expanding in Key Market Verticals

Our disciplined approach focuses on six mission-critical market verticals that drive consistent demand across economic cycles. Among these, healthcare is our largest and most significant vertical. We play a crucial role in ensuring the operational continuity of medical facilities, allowing them to deliver life-saving care. Each of our 20 locations prioritizes healthcare facilities with acute care, and we continue to expand our national footprint in this sector, developing reoccurring revenue streams as we strengthen our customer relationships and provide onsite account management as well as staff augmentation in certain instances.

Industrial and Manufacturing has become our second largest vertical, driven by our strategic acquisitions. We partner with facility owners to support complex systems, ensuring manufacturing processes run smoothly. Our tailored solutions address regulatory compliance, supply chain resilience, and infrastructure upgrades. By working as a trusted partner, we help customers optimize their operations and facility performance.

*With respect to the projected 2025 Adjusted EBITDA contribution from Kent Island Mechanical and Consolidated Mechanical, a quantitative reconciliation is not available without unreasonable efforts due to the forward-looking nature and high variability, complexity and low visibility with respect to certain items, which are excluded from Adjusted EBITDA. We expect the variability of these items to have a potentially unpredictable, and potentially significant, impact on future financial results. We define Adjusted EBITDA as net income plus depreciation and amortization expense, interest expense, and taxes, as further adjusted to eliminate the impact of, when applicable, other items or expenses that are unusual or non-recurring that we believe do not reflect our core operating results. We believe that Adjusted EBITDA is meaningful to our investors to enhance their understanding of our financial performance for the current period and our ability to generate cash flows from operations that are available for taxes, capital expenditures and debt service. We understand that non-GAAP financial measures are frequently used by securities analysts, investors and other interested parties as a measure of financial performance and to compare our performance with the performance of other companies that report Adjusted EBITDA. Our calculations of non-GAAP measures, however, may not be comparable to similarly titled measures reported by other companies. Our projection of this 2025 Adjusted EBITDA contribution is forward looking; see the statements related to forward looking statements under the heading “Cautionary Note Regarding Forward-Looking Statements” in our Form 10-K for the year ended December 31, 2024 filed with the SEC on March 10, 2025.

We continue to see significant growth opportunities across our other four key verticals as existing buildings age and require critical upgrades to maintain optimal conditions. Our unique value proposition lies in our ability to embed dedicated teams within customer facilities, augmenting their staff and ensuring seamless system performance.

Unlike traditional engineering and construction firms focused on new buildings, Limbach serves building owners directly in existing facilities with aging infrastructure. Our approach fosters long-term customer relationships, generating repeatable revenue streams and creating a more resilient business model.

Positioned for Long-Term Success

While 2024 was a year of progress, we are still in the early stages of realizing our full potential. We see ample opportunities for growth, whether through geographic expansion, margin enhancement, or capitalizing on the infrastructure needs of mission-critical facility owners.

With a strong foundation in place, we are confident in our ability to drive sustained value creation for our customers and our stockholders.

Thank you for your continued trust and support.

Sincerely,

Michael M. McCann

President, Chief Executive Officer and Director

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 11, 2025

The 2025 Annual Meeting of Stockholders of the Company will be held on Wednesday, June 11, 2025, at 9:00 a.m. Eastern Daylight Time (“EDT”) solely by remote communication in a virtual-only format (the “Annual Meeting”).

You are entitled to participate in the Annual Meeting if you were a stockholder of the Company as of the close of business on April 17, 2025, the record date for the Annual Meeting. The Notice of Annual Meeting, the Proxy Statement, the accompanying proxy card and our 2024 Annual Report are available on the Company’s website atwww.limbachinc.com under “Investors – Financials.” The Annual Meeting is being held for the following purposes:

1. To elect Michael M. McCann and Laurel J. Krzeminski as Class C members of our Board of Directors, each to serve for a three-year term;

2. To hold a non-binding advisory vote on the compensation of our named executive officers;

3. To transact any other business that properly comes before the Annual Meeting and any adjournment or postponement thereof;

4. To approve an amendment to the Limbach Holdings, Inc. Amended and Restated Omnibus Incentive Plan; and

5. To ratify the appointment of Crowe LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025.

Stockholders will not be able to attend the Annual Meeting in person. Instead, stockholders should follow the instructions provided below to attend the virtual Annual Meeting. Stockholders interested in attending this virtual Annual Meeting are required to register by 11:59 p.m. EDT on June 10, 2025 athttps://web.viewproxy.com/limbach/2025/. The Company urges stockholders to vote and submit proxies in advance of the Annual Meeting by one of the methods described in these proxy materials for the Annual Meeting. Stockholders who attend the virtual Annual Meeting by following the instructions in these proxy materials will have an opportunity to vote and to submit questions electronically during the meeting.

Only stockholders of record as of the close of business on April 17, 2025 are entitled to receive notice of and to vote at the Annual Meeting and any and all adjournments or postponements thereof. Stockholders who hold shares in street name may vote through their brokers, banks or other nominees.

Regardless of the number of shares you own and whether you plan to attend the virtual Annual Meeting, please vote. All stockholders of record can vote (i) over the Internet by accessing the Internet website or QR code specified on the enclosed proxy card or voting instruction form and following the instructions provided to you, (ii) by calling the toll-free telephone number specified on the enclosed proxy card or voting instruction form and following the instructions when prompted, (iii) by written proxy by signing and dating the enclosed proxy card or voting instruction form and returning it, or (iv) by attending the virtual Annual Meeting in accordance with the instructions provided in the Proxy Statement.

We encourage you to receive all proxy materials in the future electronically to help us save printing costs and postage fees, as well as natural resources in producing and distributing these materials. If you wish to receive these materials electronically in the future, please follow the instructions on the proxy card or voting instruction form.

By Order of the Board of Directors,

/s/ Michael M. McCann

Michael M. McCann

President, Chief Executive Officer and Director

April 23, 2025

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE

ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON JUNE 11, 2025

our website at www.limbachinc.com under “Investors — Financials”

TABLE OF CONTENTS

PROXY STATEMENT

FOR THE 2025 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 11, 2025

This Proxy Statement is being furnished to our stockholders of record as of the close of business on April 17, 2025 in connection with the solicitation by our Board of Directors of proxies for the 2025 Annual Meeting of Stockholders (the “Annual Meeting”) to be held solely by remote communication in a virtual-only format on Wednesday, June 11, 2025, at 9:00 a.m. EDT, or at any and all adjournments or postponements thereof, for the purposes stated in the Notice of Annual Meeting of Stockholders. The approximate date of mailing of this Proxy Statement and the enclosed form of proxy is April 23, 2025.

Unless we state otherwise or the context otherwise requires, references in this Proxy Statement to “we,” “our,” “us,” or the “Company” are to Limbach Holdings, Inc. a Delaware corporation.