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, 2026

Dear Fellow Stockholders,

Today’s Limbach is a fundamentally different and stronger company than it was even a few years ago. We are building a higher-margin, cash generative solutions-led platform, positioned to deliver durable growth and superior long-term stockholder returns. Our strategy is clear, our momentum is real, and our confidence in Limbach’s trajectory has never been higher.

In 2026, Limbach marks its 125 th year of continuous operation, a milestone achieved by fewer than 100 U.S. public companies 1. While our team celebrates this long legacy, we know that longevity demands adaptability, disciplined execution, and the ability to evolve as markets change. Our strategy has been to carve our own path as a leading building systems solutions firm that serves as a trusted partner, solving our customers’ most complex problems.

Delivering What We Promised

2025 was a pivotal inflection point in validating our strategic plan for sustainable growth. Following an outstanding 2024, our team delivered another record year of financial results. Revenue for the year reached a record $646.8 million, an increase of 24.7% year over year, while adjusted EBITDA 2 grew 28.4% to $81.8 million, also a company record.

Central to this performance was the continued execution of our Owner Direct Relationships, or ODR, strategy. In 2025, ODR represented approximately 75% of total revenue, achieving our multi-year target. ODR revenue grew 40.6% for the year, including 17% organic growth 3, reflecting increased customer engagement, bundled solutions, and expanded wallet share across mission-critical facilities.

Cash generation remained a hallmark of our execution. For the year, we delivered strong operating and free cash flow. We ended 2025 with a net debt to Adjusted EBITDA ratio of 0.3x 3. We evaluate capital allocation through a disciplined framework, prioritizing investments that offer the highest risk-adjusted returns. Our acquisition of Pioneer Power and our $50 million share repurchase authorization reflect this approach; driving growth, return of capital, and balance sheet strength.

Why We Win — Limbach Operates in Environments Where Failure Is Not An Option

By design, we focus on critical end markets such as healthcare, industrial and manufacturing, data centers, life sciences, higher education, and cultural and entertainment. Limbach’s scale, technical knowledge, and local execution position us as the long-term partner of choice in this evolving landscape.

Our customers depend on us to ensure ongoing operations, efficiency, and safety. Our unique ability to design, optimize, deliver and maintain customer engineered solutions for Mechanical, Electrical, Plumbing & Control, or MEPC, systems create both speed-to-market and cost certainty advantages. These capabilities position Limbach as a critical partner in environments where downtime is unacceptable and execution risk must be minimized. Increasingly, customers rely on us for more essential work in their critical facilities and engage with us much earlier in their planning process.

1 Morgan Stanley Investment Management Counterpoint Global.

2 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 non-cash items or expenses that are unusual or non-recurring that we believe do not reflect our core operating results. Our board of directors and executive management team focus on Adjusted EBITDA as a key performance and compensation measure. Adjusted EBITDA assists us in comparing our performance over various reporting periods on a consistent basis because it removes from our operating results the impact of certain items that do not necessarily reflect our core operations. 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. In addition, we use Adjusted EBITDA as a component in assessing our net leverage ratio, which we define as total debt less cash and cash equivalents, divided by trailing twelve-month Adjusted EBITDA, as a measure of our balance sheet strength, financial flexibility and capacity to support disciplined capital allocation. A reconciliation of Adjusted EBITDA to the most comparable GAAP measure is provided in Annex A.

3 A reconciliation of these non-GAAP components can be found in our earnings press release filed on Form 8-K with the SEC on March 3, 2026.

Growth, Guided by Discipline

Our growth strategy is anchored by three pillars. First, we aim to grow total revenue and ODR organic revenue, while maintaining a stable mix between ODR and General Contractor Relationships, or GCR, revenue. We are combining national scale with local execution, to better serve mission-critical facilities. Additionally, we are investing both at the local and national level to accelerate sales, leverage SG&A and drive earnings growth.

To bolster our national growth strategy, in January 2026, we announced two Executive Vice President appointments for national customer solutions and sales. These roles centralize national customer strategy, sales execution, and cross-branch coordination which are key to scaling our ODR relationships.

Our second pillar is to expand margins through evolved customer solutions. We differentiate ourselves by serving as a single-source provider for building owners, delivering comprehensive life-cycle engineered solutions. The third pillar is strategic M&A aimed at extending the reach of the Limbach brand, strengthening our market presence and expanding our capabilities.

In July 2025, we completed the acquisition of Pioneer Power for approximately $66 million, our largest acquisition to date. The transaction meaningfully expanded our presence in the Upper Midwest, enhanced our industrial and mission-critical capabilities, and further scaled our ODR model. We share a highly compatible culture and approach to risk management, and above all, a total commitment to optimizing customers’ facilities through value-enhancing systems solutions.

Our immediate focus is on integrating operations and unlocking value by applying our proven value creation strategies to grow market share among core customers, improve gross margins over time, and deepen customer relationships.

Looking Ahead: Built to Endure, Positioned to Lead

Very few companies last 125 years. Even fewer do so while actively reshaping their business model for growth. Limbach’s longevity gives us credibility—but our strategy, execution, and capital discipline are what position us to create value going forward. We are focused on building a business that not only endures, but compounds value over time through consistent execution and disciplined decision-making. Looking ahead to 2026, we will continue to build on our strong foundation. Our priorities remain clear: grow top-line revenue through organic growth focused on ODR and disciplined M&A, improve margins, and continue to allocate capital with a focus on delivering long-term stockholder value.

On behalf of our Board of Directors and the entire Limbach team, 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 9, 2026

The 2026 Annual Meeting of Stockholders of the Company will be held on Tuesday, June 9, 2026, 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, 2026, the record date for the Annual Meeting. The Notice of Annual Meeting, the Proxy Statement, the accompanying proxy card and our 2025 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 Joshua S. Horowitz, Linda G. Alvarado and Terence P. Dugan as Class A 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 hold a non-binding advisory vote on the frequency of future advisory votes on the compensation of our named executive officers;

4. To ratify the appointment of Crowe LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026; and

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

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 8, 2026 atwww.meetnow.global/MZGQJXG. 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, 2026 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, 2026

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE

ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON JUNE 9, 2026

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

TABLE OF CONTENTS

PROXY STATEMENT

FOR THE 2026 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on June 9, 2026

This Proxy Statement is being furnished to our stockholders of record as of the close of business on April 17, 2026 in connection with the solicitation by our Board of Directors of proxies for the 2026 Annual Meeting of Stockholders (the “Annual Meeting”) to be held solely by remote communication in a virtual-only format on Tuesday, June 9, 2026, 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, 2026.

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.