Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation References in these financial statements to the Company refer collectively to the accounts of Limbach Holdings, Inc. and its wholly-owned subsidiaries, including Limbach Holdings LLC (“LHLLC”), Limbach Facility Services LLC (“LFS”), Limbach Company LLC (“LC LLC”), Limbach Company LP, (“LC LP”), Harper Limbach LLC (“Harper”), Harper Limbach Construction LLC (“Harper Construction LLC”), Limbach Facility & Project Solutions LLC (“LFPS”), Jake Marshall, LLC (“JMLLC”), Coating Solutions, LLC (“CSLLC”), ACME Industrial Piping, LLC (“ACME”), Industrial Air, LLC (“Industrial Air”), Kent Island Mechanical, LLC (“Kent Island”) and Consolidated Mechanical, LLC (“Consolidated Mechanical”) for all periods presented, unless otherwise indicated. All intercompany balances and transactions have been eliminated. The accompanying unaudited condensed consolidated financial statements were prepared using generally accepted accounting principles (“GAAP”) for interim financial information and with the requirements of Form 10-Q and applicable rules of Regulation S-X of the Securities and Exchange Commission (“SEC”). Consequently, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. Readers of this report should refer to the consolidated financial statements and the notes thereto included in the Company's most recent Annual Report on Form 10-K filed with the SEC on March 10, 2025.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements for assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, the reported amounts of revenue and expenses during the reported period, and the accompanying notes. Management believes that its most significant estimates and assumptions have been based on reasonable and supportable assumptions and the resulting estimates are reasonable for use in the preparation of the condensed consolidated financial statements. The Company’s significant estimates include estimates associated with revenue recognition on construction contracts, costs incurred through each balance sheet date, intangibles, property and equipment, fair value accounting for acquisitions, insurance reserves, income tax valuation allowances, fair value of contingent consideration arrangements and contingencies. If the underlying estimates and assumptions upon which the condensed consolidated financial statements are based change in the future, actual amounts may differ from those included in the accompanying condensed consolidated financial statements.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying interim Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Stockholders’ Equity and Condensed Consolidated Statements of Cash Flows for the periods presented are unaudited. Also, within the notes to the condensed consolidated financial statements, the Company has included unaudited information for these interim periods. These unaudited interim condensed consolidated financial statements have been prepared in accordance with GAAP. In the Company's opinion, the accompanying unaudited condensed consolidated financial statements contain all normal and recurring adjustments necessary for a fair statement of the Company’s financial position as of March 31, 2025, its results of operations and equity for the three months ended March 31, 2025 and 2024 and its cash flows for the three months ended March 31, 2025 and 2024. The results for the three months ended March 31, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025. The Condensed Consolidated Balance Sheet as of December 31, 2024 was derived from the Company's audited financial statements included in its Annual Report on Form 10-K filed with the SEC on March 10, 2025, but is presented as condensed and does not contain all of the footnote disclosures from the annual financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, and in January 2025, the FASB issued ASU 2025-01, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date. ASU 2024-03 requires additional disclosure of the nature of expenses included in the income statement as well as disclosures about specific types of expenses included in the expense captions presented in the income statement. ASU 2024-03, as clarified by ASU 2025-01, is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Companies have the option to apply this guidance either on a retrospective or prospective basis, and early adoption is permitted. The Company is currently evaluating the impact that the adoption of these standards will have on its condensed consolidated financial statements and disclosures. In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures (Topic 740). This update requires entities to disclose additional information with respect to the effective tax rate reconciliation and to disclose the disaggregation by jurisdiction of income tax expense and income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company expects to adopt this standard in its 2025 Form 10-K. This standard will not have an impact on the Company's consolidated financial position, results of operations or cash flows, but will affect its financial statement disclosures as discussed above. In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity and amends the scope guidance for contracts in an entity's own equity. The ASU addresses how convertible instruments are accounted for in the calculation of diluted earnings per share by using the if-converted method. The guidance is effective for all entities for fiscal years beginning after March 31, 2024, albeit early adoption is permitted no earlier than fiscal years beginning after December 15, 2020. The Company has adopted this pronouncement and concluded that there’s no impact on the Company’s condensed consolidated financial statements.
Revenue from Contract with Customers	Revenue from Contracts with Customers The Company generates revenue from construction-type contracts, primarily consisting of fixed-price contracts, to deliver mechanical, plumbing, and electrical construction services to its customers. The duration of its contracts generally ranges from three months to two years. Revenue from fixed price contracts is recognized on the cost-to-cost method, measured by the relationship of total cost incurred to total estimated contract costs. Revenue from time and materials contracts is recognized as services are performed. The Company believes that its extensive experience in mechanical, plumbing, and electrical projects, and its internal cost review procedures during the bidding process, enable it to reasonably estimate costs and mitigate the risk of cost overruns on fixed price contracts. The Company generally invoices customers on a monthly basis, based on a schedule of values that breaks down the contract amount into discrete billing items. Costs and estimated earnings in excess of billings on uncompleted contracts are recorded as a contract asset until billable under the contract terms. Billings in excess of costs and estimated earnings on uncompleted contracts are recorded as a contract liability until the related revenue is recognizable. The Company classifies contract assets and liabilities that may be settled beyond one year from the balance sheet date as current, consistent with the length of time of the Company’s project operating cycle. Retainage receivable represents amounts invoiced to customers where payments have been partially withheld, typically 10%, pending the completion of certain milestones, satisfaction of other contractual conditions or the completion of the project. Retainage agreements vary from project to project and balances could be outstanding for several months or years depending on a number of circumstances such as contract-specific terms, project performance and other variables that may arise as the Company makes progress towards completion. Contract assets represent the excess of contract costs and profits (or contract revenue) over the amount of contract billings to date and are classified as a current asset. Contract assets result when either: (1) the appropriate contract revenue amount has been recognized over time in accordance with ASC Topic 606, but a portion of the revenue recorded cannot be currently billed due to the billing terms defined in the contract, or (2) costs are incurred related to certain claims and unapproved change orders. Claims occur when there is a dispute regarding both a change in the scope of work and the price associated with that change. Unapproved change orders occur when a change in the scope of work results in additional work being performed before the parties have agreed on the corresponding change in the contract price. The Company routinely estimates recovery related to claims and unapproved change orders as a form of variable consideration at the most likely amount it expects to receive and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Claims and unapproved change orders are billable upon the agreement and resolution between the contractual parties and after the execution of contractual amendments. Increases in claims and unapproved change orders typically result from costs being incurred against existing or new positions; decreases normally result from resolutions and subsequent billings. Billings in excess of costs and estimated earnings on uncompleted contracts represent the excess of contract billings to date over the amount of contract costs and profits (or contract revenue) recognized to date. The balance may fluctuate depending on the timing of contract billings and the recognition of contract revenue. Provisions for losses are recognized in the condensed consolidated statements of operations at the uncompleted performance obligation level for the amount of total estimated losses in the period that evidence indicates that the estimated total cost of a performance obligation exceeds its estimated total revenue. Remaining Performance Obligations Remaining performance obligations represent the transaction price of firm orders for which work has not been performed and exclude unexercised contract options. The Company’s remaining performance obligations include projects that have a written award, a letter of intent, a notice to proceed or an agreed upon work order to perform work on mutually accepted terms and conditions. Additionally, the difference between remaining performance obligations and backlog is due to the exclusion of a portion of the Company’s ODR agreements under certain contract types from the Company’s remaining performance obligations as these contracts can be canceled for convenience at any time by the Company or the customer without considerable cost incurred by the customer.
Fair Value Measurements	The Company measures the fair value of financial assets and liabilities in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures, which defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to measurements involving significant unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows: •Level 1 — inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that are accessible at the measurement date; •Level 2 — inputs other than quoted prices included in Level 1 that are observable for the asset or liability either directly or indirectly such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities; and •Level 3 — unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2025

References in these financial statements to the Company refer collectively to the accounts of Limbach Holdings, Inc. and its wholly-owned subsidiaries, including Limbach Holdings LLC (“LHLLC”), Limbach Facility Services LLC (“LFS”), Limbach Company LLC (“LC LLC”), Limbach Company LP, (“LC LP”), Harper Limbach LLC (“Harper”), Harper Limbach Construction LLC (“Harper Construction LLC”), Limbach Facility & Project Solutions LLC (“LFPS”), Jake Marshall, LLC (“JMLLC”), Coating Solutions, LLC (“CSLLC”), ACME Industrial Piping, LLC (“ACME”), Industrial Air, LLC (“Industrial Air”), Kent Island Mechanical, LLC (“Kent Island”) and Consolidated Mechanical, LLC (“Consolidated Mechanical”) for all periods presented, unless otherwise indicated. All intercompany balances and transactions have been eliminated.

The accompanying unaudited condensed consolidated financial statements were prepared using generally accepted accounting principles (“GAAP”) for interim financial information and with the requirements of Form 10-Q and applicable rules of Regulation S-X of the Securities and Exchange Commission (“SEC”). Consequently, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. Readers of this report should refer to the consolidated financial statements and the notes thereto included in the Company's most recent Annual Report on Form 10-K filed with the SEC on March 10, 2025.

Use of Estimates

The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements for assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, the reported amounts of revenue and expenses during the reported period, and the accompanying notes. Management believes that its most significant estimates and assumptions have been based on reasonable and supportable assumptions and the resulting estimates are reasonable for use in the preparation of the condensed consolidated financial statements. The Company’s significant estimates include estimates associated with revenue recognition on construction contracts, costs incurred through each balance sheet date, intangibles, property and equipment, fair value accounting for acquisitions, insurance reserves, income tax valuation allowances, fair value of contingent consideration arrangements and contingencies. If the underlying estimates and assumptions upon which the condensed consolidated financial statements are based change in the future, actual amounts may differ from those included in the accompanying condensed consolidated financial statements.

Unaudited Interim Financial Information

The accompanying interim Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations, Condensed Consolidated Statements of Stockholders’ Equity and Condensed Consolidated Statements of Cash Flows for the periods presented are unaudited. Also, within the notes to the condensed consolidated financial statements, the Company has

included unaudited information for these interim periods. These unaudited interim condensed consolidated financial statements have been prepared in accordance with GAAP. In the Company's opinion, the accompanying unaudited condensed consolidated financial statements contain all normal and recurring adjustments necessary for a fair statement of the Company’s financial position as of March 31, 2025, its results of operations and equity for the three months ended March 31, 2025 and 2024 and its cash flows for the three months ended March 31, 2025 and 2024. The results for the three months ended March 31, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025.

The Condensed Consolidated Balance Sheet as of December 31, 2024 was derived from the Company's audited financial statements included in its Annual Report on Form 10-K filed with the SEC on March 10, 2025, but is presented as condensed and does not contain all of the footnote disclosures from the annual financial statements.

Recent Accounting Pronouncements

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, and in January 2025, the FASB issued ASU 2025-01, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date. ASU 2024-03 requires additional disclosure of the nature of expenses included in the income statement as well as disclosures about specific types of expenses included in the expense captions presented in the income statement. ASU 2024-03, as clarified by ASU 2025-01, is effective for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Companies have the option to apply this guidance either on a retrospective or prospective basis, and early adoption is permitted. The Company is currently evaluating the impact that the adoption of these standards will have on its condensed consolidated financial statements and disclosures.

In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures (Topic 740). This update requires entities to disclose additional information with respect to the effective tax rate reconciliation and to disclose the disaggregation by jurisdiction of income tax expense and income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company expects to adopt this standard in its 2025 Form 10-K. This standard will not have an impact on the Company's consolidated financial position, results of operations or cash flows, but will affect its financial statement disclosures as discussed above.

In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity and amends the scope guidance for contracts in an entity's own equity. The ASU addresses how convertible instruments are accounted for in the calculation of diluted earnings per share by using the if-converted method. The guidance is effective for all entities for fiscal years beginning after March 31, 2024, albeit early adoption is permitted no earlier than fiscal years beginning after December 15, 2020. The Company has adopted this pronouncement and concluded that there’s no impact on the Company’s condensed consolidated financial statements.

Revenue from Contract with Customers

Revenue from Contracts with Customers

The Company generates revenue from construction-type contracts, primarily consisting of fixed-price contracts, to deliver mechanical, plumbing, and electrical construction services to its customers. The duration of its contracts generally ranges from three months to two years. Revenue from fixed price contracts is recognized on the cost-to-cost method, measured by the relationship of total cost incurred to total estimated contract costs. Revenue from time and materials contracts is recognized as services are performed. The Company believes that its extensive experience in mechanical, plumbing, and electrical projects, and its internal cost review procedures during the bidding process, enable it to reasonably estimate costs and mitigate the risk of cost overruns on fixed price contracts.

The Company generally invoices customers on a monthly basis, based on a schedule of values that breaks down the contract amount into discrete billing items. Costs and estimated earnings in excess of billings on uncompleted contracts are recorded as a contract asset until billable under the contract terms. Billings in excess of costs and estimated earnings on uncompleted contracts are recorded as a contract liability until the related revenue is recognizable. The Company classifies contract assets and liabilities that may be settled beyond one year from the balance sheet date as current, consistent with the length of time of the Company’s project operating cycle.

Retainage receivable represents amounts invoiced to customers where payments have been partially withheld, typically 10%, pending the completion of certain milestones, satisfaction of other contractual conditions or the completion of the project. Retainage agreements vary from project to project and balances could be outstanding for several months or years depending on a number of circumstances such as contract-specific terms, project performance and other variables that may arise as the Company makes progress towards completion.

Contract assets represent the excess of contract costs and profits (or contract revenue) over the amount of contract billings to date and are classified as a current asset. Contract assets result when either: (1) the appropriate contract revenue amount has been recognized over time in accordance with ASC Topic 606, but a portion of the revenue recorded cannot be currently billed due to the billing terms defined in the contract, or (2) costs are incurred related to certain claims and unapproved change orders. Claims occur when there is a dispute regarding both a change in the scope of work and the price associated with that change. Unapproved change orders occur when a change in the scope of work results in additional work being performed before the parties have agreed on the corresponding change in the contract price. The Company routinely estimates recovery related to claims and unapproved change orders as a form of variable consideration at the most likely amount it expects to receive and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Claims and unapproved change orders are billable upon the agreement and resolution between the contractual parties and after the execution of contractual amendments. Increases in claims and unapproved change orders typically result from costs being incurred against existing or new positions; decreases normally result from resolutions and subsequent billings.

Billings in excess of costs and estimated earnings on uncompleted contracts represent the excess of contract billings to date over the amount of contract costs and profits (or contract revenue) recognized to date. The balance may fluctuate depending on the timing of contract billings and the recognition of contract revenue.

Provisions for losses are recognized in the condensed consolidated statements of operations at the uncompleted performance obligation level for the amount of total estimated losses in the period that evidence indicates that the estimated total cost of a performance obligation exceeds its estimated total revenue.

Remaining Performance Obligations

Remaining performance obligations represent the transaction price of firm orders for which work has not been performed and exclude unexercised contract options. The Company’s remaining performance obligations include projects that have a written award, a letter of intent, a notice to proceed or an agreed upon work order to perform work on mutually accepted terms and conditions.

Additionally, the difference between remaining performance obligations and backlog is due to the exclusion of a portion of the Company’s ODR agreements under certain contract types from the Company’s remaining performance obligations as these contracts can be canceled for convenience at any time by the Company or the customer without considerable cost incurred by the customer.

Fair Value Measurements

The Company measures the fair value of financial assets and liabilities in accordance with ASC Topic 820 – Fair Value Measurements and Disclosures, which defines fair value, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to measurements involving significant unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows:

•Level 1 — inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that are accessible at the measurement date;

•Level 2 — inputs other than quoted prices included in Level 1 that are observable for the asset or liability either directly or indirectly such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities; and

•Level 3 — unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.