Company: LGN
Filing Date: 2025-12-11
Form Type: S-1MEF
Source: 0001193125-25-316548
Chunk: 1

Company: Legence Corp.
Filing Date: 2025-12-11
Form: S-1MEF
Chunk 1
---
 to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-acceleratedfiler, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2of the Exchange Act.

| Large accelerated filer |     | ☐ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☒ |     | Smaller reporting company |     | ☐ |
|                         |     |   |     | Emerging growth company   |     | ☐ |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐ This Registration Statement shall become effective upon filing with the Securities and Exchange Commission in accordance with Rule 462(b) under the Securities Act of 1933, as amended.

EXPLANATORY NOTE AND

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

This registration statement is being filed for the sole purpose of registering 1,612,504 additional shares of Class A common stock par value
$0.01 per share, of the Company (“Class A common stock”) (which includes 210,326 shares of Class A common stock that may be sold as part of the underwriters’ option to purchase additional shares) of Legence Corp., a Delaware
corporation, pursuant to Rule 462(b) under the Securities Act of 1933, as amended. The contents of the registration statement on Form S-1 (File No. 333-292022),
initially filed by Legence Corp. with the Securities and Exchange Commission (the “SEC”) on December 9, 2025, (the “Prior Registration Statement”), and which was declared effective on December 11, 2025, including the exhibits
thereto, are incorporated herein by reference.

The additional securities that are being registered for sale are in an amount and at a
price that together represent no more than 20% of the maximum aggregate offering price