Thor Industries : 2021 Proxy Statement Additional Materials

601 East Beardsley Avenue

Elkhart, Indiana 46514

December 2, 2021

Re: THOR Industries, Inc. Proxy Statement for the Annual Meeting of Shareholders to be held December 17, 2021

To the Shareholders of THOR Industries, Inc.:

On November 3, 2021, we filed our definitive proxy statement for our upcoming Annual Meeting of Shareholders, which we refer to as our Annual Meeting, with the Securities and Exchange Commission, which we refer to as the SEC, and provided access to our proxy materials, including our definitive proxy statement, the proxy card and our 2021 Annual Report on Form 10-K, over the Internet.

Proposal 4 on the proxy card for the Annual Meeting relates to our proposal to amend our 2016 Equity and Incentive Plan, which we refer to as the Plan, to increase the number of shares of our common stock available for the grant of awards under the Plan and the maximum number of shares of our Common Stock that can be awarded as Restricted Awards (as defined in the Plan) from 2,000,000 shares to 5,000,000 shares, an increase of 3,000,000 shares. On November 26, 2021, we received a copy of the Proxy Analysis & Benchmark Policy Voting Recommendations issued by Institutional Shareholder Services Inc., or ISS, which we refer to as the Recommendations, relating to our Annual Meeting. In the Recommendations, ISS recommended that our shareholders vote in favor of all of the proposals included in the proxy statement and proxy card for the Annual Meeting, except for Proposal 4 relating to the Plan, as to which ISS recommended a vote against the proposal.

In the Recommendations, ISS noted that the Company's three-year averages for adjusted burn rate (a

measurement of historical grant activity), CEO grants and NEO grants as well as the dilutive effect of the Plan as proposed to be amended were below the median, average and 75th percentile of the Company's 4-digit GICS peer group. Notwithstanding these factors, ISS recommended a vote against Proposal 4. Among the reasons given by ISS for its negative recommendation was its view that cost of the Plan was excessive because the shareholder value transfer, or SVT, represented by (i) the combination of the new shares requested and the available shares remaining under the Plan and (ii) the combination of the new shares requested, the available shares remaining under the Plan and the shares subject to outstanding awards under the Plan exceeded applicable ISS benchmarks.

We are filing additional proxy materials with the SEC and making them available to our shareholders solely for the purpose of addressing the ISS concern regarding the estimated cost of the Plan. In addressing such concern, we first note that, equity compensation has significantly contributed to our growth and success to date, and it is important that we remain able to utilize equity vehicles in the future. Moreover, as reflected by the favorable comparisons to our peer group noted by ISS, we believe we have been good stewards of the Plan shares and have been appropriately judicious in making our award decisions.

After careful consideration of the concerns raised by ISS, our Board of Directors has determined to revise Proposal 4 to reduce the number of new shares requested from 3,000,000 to 1,600,000 and to make a corresponding reduction in the number of shares available for Restricted Awards under the Plan. As a result, if Proposal 4 is approved at the Annual Meeting, the number of shares available for issuance under the Plan and the maximum number of shares that can be awarded as Restricted Awards (including, in each case, shares already issued pursuant to the Plan and shares subject to outstanding awards thereunder) would be increased from 2,000,000 to 3,600,000 shares. A copy of the Plan, as so amended, is attached to our additional proxy materials as Appendix A and replaces the copy of the Plan attached as Appendix Ato our definitive proxy statement.

No other changes were made to Proposal 4 or any other proposals contemplated by our definitive proxy statement and the proxy card for the Annual Meeting as filed with the SEC and previously delivered or otherwise made available to our shareholders of record as of November 3, 2021.

If you have already returned your proxy card or voted over the internet or by telephone, you do not need to vote again unless you wish to change your vote. Your vote will be tabulated as you instructed. If you have not yet voted, please do so as soon as possible by following the instructions set forth in the definitive proxy statement. If you have already returned your proxy card or already voted over the internet or by telephone and wish to change your vote in view of the supplemental information contained herein, you may do so by following the instructions below. You may vote on all the proposals by submitting a proxy card or submitting a proxy via the internet or by telephone by following the procedures previously sent to you. Votes already cast by shareholders will remain valid and will be voted at the 2021 Annual Meeting unless changed or revoked.

THE BOARD OF DIRECTORS RECOMMENDS THAT YOU VOTE "FOR" APPROVAL OF PROPOSAL 4.

Your vote is important. Please carefully consider the information included in our definitive proxy statement, as well as matters discussed in the additional proxy materials, and vote in favor of the proposals included in the definitive proxy statement, including in favor of Proposal 4 relating to the amendment of the Plan (reflecting the amendments discussed in the additional proxy materials).

Our definitive proxy statement, including these additional proxy materials, and our Annual Report on Form 10-K for the fiscal year ended July 31, 2021 are available free of charge at www.proxyvote.comor www.thorindustries.com.

By Order of the Board of Directors,

Todd Woelfer

Senior Vice President and Chief Operating Officer

December 2, 2021

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SUPPLEMENTAL INFORMATION REGARDING PROPOSAL 4: APPROVAL OF AN AMENDMENT TO THE THOR INDUSTRIES, INC. 2016 EQUITY AND INCENTIVE PLAN

Background Regarding Share Reserve Reduction

As described in Proposal 4 of the definitive proxy statement for the 2021 Annual Meeting of Shareholders of THOR Industries, Inc. (the "Company") as filed with the Securities and Exchange Commission on November 3, 2021, we are requesting that our shareholders approve an amendment to the THOR Industries, Inc. 2016 Equity and Incentive Plan (the "plan"). The purpose of the plan is to enable the Company and its affiliates to obtain and retain the services of the types of employees and directors who will contribute to the Company's long range success and to provide incentives that are linked directly to increases in share value which will inure to the benefit of all shareholders of the Company.

After furnishing our definitive proxy statement to our shareholders, we were informed that Institutional Shareholder Services ("ISS") issued an unfavorable recommendation regarding Proposal 4. It is our understanding that ISS issued its recommendation primarily because ISS found the cost of the plan excessive. We recognize that equity awards dilute existing shareholders, and, therefore, we are mindful to responsibly manage the growth of our equity compensation program. We believe our historic three-year burn rate is reasonable, and we are committed to effectively monitoring our equity compensation share reserve and burn rate to ensure that we maximize shareholders' value by granting the appropriate number of equity awards necessary to attract, reward, and retain employees, directors and consultants. ISS itself measures equity spend through its "burn rate" metric and has established a benchmark of 2.84% for three-year historical responsible equity spend. Using ISS's methodology, our three-year average adjusted burn rate (which incorporates a volatility multiplier of 1.5 for full value awards) was 0.96% and our three-year average unadjusted burn rate was 0.64%, each well below the ISS benchmark.

In response to ISS's adverse recommendation on Proposal No. 4 and to increase the likelihood that our shareholders will vote in favor of and approve the plan, our Board of Directors approved an amendment to the plan to reduce the number of shares of our common stock reserved for issuance under the plan by 1,400,000 shares, from 5,000,000 shares to 3,600,000 shares. Accordingly, subject to adjustment as provided in the plan, the maximum number of shares of our common stock to be authorized for issuance under the plan, as amended, is 3,600,000 shares. Correspondingly, the limit on shares of common stock that may be awarded as Restricted Awards (as defined in the plan) under the plan was also reduced from 5,000,000 shares to 3,600,000 shares. The overall share reserve reduction reduces the potential dilutive impact of the plan and the overall cost of the plan. The Board of Directors made no other changes to the plan. A copy of the plan, as so amended, is attached to these additional proxy materials as Appendix A and replaces the copy of the plan attached as Appendix A to our definitive proxy statement.

Reasons Why You Should Vote in Favor of the Plan Amendment

The Board recommends a vote "FOR" approval of the amendment of the plan because the Board believes the proposed amendment is in the best interests of the Company and our shareholders for the following reasons:

• Allows us to attract and retain talent. Talented, motivated, and effective employees, non-employee directors and consultants are essential to executing our business strategies. Stock-based compensation has been an important component of total compensation for our executive officers and key employees for many years because such compensation enables us to effectively recruit and retain qualified individuals while encouraging them to think and act like owners of the Company. If our shareholders approve the proposed amendment, we believe the additional shares will allow us to maintain our ability to offer competitive compensation packages to both attract new talent and retain our best performers.
• Consistent with our pay-for-performance compensation philosophy to increase shareholder value. Over time, the most significant component of total compensation for our executives is incentive compensation in the form of both stock-basedand cash-basedincentives that are tied to the

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achievement of business results. We use incentive compensation both to reinforce desired business results for our key employees and to motivate them to achieve those results. Adding shares to the plan is consistent with our compensation philosophy and will enable us to continue to use stock- based incentives as part of our executive compensation strategy.

• Aligns director, employee and shareholder interests. We currently provide long-termincentives primarily in the form of restricted stock unit awards to our non-employeedirectors, executives, and certain key employees. We believe our stock-basedcompensation programs, along with our stock ownership and retention guidelines, help align the interests of our non-employeedirectors and employees with those of our shareholders. We believe our long-term stock-basedincentives help promote long-termretention of our employees and encourage significant ownership of our common stock. If the plan amendment is approved, we will be better able to maintain these important means of aligning the interests of our non-employeedirectors and employees with those of our shareholders.

How to Vote or Change Your Vote

Given public health concerns related to the ongoing coronavirus pandemic (COVID-19), we are holding our Annual Meeting virtually again this year. You or your proxyholder will be able to attend the 2021 Annual Meeting online, vote and submit questions by visiting www.virtualshareholdermeeting.com/THO2021 and using the 16-digit control number included on your notice card, on your proxy card or in the voting instructions that accompanied your proxy materials. You will be able to vote your shares electronically during the Annual Meeting by following the instructions available on the meeting website. We encourage you to vote your shares prior to the Annual Meeting

In accordance with the rules of the Securities and Exchange Commission (the "SEC"), instead of mailing a printed copy of our proxy materials to each shareholder of record, we may furnish our proxy materials, including this Proxy Statement and our Annual Report to Shareholders, by providing access to these documents on the Internet. Generally, shareholders will not receive printed copies of the proxy materials unless they request them.

If your Common Stock is held through a broker, bank, or other nominee (held in "street name"), you will receive instructions from the entity holding your stock that you must follow in order to have your shares voted. If you want to vote your shares at the Meeting, you must obtain a legal proxy from the entity holding your shares and submit a ballot virtually at the Meeting.

If you hold shares in your own name as a holder of record with our transfer agent, Computershare, you may instruct the proxies how to vote by following the instructions listed on the Notice of Internet Availability ("Notice Card") or the proxy card (if printed materials were requested).

Shareholders may vote their shares in any of the following ways:

• By Internet: You may vote by internet 24 hours a day through 11:59 p.m., Eastern Standard Time, December 16, 2021, by following the instructions listed on the Notice Card.
• By Telephone: You may vote by telephone 24 hours a day through 11:59 p.m., Eastern Standard Time, December 16, 2021, by following the instructions listed on the Notice Card.
• By Mail: You may vote by mail only if you request and receive a paper copy of the proxy materials and proxy card. You may request proxy materials by following the instructions listed on the Notice Card. You may then vote by completing, signing, dating, and returning a proxy card.
• Virtually: You may attend the Meeting virtually
  at www.virtualshareholdermeeting.com/THO2021 and enter the 16-digit control number included in your Notice of Internet Availability of Proxy Materials, on your proxy card, or on the instructions that accompanied your proxy materials. You will be able to vote your shares electronically during the Annual Meeting by following the instructions available on the meeting website.

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A proxy submitted by mail that is properly executed and timely returned to our Company that is not revoked prior to the Annual Meeting will be voted in accordance with your instructions. If no instructions are given with respect to the proposal to be voted upon at the Annual Meeting, proxies will be voted in accordance with the recommendations of our Board of Directors on such proposals. You may revoke your proxy at any time until exercised by giving written notice to the Secretary of our Company, by submitting a ballot virtually at the Annual Meeting, or by timely submitting a later-dated proxy by mail, internet, or telephone. At our Annual Meeting, a representative of Broadridge Financial Solutions, Inc. will tabulate the votes and act as the inspector of election.

If you hold shares in your own name as a holder of record with our transfer agent, Computershare, have voted on Proposal 4 and would like to revoke your proxy and change your vote, you can do so:

• By Internet: by voting again by internet 24 hours a day through 11:59 p.m., Eastern Standard Time, December 16, 2021, by following the instructions listed on the Notice Card;
• By Telephone: by voting again by telephone 24 hours a day through 11:59 p.m., Eastern Standard Time, December 16, 2021, by following the instructions listed on the Notice Card;
• By Mail: If you have received a paper copy of the proxy card, by properly completing, signing, dating, and returning another proxy card with a later date indicating your vote on Proposal 4 and returning it to us prior to the Annual Meeting;
• Virtually: You may attend the Annual Meeting virtually as described above and re-cast your vote by following the instructions for voting available on the meeting website; or
• By Written Revocation: by sending a written document revoking your earlier proxy (which must be received prior to the vote on Proposal 4 at the Annual Meeting) to our Corporate Secretary at 601 East Beardsley Avenue, Elkhart, Indiana 46514 and voting by one of the methods described herein;

provided, however, that if your shares are held in street name by a broker or other nominee, you must contact your broker or such other nominee to revoke your prior proxy and change your vote on Proposal 4.

Only shareholders of record at the close of business on October 18, 2021 or their proxy holders may vote at our Annual Meeting.

Board Recommendation

Our Board of Directors recommends that you vote FOR the approval of the amendment to the Plan described in Proposal 4 as amended and supplemented hereby.

Our definitive proxy statement, including these additional proxy materials and our Annual Report on Form 10-K for the fiscal year ended July 31, 2021, as filed with the Securities and Exchange Commission, are available free of charge at www.proxyvote.comor www.thorindustries.com.

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