James C. Pelletier - 15 May 2024 Form 4 Insider Report for MASONITE INTERNATIONAL CORP

Footnote F1

Each Masonite International Corporation (Masonite) performance-based restricted stock unit represents a contingent right to receive one common share of Masonite (the Shares). Represents performance-based restricted stock units granted on February 23, 2022, August 8, 2022 and February 27, 2023, in each case vesting based on the achievement of certain pre-established performance metrics. The number of Shares subject to these restricted stock units in the table reflects the deemed level of achievement of applicable performance goals as described in footnote 4 below.

Footnote F2

Represents Shares disposed pursuant to the Arrangement Agreement, dated as of February 8, 2024 (the Arrangement Agreement), among Masonite, Owens Corning, and MT Acquisition Co ULC (Purchaser). Pursuant to the Arrangement Agreement, on May 15, 2024 (Effective Time), by way of a statutory, court-approved plan of arrangement (the Arrangement) under Division 5 of Part 9 of the Business Corporations Act (British Columbia), Purchaser acquired all of the Shares of Masonite for $133.00 per share in cash (the Arrangement Consideration).

Footnote F3

Pursuant to the Arrangement Agreement, at the Effective Time, each award of Masonite restricted stock units (whether time- or performance-based) held by the Reporting Person was converted into an award of Owens Corning time-based restricted stock units with respect to Owens Corning common stock (OC Award) of equivalent value and with the same terms and conditions as applied to such stock units immediately prior to the Effective Time.

Footnote F4

(contd from footnote 3) The number of shares of Owens Corning common stock subject to each such OC Award equals the number of Shares subject to the corresponding Masonite restricted stock units immediately prior to the Effective Time multiplied by an exchange ratio of 0.76424, which equals the quotient obtained by dividing (i) the Arrangement Consideration by (ii) the volume-weighted average closing price per share of Owens Corning common stock on the New York Stock Exchange for the ten consecutive trading day period ending on the date that is two trading days prior to the Effective Time, provided that, in the case of any Masonite restricted stock unit subject to performance periods that were incomplete as of the Effective Time, such performance goals were deemed satisfied at 122% of the target level (or deemed achieved in full if such award does not have a target performance construct) at the Effective Time.