Chief Executive Officer Authorized Signatory (Translation) — 1 — Enclosure 1 Summary of Adjustment of the Exercise Ratio by adjusting Number of ORI-W1 Reference is made to the issuance of 406,573,990

Chief Executive Officer Authorized Signatory (Translation) — 1 — Enclosure 1 The amended contents are written and underlined in blue. Summary of Adjustment of the Exercise Ratio by adjusting Number of ORI

Wongsinudom Chairman and Independent Director - - - 1,200,0501/ 0.18 2. Mr. Kitti Jivacate Director 1 0.00 Director and Chief Executive Officer 372,858,9632/ 55.85 3. Miss Nilrat Jarumanopas Director 1 0.00

Sudbuntad) Chief Executive Officer - 1 - DIAMOND BUILDING PRODUCTS PUBLIC COMPANY LIMITED AND ITS SUBSIDIARY MANAGEMENT DISCUSSION AND ANALYSIS (For the Consolidated Financial Statements of the 3rd Quarter

assets of the Company. Please be informed accordingly. Respectfully yours, -Weera Louwitawas- (Mr.Weera Louwitawas) Chief Executive Officer 1 Information Memorandum Regarding the Acquisition of Assets of

accordingly. Yours sincerely, - Signed – (Mr. Sorapoj Techakraisri) Chief Executive Officer - 1 - Enclosure Information Memorandum regarding the Acquisition and Disposition of Pace Development Corporation

accordingly. Yours faithfully, For and on behalf of Diamond Building Products Public Company Limited (Mr. Satid Sudbuntad) Chief Executive Officer - 1 - DIAMOND BUILDING PRODUCTS PUBLIC COMPANY LIMITED AND ITS

Analysis (MD&A) as attached herewith. Please be informed accordingly. Yours faithfully, For and on behalf of Diamond Building Products Public Company Limited (Mr. Satid Sudbuntad) Chief Executive Officer - 1

Sudbuntad) Chief Executive Officer - 1 - DIAMOND BUILDING PRODUCTS PUBLIC COMPANY LIMITED AND ITS SUBSIDIARY MANAGEMENT DISCUSSION AND ANALYSIS (For the Consolidated Financial Statements of the 2nd Quarter

against COVID-19 and hope for the globe to pass through this difficult time. ………………………………………………………. Tamonwan Narintavanich (Chief Financial Officer) 1 Asian Development Bank