X0306 4 2021-03-05 0 0001650729 SiteOne Landscape Supply, Inc. SITE 0001776771 Weller Greg MANSELL OVERLOOK 300 COLONIAL CENTER PARKWAY, SUITE 600 ROSWELL GA 30076 0 1 0 0 EVP of Operations Common Stock 2021-03-05 4 M 0 2000 8.02 A 12303 D Common Stock 2021-03-05 4 S 0 2000 155.21 D 10303 D Common Stock 2021-03-05 4 M 0 865 38.73 A 11168 D Common Stock 2021-03-05 4 S 0 865 155.85 D 10303 D Common Stock 2021-03-05 4 M 0 1000 77.04 A 11303 D Common Stock 2021-03-05 4 S 0 1000 155.61 D 10303 D Stock Options (right to buy) 8.02 2021-03-05 4 M 0 2000 0.00 D 2025-04-15 Common Stock 2000 7294 D Stock Options (right to buy) 38.73 2021-03-05 4 M 0 865 0.00 D 2027-02-17 Common Stock 865 3000 D Stock Options (right to buy) 77.04 2021-03-05 4 M 0 1000 0.00 D 2028-02-14 Common Stock 1000 7750 D The price reported in column 4 is a weighted average price. The shares were sold at prices ranging from $155.64 to $155.90, inclusive. Upon request by the SEC staff, the issuer, or any security holder of the issuer, full information regarding the number of shares purchased or sold at each separate price will be provided. The price reported in column 4 is a weighted average price. The shares were sold at prices ranging from $155.58 to $155.72, inclusive. Upon request by the SEC staff, the issuer, or any security holder of the issuer, full information regarding the number of shares purchased or sold at each separate price will be provided. 46,472 options were granted on April 15, 2015, and vest and become exercisable ratably in five installments on each anniversary of April 15, 2015, subject to the Reporting Person's continued employment. Prior to the transactions reported on this Form 4, 9,294 of these options that remain outstanding had vested. 8,365 options were granted on February 17, 2017, and vest and become exercisable ratably in four installments on each anniversary of February 17, 2017, subject to the Reporting Person's continued employment. Prior to the transactions reported on this Form 4, 3,865 of these options that remain outstanding had vested. 8,750 options were granted on February 14, 2018, and vest and become exercisable ratably in four installments on each anniversary of February 14, 2018, subject to the Reporting Person's continued employment. Prior to the transactions reported on this Form 4, 6,562 of these options that remain outstanding had vested. /s/ Briley Brisendine, Attorney-in-fact for Greg Weller 2021-03-09