The “Call Me By Your Name” actor, 34, also revealed he’s been working in construction.
"This one of my best friends, Ashton," Hammer said as he introduced his friend Ashton Ramsey.
He continued: "For the last 2 months or so I have lived with Ashton, worked construction with Ashton, and hiked with Ashton every day."
“He has been such a good friend (and boss) and has been the most supportive friend anyone could ever ask for," the “Social Network” star said.
Hammer concluded: "Today might be my birthday, but I just wanna say thank you to @ashtonramsey and say I love you dude."
In July, Hammer and Chambers, 38, revealed they were splitting up after 10 years of marriage.
“Thirteen years as best friends, soulmates, partners and then parents. It has been an incredible journey, but together, we’ve decided to turn the page and move on from our marriage," the two said in a joint statement.
They continued: "As we enter into this next chapter, our children and relationship as co-parents and dear friends will remain our priority. We understand this news lends itself to public dialogue, but in the interest of our children and our family, we’re asking for privacy, compassion and love during this time."
Hammer and “The Game Plan” actress share two children: Harper, 5, and Ford, 3.
Despite their split, the exes seem to remain on good terms, with Chambers sharing a family photo for Hammer’s birthday. “You are loved,” she said in a brief Instagram Story post.