When do I outsource and when do I hire?

Hi all,

I hope this is on-topic for this sub. If not, I'll post somewhere more appropriate.

I am a director of software development, and I've been working toward building up a team that can sustain at least one major product and ad hoc some in-house custom software.

Everything is working out pretty well, and the business is certainly ramping up. The executives are concerned about hiring more devs, and in Seattle, developers enjoy substantial salaries.

I fully plan on keeping the team cohesive, and potentially hiring contract employees state-side or hiring an outsourcing company to keep velocity high and scale productivity across multiple components of our main product.

I'd like feedback about experiences, even naming names if that's allowed, for outsourcing dev work, what that means when an outsourced team is working on the same / adjacent codebases as the main team.