I'd strongly avoid commercial construction unless you have a background in it. You've got so many issues: scope of work changes, payment delays, scheduling with other trades, etc. I've looked at many home services and talked to people who work with GCs; it's very, very difficult. You'll get trapped in a rat wheel of taking a big project, then doing whatever you can get paid because you need that check. The GC know this and will take advantage of you. That's the construction game - most GCs are good because they manipulate their subs (that's you). Maybe you find the few good ones or this business has relationships with property managers for plumbing retrofits. The latter is a solid biz with good job sizes, but still has project risk and long payment cycles. I'd be very wary of working with GCs on new commercial. And Don't assume you can just change the mix - B2C and B2B are two different businesses. Second Henry's comment.

I’ve owned and consulted for a few trade businesses. Commercial could be an asset depending on what type of commercial work they do. In my experience, a blend of commercial and residential could work well. Theirs just not enough information here to know.