How do decide between build or buy in your private life?

I usually look at how many hours I have to work to earn the money(+tax) to buy a thing or service.

It's almost always cheaper to do it myself, if I can, or can learn within a short time.

For some things (like laying torch down roof), it takes more skill and practice and are relatively high-stakes, I consider that factor against it.

But for some thing (like building a wall), the price of work are orders of magnitude higher than doing it yourself, and the result is going to be the same..

So I'm always kind of considering "How many days do I need to sit in the office to pay it" versus "How many do I need to work.."

For simple things, like changing a window in my house, it's obvious.. It takes 2 or 3 hours to do myself, but I'd pay someone 2-3 DAYS worth of my salary to do it for me...

I end up doing a lot of stuff myself..

What's your considerations and decision process like when you decide whether to build or buy stuff ?