Are you a licensed contractor? Do you have insurance? You need to be legit to do any kind of work. But don’t do work you’re unqualified to do or you can lose more than the cost of a misbid job. People are sue happy these days.

This is boom time in the trades. Good carpenters are in very high demand. There’s got to be more backstory there.

Back story is I have a wife that is 7 months pregnant. I am a union carpenter and the job i was working on ended so I'm on a temporary layoff but can't afford any time off even if it is temporary so i started like i said a side landscaping "business" to make ends meet. A customer asked me if I could paint his foundation. I painted houses for 3 summers while in high school. I dont have to water seal it he just doesn't like the color the previous owners painted it

You take a picture of the foundation, you ask what color he wants, you go to a good paint store, not a big box..................and you ASK how much do I need for two coats, and the price for the best exterior foundation paint. You gather all, collect $$$ from the client, and collect the rest of the dollars when its done. And pray you remember how to paint, from the high school experience..........and how long it may take you. Your bid is time and materials, and time includes drive, prep, paint, and clean up.

Or you simply say to the client................"You need a painter for that" I landscape"

Just take a good solid guess at how long it's going to take you to do, then add a little bit. You'll get the hang of estimating right away, believe me.

Zinnser WaterTite is good for that. I can't imagine you will need more than a gallon. Make sure you don't paint over dirt. It's probably about a 3-4 hour job for a good painter.

Consider power washing it first.

Okay I am no painter but I sure think it will take more than a gallon since 2 coats will probably be needed for the almost 200 sq ft.

Calculate time and material. Other comment is correct. Paint store will calculate amount of paint/primer.