How long is a person with covid contagious for? i dont have it i just live in a house with someone who does. how would i make it so i dont get it? thank you?

Your question has academic answers and clinical answers. Someone who is vaccinated can become less contagious, but that would be much different if the person had immune-suppressing medications. In general, we are more contagious before showing symptoms and in general, people become less contagious after 5 days, Although, some symptoms and/or physical examination findings trump those issues.

The COVID-19 is contagious10 days after onset of symptoms. Up til then, if you haven't been vaccinated, ideally you should live someplace else. If that's not possible, avoid all physical contact with that person, and both you and s/he should wear masks pretty much all the time except when eating. Don't sleep in the same room, and for sure not the same bed. Get vaccinated and boosted.

Visit this site for a detailed and authoritative answer: https://www.cdc.gov/coronavirus/2019-ncov/your-health/quarantine-isolation.html#:~:text=Get%20tested%203%2D5,do%20not%20have%20symptoms.