How can I fix a moldy wall and ceiling?

You can buy a mold killer spray at many home building/hardware stores. I'd start by giving everything a good dose of that. Running a dehumidifier/fan in the area might help too. Wear a mask, when you get to tackling the project and tear back anything that shows any sign of mold.

hire a crew to come in and evaluate the situation. get at least 3 bids. mold takes a certain amount of care in removing it.. bleach wont kill the mold spores, if you are lucky, your home owners insurance may help.

Call in a mold remediation team, heavily regulated by the EPA. Don't mess with it yourself as you can unknowingly spread to other parts of your home. Bleach is useless when it comes to mold, it doesn't kill the mold spores.

https://www.servicemaster-restoration-cleaning.com/2017/03/mold-myths/

There are several ways to get rid of mold, but most importantly, you need to address the root cause to keep it from returning. This article focuses on the bathroom, but is an overall great article that covers methods of how to remove mold, if bleach is safe to use, and how to prevent it from coming back. Hope this helps! Hugs, Holly

https://pinkfortitude.com/mold-in-the-shower/

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Sounds like you've got water issues, maybe a roof leak or a pipe leak. Mold exposure is very serious, I was exposed on the job and suffered for about 5 years until I found out they knew about the problem and 8 other employees had quit due to illness related to the mold.

Your homeowners insurance should cover the cost of the remediation. Get someone to do the inspection first to find where the water is coming from by inspecting the attic, Then when they remove all the drywall, any leaks should have left water trails on the studs or ceiling joists. If there is a bathroom above have it inspected.