I am selling a house and the buyers are requiring that I install fire wall/blocking at furnance closets and water heater closets. What are they and how would I install them.

Thanks

Usually 2 layers of 5/8 inch fire code drywall are attached to the ceiling . All ceiling penetrations must be skirted by metal because usually you cannot cut the drywall that close. We also use a fire proof approved caulk on some small application cracks.(Hilte) or other brand.

Watch out for any penetrations that are used for combustion air. In this area the must be extended down two the floor area. They can act as a chimney during a fire.
A trick used her is to use a non closeable register and cut it into the supply air plenum. This takes care of the combustion air problem. You might want to check with your local building department also for advice.

You will find out this will be a real pain in the butt job.