Sealing Gas Water Heater Closet
When you are sealing a home it is critical to know about your gas appliances. If they are in the home area like a closet then the doors should be sealed and outside air brought in from the attic.
You should always install a CO detector. Carbon monoxide is a toxic gas, that is colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect. At 100ppm there is danger to human health.
Please have a professional seal this for you.