Second, gas piping should not be leaking, and if it is, you should smell the gas leak and repair it immediately. If you are concerned that the exhaust fan flapper that should close to prevent back-drafts of outdoor air into the building could malfunction and admit leaking gas from an LP...
If there's no operable window, be sure to install an exhaust fan to keep the space fresh. You'll also want to make sure that there's enough space for a hanging cabinet above the toilet tank to house commonly needed supplies and that there's room for a small wastebasket on the floor....
1. Have the range hood exhaust fan system inspected: is it dirty with grease? If so it needs to be cleaned in any event, for fire safety? Is it dirty with mold: cleaning would make sense. 2. What's the cost of cleaning the existing system? 3. What's the cost of replacing the...