Follow these safety tips to protect against CO poisoning: Never use a generator indoors, including in homes, garages, basements, crawl spaces, and other enclosed or partially-enclosed areas, even with ventilation. Opening doors and windows or using fans will not prevent CO build-up in the home. Follow the instructions that come with your generator. Locate the unit outdoors and away from doors, windows, and vents that could allow CO to come indoors. Install battery-operated CO alarms or plug-in CO alarms with battery back-up in your home, according to the manufacturer’s installation instructions. The CO alarms should be certified to the requirements of the latest safety standards for CO alarms (UL 2034, IAS 6-96, or CSA 6.19.01). Test your CO alarms frequently and replace dead batteries.
Your real estate agent can give you a ballpark figure by showing you comparable listings. If you are working with a realtor, they may have access to comparable sales maintained on a database.