| have you ever had leaks from your washer any leaks in the roof ???
unusual smells 9 out of 10 times are due to some sort of mold inside the walls. or dead animals, but you have had the smell to long for the latter,that being said you should have someone test for mold, their are so many types of mold out there and with the increase in th ambient temp the smell will get worse, dont ignore it, it can get worse to the point of making family members sick, or worse making the home completely unihabitable. Not trying to scare you but mold and fungus can be very dangerous, i have seen homes torn down because it takes over.
Good Luck |