About 16 months ago I had a 16 x 30 addition put onto the house. We put a basement beneath that area. The rest of my existing house has no basement. Anyway, the basement has a very strong, peculiar odor in it. Everything was properly waterproofed, no high water table, no water issues at all! I do run a dehumidifier becuase without it, it will get humid down there, but that's normal. We have no pets and the smell is not musty or mildewy. In fact I cant really describe it, but it's so strong, I can't leave the basement door open, and everything we put down there gets the smell on it. A few people I have had over tell me it's the concrete itself, but it's been well over a year now since it was poured, and to me, it doesn't really smell like freshly poured concrete. Some other info.- It is a very confined space- 16 x 30 and three of the walls are 10 inches thick, and the butress wall (the one next to my existing house) is 12 inches thick. I drylocked the floor just to seal it, and used Zinsser Watertite(masonry waterproofer) on two of the walls. The other two are unsealed on the inside. I have two small windows down there. I keep them closed most of the time, but they have been opened, door left opened, and multiple fans running on high to try to purge the smell. I can't get rid of it! Please help!