WOW! What a broad question.
Basements are damp because of water or moisture making its way into the basement. It's that simple. HOWEVER, the 'fix' that's needed to keep the water and moisture out of the basement is another matter.
If you have a 'specific problem/question', and want to share it w/us for advice, we'd be glad to help. I can't imagine that you're just curious as to why a basement it damp.
Jay J -Moderator
PS: If you have a question, PLEASE give some background about the problem ...
- 15 Old House Features We Shouldn't Abandon
- 13 Lazy Cleaning Tricks for a Spotless Home
- Laundry Room Ideas to Knock Your Socks Off
- Insanely Easy 60-Minute Home Improvements
- 12 Sheds You Could Live (or Work) In
- Assembly Required: 15 DIY Kit Homes
- 7 House Sounds You Never Want to Ignore
- 10 Surprisingly Simple Woodworking Projects
- Worth It: 8 Renovations That Pay You Back
- Organize Your Life with 12 Dollar-Store Buys
- 9 Totally Amazing Mobile Home Makeovers
- Don't Make These 7 Mistakes in Small Spaces
- 16 Sneaky Storage Ideas
- 15 Totally Unexpected DIY Flooring Alternatives
- 7 Easy Budget-Friendly Backyard Makeovers
- 10 Closet Cures That Cost Less Than $100
- 11 Easy DIY Projects to Declutter Your Home
- 10 "Zero Dollar" Garden Hacks
- 10 Killproof Plants for a No-Effort Landscape
- 9 Insanely Easy 1-Hour Backyard Projects