We recently purchased a slackline to take on family camping trips. Does anyone have a good do it yourself indoor solution for the winter? How can I tell if the poles in my basement can support a slackline?
There are lots of options for buying indoor slack line setups, or if you're confident in your engineering abilities, you can build one yourself, I would NOT recommend trying to anchor a slack line to anything in your house, unless you are willing to drill holes in the concrete foundation in your basement to make fixed anchors.
DIY Indoor Slackline
Manufactured Indoor Slacklines
If your basement columns are made out of reinforced concrete as I suppose, get a metal stud finder to be sure not to drill the steel and just go for it.
Use a chemical bolt (see here: http://www.fischer.de/en/Home/Product-Range/Product-Selector.aspx/cpage-category/pcategory-1001076852/ for an example) by following its instructions and then happily go for it.
Source: I hung a hammock that very way, and bolted a 'rock climbing' anchor indoor to practice with ropes and knots as well.
Of course this is only true in case you have a concrete basement.