Originally Posted by hikingdad
I would be cautious about drilling/hammering into your houses foundation
Been in construction for 20 years and have had to attach all manner of materials to masonry walls....finished basements, added structural components, remodeling etc. Work for a masonry materials manufacturer now....as long as there is no history of unstable walls, excessive cracking, water infiltration, soil erosion, etc, dropping a couple of screws into a concrete block should cause no harm....although YMMV.
To hang a third hammock in my basement workshop this weekend I needed an anchor on a wall. Ran an eye-bolt through a 10" x 5" x 3" piece of lumber with a counter sink on the nut end. Then fastened the board to my concrete foundation with four 3" nails shot with a .22 gauge nailer. Works great!