Loading…
16
Vent: Had a huge rock right where a post needed to go on a job in Boulder.
Instead of moving it, we drilled a pilot hole straight down the middle of the rock and set the post in concrete around it. Saved us half a day of digging. Anyone else ever anchor a post into bedrock like that?
5 comments
Log in to join the discussion
Log In5 Comments
ryan_black5mo ago
Check with the city on that. Boulder has weird rules about messing with natural rock features.
7
quinn6065mo ago
I remember someone moving a few rocks in Chautauqua and nothing happened, ryan_black.
2
richarddixon4mo ago
My buddy tried this outside of Lyons a few years back on a job near the St. Vrain River. He drilled into this big granite boulder, set the post with concrete, and everything looked solid. Then about eight months later, the freeze-thaw cycle cracked the rock right down the middle and the post shifted about four inches. He had to rip the whole thing out and start over with a digger. I guess it really depends on the kind of rock and how deep the water can get in the cracks around it. That Boulder sandstone might be more forgiving than granite in that way.
3
abby_martinez4mo ago
I actually read a thread on a local builders forum last month where a guy in Golden did the same thing. He drilled into a sandstone slab and poured concrete around a fence post, and it held up fine for years with no movement. The trick was making sure the concrete went deep enough around the rock so frost heave wouldn't push the post out. I guess the key is really knowing what type of rock you're dealing with, because some will crack and split over time if the concrete expands differently. Did you have any issues with the concrete bonding to the rock surface?
1