Been perusing the list for some time -- thanks to everyone for so much helpful information!
I am preparing to build a replica of a Forest Service lookout as no-utilities guest cabin/getaway/office on my property. The D-6 cupola model is a 12x12' hipped roof style (you can see pictures if you search for "D-6 cupola" on Google images search). Due to likely code constraints, I have given up on the idea of actually putting it on a tower.
That said, I live on the side of a very small extinct volcano, and portions of my property are covered with car-sized basalt boulders. Can anyone think of a reason why I couldn't just use a group of these as foundation piers and post-up from them to the primary beams?
I should probably drill into the boulder with a rock drill and build up from those Simpson saddle brackets that one finds on the pierblocks. That way the entire thing won't slide off the rocks during the next earthquake.
Advice? Concerns? Laughter and fingerpointing?
Like the Shadow Mountain one here?
http://www.qsl.net/w7xaq/lookouts.htm
It's gorgeous.
Afraid I can't help.
My concern with building on more than one boulder would be the possibility that one or more of them might slowly creep downhill, tearing the beams from the brackets. I think you'd have to somehow tie the boulders together in such a way that they won't move, or if they do, they all move together.
Bart
Sounds good to me-- at the worst you may need to check with an engineer and get his stamp of approval to address any concerns the building department may have, if they are involved. :)
I agree. Assuming the boulders are well anchored in place they should make a very solid footing. You can epoxy the brackets into drilled holes and hold up just about anything. Many very old buildings just used mortared (or even dry stacked) stone foundations off of buried stone.
Everbody who analyzes every building they go into to see how its built -raise your hands---:D
I have looked at the buildings in the California gold country for years. Many used stone -rocks- boulders etc. A museum I checked out used flat slate stacked approximately 18 feet high and it appears to have used clay for mortar. The whole building was then plastered over and is still in use.
The Chew Kee store in Fiddletown was built of rammed earth and was restored a few years back. Many of these buildings were built from 1849 to 1860. Many are still standing. They expected to find a rock foundation during restoration, but the Chew Kee store used no rock foundation. Only rammed earth. The main damage to the walls was at the contact line where the walls met the ground where leaves and snow collected. That is rather interesting- I just read a few weeks ago that the acids from the Oak trees taken down through the soil by rain is part of what decomposes rocks into clay.