DIY foundation options for bedrock

Started by jbd, February 06, 2015, 10:24:41 PM

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jbd

Hi, new member here.  I'm planning on building a ~10x16 cabin (beds only) in an area with exposed rock outcroppings (ie. bedrock) and very little topsoil.  I'm at a loss about how to build the foundation.

I'm going to experiment with an earthen floor, so pier and beam is out of the question.  All I found during some initial research was a method to trace and cut the contour of the bedrock on plywood sheets, which would then be used as formwork for a concrete stemwall.  Not only does that sound like a ton of work, but I'm doing this myself so I'd probably have to have a concrete truck deliver the concrete to have a chance at getting a monolithic pour.

I'd much rather make a 2 concrete block-high stemwall if possible, but how can I make everything level?  Will I need to import a bunch of soil and then level and compact it?  Are there any good books or websites explaining the process?

Thanks for any suggestions.

flyingvan

Been there, done that....Unfortunately some of the pics have corrupted but you'll get the idea http://countryplans.com/smf/index.php?topic=11812.msg151774#msg151774
Basically you trench where ther is soil, and drill in the bedrock where there isn't.  You suspend 2x material over the layout then sling fabric and hang rebar.   I've used it twice so far.  You have to make really sure the rock is suitable to hold a house---I had to have a geologist certify my rock
Find what you love and let it kill you.


jbd

Thank you, that looks like a good system.  Nice job on the formwork.  I bet it took forever to get that all perfectly level.  I will probably have to hire a concrete truck and crew like you did.

flyingvan

The crew were all friends, it was the only day of help I really needed.  Getting it level was pretty easy---I just adjusted the height of the yokes as needed.  I usually make my own concrete but didn't want any cold joints in the foundation.  The first one was 20X30 with a stemwall in the middle and took 3 concrete trucks and a pumper (I ordered way to much and we used most of the third truck to extend the boat ramp at the lake) The second one was 20x20 and only took one truck
Find what you love and let it kill you.

jbd

Ah, that helps get an idea of how much concrete I'll need.  Thanks!


cabin fever

Unless this is for a vehicle, you could get away with piers.  10" sono tubes, spaced 4-5 feet, 1" dowels glued a foot into bedrock, each pier.  That would do it.