I've read quite a bit and looked over a lot of the building projects here, but I'm still not sure how to approach my foundation. Right now I'm thinking of a roughly 16x16 cabin and I'd like a crawlspace with maybe 30 inches clearance (it's a little high, but I just hate worming around under a house on my stomach because there's no room). I'd like a concrete footer and full block foundation, but the land where I want to put it is very rocky. Trenchers won't work and I have a hard time justifying hiring out a backhoe, which means I'd be digging it by hand. And suddenly the full footer doesn't seem as necessary. I'd rather do posts of concrete blocks since they are cheap and can give me the height I'd like plus be safe from insects. But is this a good idea? How many posts would I be looking at? How deep would my footers need to be?
Quote from: Cropping Up on January 11, 2012, 10:40:27 PM
I've read quite a bit and looked over a lot of the building projects here, but I'm still not sure how to approach my foundation. Right now I'm thinking of a roughly 16x16 cabin and I'd like a crawlspace with maybe 30 inches clearance (it's a little high, but I just hate worming around under a house on my stomach because there's no room). I'd like a concrete footer and full block foundation, but the land where I want to put it is very rocky. Trenchers won't work and I have a hard time justifying hiring out a backhoe, which means I'd be digging it by hand. And suddenly the full footer doesn't seem as necessary. I'd rather do posts of concrete blocks since they are cheap and can give me the height I'd like plus be safe from insects. But is this a good idea? How many posts would I be looking at? How deep would my footers need to be?
I'm not that far from you (West-central Arkansas) and I built a 24'x48' house with a foundation as you're proposing. I built on a very rocky ridge and hand dug the piers 10"dia. x 20" deep and extending 3" above grade. The posts are 6"x6", cut from the red heart of cedar trees and vary from 28" to 34" high. Total of 36 posts on which rest 4 rows of 6"x8"x12' sills cut from yellow pine.
The piers were poured with a vertical 5/8" rebar extending up about 4" and 3" off center. The rebar has a flat plate welded on that has a 1/2" hole in it. I used 1/2" bolts to bolt the posts/rebar/braces (2"x5" yellow pine) together. The lengthwise braces go from the bottom of the posts up to the sills; the widthwise braces are X'ed from the bottom of the posts to the top of the next row of posts. The top of the posts are tied to the sills with angle iron.
Since the crawl space is open, that leaves anything under the house susceptible to freezing.
So I have planned for everything that uses water to be along one of the long walls.
Then I plan on running the water lines (pex) along that wall inside a chase at the baseboard, so that there will only be one short vertical line from ground to house that I will need to protect from freezing.
Best of luck,
Arky
Thanks for the reply, Arky. Have you had any trouble with the wooden sections of your foundation and lower structure? The termites here worry me a lot. They destroyed everything below the flooring of a house addition already on my property and I don't want to same to happen to my cabin when I build. I don't think any of the addition's wood was treated, which I intend to use, but I'm still awfully shy of using wood for anything below the main beams. How did you space your piers? What did you use to block moisture between your piers and beams? Sorry about all the questions. :-[ I just like to know what others have done and how it worked for them.