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papakevin 09-14-2012 02:58 PM

Block foundation under cabin
2 Attachment(s)
We are having a contractor install a block foundation under an existing cabin which was previously on steel stilts. The steel was badly rusted and needed to go.

The contractor dug a trench, poured some concrete and will start building up the block foundation underneath the cabin (which they raised up) soon.

My question - how deep and wide should concrete be in order to place blocks on top of it? I'm traveling out of town on business, but have received a couple photos of the job in process. To me, the depth seems too shallow. (See attached photos). The property is in Southern Indiana, just North of Louisville, KY.


nealtw 09-14-2012 05:10 PM

The trench should be below frost level in your area. The concrete should be about 8" deep, give or take a little and the width depends on soil condition and the weight of the house. Our smallest footing would be 18" x 8" and 2 rebars 5/8" diameter placed 2" from the bottom of the footing.

papakevin 09-15-2012 03:47 PM

4 Attachment(s)
Stopped by the property today and they have made a lot of progress, so I guess it's no longer a concern....

Assuming they should jack up the house to fit in the new top plates before it is lowered down, right?

papakevin 09-15-2012 03:49 PM

Follow up question - should I spray or coat the block with something before the dirt gets back filled?

BridgeMan 09-15-2012 10:17 PM

Nice looking block work, but I think the footings are too shallow for your climate. My map shows Indiana frost lines ranging from 15" to 25", meaning there's a chance there will be some heaving in the building's future. Maybe enough compacted fill placed up against the walls will get you close to that.

And yes, you should seal the block with an asphaltic mastic, to keep from turning the crawl space into a swamp. And it wouldn't hurt a bit to extend the downspouts at least 5' away from the walls, instead of dumping the roof run-off right next to the walls like it is now.

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