construction question

johnwayne360 · Jun 12, 2012

How close can you dig next to a building before you run into trouble with foundation? I want to make a feeding area next to an old hog floor. Problem is there is a machine shed 20 feet away and 5 feet higher, and I need to take about an extra 10 feet for a feeding lane, leaving 10 feet of dirt to the back of the shed. I will be below footing level when i get done digging. Will a retaining wall be needed?

ohiojim · Jun 12, 2012

everything is dependent on your type of soil, sand and gravel will give you fits,....clay will hold up till ya get done,..kinda judgement call

Billy NY · Jun 12, 2012

Load imposed on the machine shed footing is displaced at a 45 deg angle, so every 2 feet you drop 1 foot if I am correct. Some of the basics regarding adjacent footings at different elevations and in close proximity call for the existing foundation to be underpinned to the same depth as the proposed or new footing elevation adjacent. Depending on the material in that 10'-0" span, thats what retains the undisturbed material under the footing.

If this is a feed lot, won't you be in there with loader or something ?, the edge of that earthen slope could be compromised, eroded, etc. Seems like a sharp angle of repose. A retaining wall would back up the existing fill if you need that area to remain as is, or you could underpin, the wall would be easier, but keep in mind the existing footing displacing a load outward at a 45 deg angle could perhaps transfer to a retaining wall, so that would be best done right, tied back or whatever works best to make sure it takes whatever could be imposed on it.

Sounds a bit close, good idea to be careful about considering a design.

Adirondack case guy · Jun 12, 2012

A 45 degree slope is 2'down--2' out, or 12 on 12 pitch. That is feasable in clay conditions. Sandy or gravel soils will require much less "slope" I would cover the sloped area with Geotech Fabric and cover the fabric with riprap, if it is clay soil. Gravle or sand may require further measures such as a retaining wall. Anual rainfall will also affect the integrity of the area. That is the reason for fabric and riprap.

dpendzic · Jun 12, 2012

the angle of repose of a typical sand and gravel soil is around 30 degrees--if you are 10 ft away you could go down around 5 ft below the shed floor.
If you park heavy equipment on the floor then that is called a surcharge and you shouldn't go down as much.
Clay soils have a steeper angle of repose when dry but they loose their strength when wet and tend to slid slowly over time.

Billy NY · Jun 13, 2012

Right, I was referring to the 10'-0" area from the machine shed, to the beginning of the proposed feed lot, whereas the elevation difference is 5 feet according to what he describes.

I would agree on fabric and or similar if no wall is to be constructed, but this could be a maintenance or remedial work later on, would seem best to figure on a wall or other means to retain, given the close proximity of the adjacent footings.

That and if he's using a loader in there, a wall would be nice to back up any miscellaneous feed, manure or what have you when cleaning vs the edge of a slope that could wash onto the slab or old hog floor as mentioned.

BTW, very nice photos the other day, good to see photos like that, all fields, woodlots and no darned houses LOL !

construction question

johnwayne360

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ohiojim

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Billy NY

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Adirondack case guy

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dpendzic

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Billy NY

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