Decaying foundation: garage corner

Old 10-02-15, 07:42 AM
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Join Date: Sep 2008
Location: New Jersey
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Decaying foundation: garage corner

The corner of my garage foundation(Traditional Split Level) has "crumbled". Its a block foundation with a external concrete/mortar trowled covering. The garage is a poured slab with nothing below and bedrooms above. The corner has a downspout right on the corner that has crumbled. I'm assuming(over many years) water/ice damage has caused the cement covering and block material to crumble. I can reach in to the block foundation hole and it drops about 18" (finger to elbow length) and is 5" x 5" (eg. post hole size ??). I think the size of a normal opening in a cinder block.
Q. To repair (after through cleaning) Should I backfill the hole using stones or gravel to the surface and then patch the above ground area with a quick setting cement (e.g QUIKRETE Quick Setting) and then trowel finish the exterior surface OR should I back fill the hole (18 ") with concrete to the surface and then finish the repair by patching (plugging) the corner of the foundation to align with the rest of the foundation and then smooth skim the surface with quik crete setting concrete.

Your advice will be welcomed and appreciated.

Oldman1 - getting old and too tired of home repairs
Old 10-02-15, 09:11 AM
Join Date: May 2015
Location: USA
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A picture would be helpful, but if I follow your description I would avoid just filling the void with gravel because that is just going to allow water to enter the block assembly where it will continue to deteriorate additional block.

I had a similar situation with a stem wall supporting the landing for my entrance door. I dug down enough to expose all the damaged block and then removed the front half of the damaged blocks using a variety of tools (mostly swearing). Then I mortared in solid half blocks, and then parged and damproofed the whole area.

Your concrete idea may work, but it'd be better if you exposed the area to see if the damage extends further. You don't want to repair only part of the damage leading to another repair in near future. You may also find the concrete just disappears into the block voids.

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