Foundation questions

[shadycrew31]

Doubt many have ran into this issue before, but hoping I can get some advice. We are being required to use the old foundation from the previous garage in addition to the new foundation. I had a concrete wall poured for the larger footprint however the previous garage seems to have skipped any block wall or footer under the garage door All we have is about 9" of concrete under that is just clay soil. So here are my options as I see it, would love any feedback or tips from previous experience.

1. Remove the existing concrete, dig 18 inches of soil add stone, compact it down then add 3 courses of block with mortar.


2. Dig out only the small section of clay throw stone in compact and add block in, then add the final row of block on top of the existing concrete.


3. Add block in without any stone to the small section that was broken up, then add the second course of block continuing over the existing concrete.

Pic of the area in question

Pic of the entire site

 

[Kaizen]

not seeing pics......

 

[larry4406]

In my neck of the woods the garage slabs are typically always structural slabs due poor soils. At the garage door opening, a turn down slab is typically done. This turn down is below the frost line with steel reinforcement that once poured interlocks with the garage door wing walls. Rare for me to encounter a wall or footer for the slab entrance to turn down and bare on.

I agree no pics for me ...

 

[shadycrew31]

Sorry, was trying to host from google photos moved to flickr, let me know if the pics are still missing.

 

[ConCretin]

It looks to me like there is a block foundation under the door but they poured the slab over it? If that's the case, why can't you just do the same?

I assume there is an existing concrete footer under the block. If you need to add or replace block under the door, I'd definitely dig down and start rebuilding from there. If there isn't a footer under the door, you could add one.

The reality is that unless you need a frost barrier under the door, you really don't need a foundation at all. You could just add a thickened edge to the new slab on grade. The wall under the opening isn't carrying any building loads.

 

[shadycrew31]

It looks to me like there is a block foundation under the door but they poured the slab over it? If that's the case, why can't you just do the same?

I assume there is an existing concrete footer under the block. If you need to add or replace block under the door, I'd definitely dig down and start rebuilding from there. If there isn't a footer under the door, you could add one.

The reality is that unless you need a frost barrier under the door, you really don't need a foundation at all. You could just add a thickened edge to the new slab on grade. The wall under the opening isn't carrying any building loads.

There is nothing but clay under the 9" of cement where the previous garage door was which will become the right side wall of the new garage.

This is basically what it will end up needing to look like.

Here's a better breakdown of the issue. Originally my concrete guy and I thought the block continued under the previous garage door but he stopped breaking it up when he saw that it wasn't.

 

[NUTTSGT]

If the rest of it has a block foundation on a footer, I'd want one there also.

Better yet, might be easier to just form it up and pour it all at once. You'll have a small load charge if you get ready-mix delivered, might as well get your money's worth.

Let all dry/cure and be done rather than dry/cure and lay block and wait on block to start building.

 

[shadycrew31]

If the rest of it has a block foundation on a footer, I'd want one there also.

Better yet, might be easier to just form it up and pour it all at once. You'll have a small load charge if you get ready-mix delivered, might as well get your money's worth.

Let all dry/cure and be done rather than dry/cure and lay block and wait on block to start building.

Yeah my concrete guy said it should be ok since its just a 9' section. He suggested stacking stack blocks on top of what concrete is left then add 2 courses of block in the empty area. Now he did a great job with my wall but I'm not keen on the idea of setting some blocks even if its just 9'...