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Discussion Starter · #1 ·
Hello All,

Description of current crawlspace:

I have a home built in 1912 in Calgary, AB which is sit-in non a crawlspace foundation with no footing. At some point, a portion of the crawlspace has been dug down another approx. 4". Cedar wood walls were installed to hold back the dirt back below the foundation wall (see attached picture). The cedar wall sit approx. 1' from the foundation is some spots.

The reason for my question below is, I have received a quote to lift the house and build a new foundation unit the existing house. I do enjoy completing work myself and saving money so I was thinking if I could complete the majority of the dirt removal myself I could save some labour costs.

My question:
A lot of the dirt in the crawlspace still hasn't been removed. Would it be possible to continue digging out the rest of the crawlspace dirt and using support walls to hold back the dirt? If possible, do you have any recommendations on the best way to approach this?

My thoughts, I would approach this by only digging out 4' sections at a time and installing a wall before continuing to the next section.
 

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retired framer
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The trouble with that is you don't know which shovel full is holding the wall in place.
I would sooner start with a few sections from the outside to make it stable. The trouble with that is working deep in a hole is dangerous too.
 

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ok. then i would figure that they are going to use some kind of excavator to dig out under the house.

which means whatever you did by hand would make no difference.
 

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I would not do it without first talking to the contractor.
It will probably not save you any money.
It is a lot of manual labour.
The lift crew might want the dirt there to raise the house.
 

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Method 1. Do not raise the house; just "lower the basement floor." Excavate at the foundation in three to four foot cross sections as you proposed, you could do one cross section on each of the four sides simultaneously. Underpin, with footing, the four foot section before doing the next four foot section. To give concrete and/or mortar time to set and cure, you could hopscotch about for the next cross section as opposed to put the next cross section next to the previous one.

Method 2. Old foundation to be completely poured new. First prepare the house for jacking (or just suspension in air if not being raised). Demolish the foundation, excavate to the desired depth, repour the foundation with footers, then let the house down onto the new foundation.
 

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Discussion Starter · #14 ·
I would not do it without first talking to the contractor.
It will probably not save you any money.
It is a lot of manual labour.
The lift crew might want the dirt there to raise the house.
Its tight property with not much remove to get equipment on site. the contractor has already told me they will be hand digging the dirt. this is why I was considering starting the work myself.
 

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Discussion Starter · #15 ·
Method 1. Do not raise the house; just "lower the basement floor." Excavate at the foundation in three to four foot cross sections as you proposed, you could do one cross section on each of the four sides simultaneously. Underpin, with footing, the four foot section before doing the next four foot section. To give concrete and/or mortar time to set and cure, you could hopscotch about for the next cross section as opposed to put the next cross section next to the previous one.

Method 2. Old foundation to be completely poured new. First prepare the house for jacking (or just suspension in air if not being raised). Demolish the foundation, excavate to the desired depth, repour the foundation with footers, then let the house down onto the new foundation.
For method 1, the houses in the area seem to be higher up than ours. I know my area is considered a flood zone and is close to a river. Also, the main sewage line sit on the floor of the area that is already dug out. if I go and further down I would need a grinder pump to lift the grey water back to plumb level. This is why I don't think I would consider digging down but would have to consult the city to see if there is any restriction in digging down.

Can you provide any insight into hand digging the dirt and using wood retaining walls to hold back the dirt?
 

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retired framer
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For method 1, the houses in the area seem to be higher up than ours. I know my area is considered a flood zone and is close to a river. Also, the main sewage line sit on the floor of the area that is already dug out. if I go and further down I would need a grinder pump to lift the grey water back to plumb level. This is why I don't think I would consider digging down but would have to consult the city to see if there is any restriction in digging down.

Can you provide any insight into hand digging the dirt and using wood retaining walls to hold back the dirt?
So you are thinking of a finished basement in a flood zone? Would not be anything I would consider?
Will you even get flood insurance?
Does the foundation have footings?
how far would you have to get down if you were just levelling the dirt with the footing?
You do not just dig lower than the footing, you start underpinning 4 ft sections of the footing.
How will you get the dirt out, where will you put it when you get it out?
 

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Discussion Starter · #18 ·
ROI. Don't know. I haven't consulted a private assessment company. that said.

We got the house for a steal of a deal. the property was assessed (by the city) at more than $83K over our purchase price. We renovated the main floor top to bottom with new electrical and plumbing for $35k. This leaves $48k with no basement. The house next to use with the same property size and main floor sq ft was assessed at $542k and the only difference is a finished basement.
 

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Discussion Starter · #19 ·
So you are thinking of a finished basement in a flood zone? Would not be anything I would consider?
Will you even get flood insurance?
Does the foundation have footings?
how far would you have to get down if you were just levelling the dirt with the footing?
You do not just dig lower than the footing, you start underpinning 4 ft sections of the footing.
How will you get the dirt out, where will you put it when you get it out?
To clarify, I say flood zone because the insurance company considers it a flood zone. there was a flood 9 year back which was a combination of a multitude of errors by the city. this is the only flood on record and the city/ province is spending 14 billion on flood mitigation infrastructure so that is does happen again.

No footing on the current foundation.

I would need to dig 4' down to level the entire basement to the area that was already dug out.

The current area has already been dug out below the foundation wall. If you refer to image basement 2 and basement 4, it should the area where the cedar wall has been install below the foundation wall to hold back the dirt.

I will use buckets. I've got nothing but time.
 

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To clarify, I say flood zone because the insurance company considers it a flood zone. there was a flood 9 year back which was a combination of a multitude of errors by the city. this is the only flood on record and the city/ province is spending 14 billion on flood mitigation infrastructure so that is does happen again.

No footing on the current foundation.

I would need to dig 4' down to level the entire basement to the area that was already dug out.

The current area has already been dug out below the foundation wall. If you refer to image basement 2 and basement 4, it should the area where the cedar wall has been install below the foundation wall to hold back the dirt.

I will use buckets. I've got nothing but time.
That is what the pictures looked like, I was hoping you would explain something different.
I think it is way to dangerous to be just start digging there, with out a good plan for safety.
Can you draw a sketch of the shape and size of the space and show where the wood walls are now?
 
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