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Missing foundation, what should I do


doublezero's Avatar
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07-20-09, 06:07 PM   #1  
Missing foundation, what should I do

Underneath this bathroom floor, when I removed the tiles I found water damage, mold, etc. and ripped up the moldy floorboards to find this. There's no foundation underneath a section of the bathroom. There's a basement underneath half of the bathroom, but the rest of it, it's just dirt. I dug some of the dirt out, hoping to find some kind of foundation, but haven't found any. The dirt appears to be the only foundation. And since it's just dirt leading to outside, the joists in this area are rotten and eaten away.



In these pictures, the normal basement starts roughly where you see a toilet pipe with a red plastic bag stuck in it. There's around 6' to go before you hit the basement floor. From there toward the top of the photo is the missing foundation I'm talking about.




So I wonder what I should do before I put down a new floor. There is probably more than one way to deal with this. I'm looking for a good way to fix this problem which does not require a structural engineer or any crazy expenses or complications like that.

Should I pour cement in this hole? What kind of cement? Every store I've seen cement being sold in does not sell sand. They sell only these pre-mixed bags. How far should I dig down, how much dirt should I remove first? How do I keep the cement from dripping past the point where there is a wall in the basement and onto the basement floor? (I've never poured cement before. I don't know how it's done.) Should I insulate the ground before I pour cement there? How? Should I use a vapor barrier? What kind?
Should I bulk up the rotten joists? By sistering? Or will burying them in cement be good enough?

The more details, the better, I actually don't know what you're supposed to do in this case.

 
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07-20-09, 06:30 PM   #2  
Wow! That dirt is too close to the joists. I would dig it out more, trying to find a footing concrete below the brick walls. Possibly removing some of the wall from basement/crawl (if you call it that), if possibly. Block-- or poured concrete wall?

Ideally, excavate 2-3' below the joists, open from the basement for air ventilation. Install a 6mill. vapor barrier on the dirt, and insulate fiber batts the floor joists with kraft paper towards heated bathroom, held up with wires.

Replace any damaged/weak joists. Also possibly the rim board with a treated one against the bricks.
Also need a new header at access to new crawl when removing bearing wall section under area, for new doorway opening. Be safe, G

 
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07-20-09, 07:00 PM   #3  
Posted By: GBR in WA Wow! That dirt is too close to the joists. I would dig it out more, trying to find a footing concrete below the brick walls. Possibly removing some of the wall from basement/crawl (if you call it that), if possibly. Block-- or poured concrete wall?

Ideally, excavate 2-3' below the joists, open from the basement for air ventilation. Install a 6mill. vapor barrier on the dirt, and insulate fiber batts the floor joists with kraft paper towards heated bathroom, held up with wires.

Replace any damaged/weak joists. Also possibly the rim board with a treated one against the bricks.
Also need a new header at access to new crawl when removing bearing wall section under area, for new doorway opening. Be safe, G
The basement wall is brick, just like the bricks shown in the picture.

Replacing the damaged joists: do you mean replace the entire joist? That sounds like I would have to remove all the floorboards all the way to the other side of the house. And then replace the joist, hoping I don't find another problem when I rip up the other floorboards. Hoping there will be something solid to attach the new joists to. This sounds like something you need a permit for and a structural engineer. It's well beyond my experience.

Removing the basement wall to get at the dirt behind it? Now I know something will go wrong if I try that.

 
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07-21-09, 05:03 AM   #4  
G, what would be the problem in doing the pour thing on the higher place? He could cut the joists just inside the area so the tails would sit back on the pour, and then sister or rebuild the floor totally from that point using a header joist on the cut tails. Man, I'd hate to dig all that out, not knowing what kind of degradation I would be causing to the exterior walls.

 
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