I have an old stone/stucco home (80 yrs) in the Philadelphia area with a panel/glass-enclosed front porch on a concrete slab. In the winters it’s been suffering fom frost heave so I decided to excavate around one side to see what’s up. It turns out that where the porch columns are resting the concrete was poured over stone piers that go down about 3 feet which is below the frost line. However, in between the piers the concrete appears to be poured right over soil! I really don’t want to prop the porch roof up in the air and do an excavation/repour because I spent a lot of time in the last few years rebuilding the top of my lovely, ignored (by the last owner), and now repaired/repainted porch (I know, I did things @ss backwards – shoulda started from the bottom and worked my way up).
Here’s my crazy plan – tell me what you think:
1. Excavate vertically down from the edge of the concrete pour to below the frostline (about the same depth as the piers).
2. Excavate under the porch about 8 inches in and straight down.
3. Put some rebar vertically up into the concrete ‘ledge’ I just created.
4. Make a form all the way down to the bottom and pour concrete into just above the ‘ledge’ so I can be sure I got it in all the way underneath this ledge and have the porch rest on it when it’s hard.
If anyone would like me to provide a drawing of what I had in mind I would be glad to do so.
Thanks in advance for your thoughts and minimal “what the %^@% are you thinking” comments.
ITGuy (the poster formerly known as Tom@Home)
Replies
If the piers seem sufficient to support the porch you might considering just excavating under the shallow portion and backfilling with pea gravel or styrofoam blocks or some such. Of course, this assumes that the FLOOR isn't the real problem, vs the edges.
Dan's right...you're assuming that the problem is confined to the outer 12" of the foundation. If in fact it is, then your plan may work.
Why not temporarily support the roof with beams through the windows, then cut out the foundation and re-pour it. Or do your plan for the perimeter, then saw cut the floor and remove the middle section, and replace it over a suitable fill.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Dan, Ed:
Thanks for the input - I'm afraid that I do think the whole floor needs to be reconsidered, not just the edges. Since the cracks in the tile (the little 1" square guys, can you believe it? must be a million of them!) sitting on top of the floor extend in several directions toward the center of the floor I'm probably just suffering from wishful thinking to believe I can fix this from the edges.
I'll have to really consider doing this the right way, and there is only one right way - excavate all of it and repour. Gentlemen, to your shovels!
ITGuy
Nah, just put down a membrane, cement board underlayment, and tile over the whole mess.