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Porch Concrete Cracking

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A buddy of mine bought his house about a year ago and is complaining that the concrete porch at his front door is cracking. The house was brand new when he moved into it and apparently others in the subdivision have had the builder rip up their driveways and sidewalks and have them re-done. 

Anyway, he asked me what I thought and if I could right him a letter. I said hell no to the letter, at least not with my stamp on it (I don't enjoy getting into pissing contests), but I did say I write him something up letting him know of the possible reasons for the cracks.

The porch is a 4" step up cast monolithically with a 4-5" slab on-grade driveway/sidewalk. The porch is a semi-circle in plan. The crack is along the circumference of the semi-circle at the base of the step about 1 inch outside of the curve in plan (side walk level- not on the porch). When the crack reaches the end of the semi-circle, it goes out 45 degrees until it hits the side of his house.

I suspect they used welded-wire fabric for the reinforcing and did not provide a curved bar along the circumference of the porch step which initiated the cracking.

Other reasons I was going to list as possible causes are inadequate frequency of weakened plane joists, lack of greasing dowels at construction joints, soil movements, & lack of minimum reinforcing.

If anyone can hazard a guess to the likely cause based on my description or come up with additional reasons, I'd appreciate it. I told him that structurally, it is likely nothing to worry about, but the guy did spend 850 grand on a house and he has cracks right at the entrance to the home. Plus, with the poor reputation of the builder, he is hoping something can get done to fix it.

Oh yeah, you Texans, that 850k equates to a 4 bedroom, 3000 sq.ft house in lovely San Ramon, CA. Now you are really jealous aren't you. (grin)

Thanks in advance,
-gerard
San Francisco, CA


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