anchoring patio slab to foundation?

Old 07-03-20, 08:16 AM
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anchoring patio slab to foundation?

Getting a patio slab poured next to existing foundation. Some contractors recommend anchoring slab to foundation with rebar. I'm concerned about shifts in the slab compromising foundation. Am I worrying over nothing? Is it OK to let them shift independently, or does it need to be anchored? Thanks.
Old 07-03-20, 08:26 AM
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The sole purpose of anchoring it would be to ensure it doesnt sink. Ground around the house perimeter is disturbed earth so it is prone to settling. But a pad is not on a foundation, so it can heave with frost, and any attachment point would be like a hinge. So rather than attaching it, IMO it would be better to anchor an angle iron to the house that would be flush with the bottom of your form, let a little sand overlap the edges so that concrete doesnt necessarily stick or lock onto it. You usually want an expansion joint between the house and the pad so that the pad does not exert pressure on the house. That joint gets caulked later.

The new concrete pad would then be supported in back so that it cant sink, it's not touching the house so it cant crack the foundation.

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