Concrete Patio - Knitting Rebar into Foundation

2919 Views 12 Replies 8 Participants Last post by Rubespur, Jun 20, 2020

Rubespur

Discussion Starter · Jun 18, 2020

Hi All,

I hope everyone is doing well during this pandemic.

I'm hoping to get some advice concerning a new concrete patio I would like to have installed. We have an existing patio that has settled and cracked, and we would like to replace it with a 17' x 16' slab that would be 4" thick.

We've had one quote so far from a concrete contractor who said that he would tie the rebar of the new slab into the house foundation. I'm no pro, but the idea of drilling holes into a foundation got the hairs standing up on my neck, so I called the next concrete contractor coming out in a few weeks to give us a bid, and he said over the phone he would do likewise - tie the rebar into the foundation.

I've done some internet searches, and it seems to be a 75%-25% split with most people saying not to tie the rebar into the house, with the idea that when the new slab settles, it will add tension to the existing foundation wall and possibly cause cracks and problems down the road.

I would love your insights and advice. I'm terrified of wrecking havoc to our foundation wall. Our basement is bone-dry - we've been really fortunate in this area. Maybe I just need some reassurance!

House is a 1989 build with concrete foundation walls with tie rods inserted through the walls, if that helps give any technical information anyone needs. We are in Wisconsin - so easily 30 - 50 degree temperature difference on some days...

Cheers,

~R

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Nealtw

· #2 · Jun 18, 2020

Just have them run over the fill with a plate compactor.
The real problem doesn't show up for years when the steel that is exposed between the foundation and the slab rusts and expands and blows out the concrete.

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joecaption

· #3 · Jun 18, 2020

No way would I ever "tie" it into the foundation!
A slab like that is going to move over the seasons, a foundation should not.
The reason your old slab failed is because is was not prepped right under it before it was pored and likely no, or not enough cuts made in the slab to allowed it to flex.

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bob22

· #4 · Jun 18, 2020

I’ll try to send a pic of the six places mine was tied in and all six have popped out the surface of the patio. Concrete guy said inspector forced him to do it; wouldn’t have otherwise.

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Rubespur

Discussion Starter · #5 · Jun 18, 2020

Thank you all for your replies and bob22, I would be grateful to see those pictures!
~Rubespur

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Nealtw

· #6 · Jun 18, 2020

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huesmann

· #7 · Jun 18, 2020

^^ That appears to be an instance of insufficient cover.

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Nealtw

· #8 · Jun 18, 2020

huesmann said:
^^ That appears to be an instance of insufficient cover.

Same effect if you can't seal the join between house and slab.

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Bondo

· #9 · Jun 18, 2020

joecaption said:
No way would I ever "tie" it into the foundation!
A slab like that is going to move over the seasons, a foundation should not.
The reason your old slab failed is because is was not prepped right under it before it was pored and likely no, or not enough cuts made in the slab to allowed it to flex.

Ayuh,...... Ditto,..... Slabs, 'n decks should be independent from the house,...

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dj3

· #10 · Jun 18, 2020

When you do a room addition or any addition, you tie the new slab with the existing footing, 12" deep, that's the code. A patio slab or a walkway - no.
What's the difference? A room addition has a footing all around it, patio slab and walkways don't.

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stadry

· #11 · Jun 19, 2020

room addn's also conditioned space - different animal
NO ONE ( other than the idiotic aforementioned inspector ) would EVER specify as your ' concrete expert ' suggests

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bob22

· #12 · Jun 19, 2020

Here are two spots where the pins have broken through the surface.
First:

and, other one:

I sawed through the rebar a year or two ago to lessen the effects but the damage is already done.

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Rubespur

Discussion Starter · #13 · Jun 20, 2020

Thank you all! This is helpful. I won't be allowing anyone to tie a new slab into the foundation wall. It didn't feel right in my gut and your responses affirm that. Thanks!
~Rubespur

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