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-   -   Extending a Concrete patio (http://www.diychatroom.com/f19/extending-concrete-patio-72309/)

luweee 05-28-2010 06:57 PM

Extending a Concrete patio
 
I plan on adding on to my existing patio. My current patio is 12X12 .. the house is yrs old .. my current 12x12 patio needed to be mudjacked last year. the current 12x12 has never cracked. Since mudjacking the patio looks fine... no probs. We want to add on to all 3 sides of the patio now.

I live in Omaha Nebraska.

I had 4 contractors come out and bid it 1 had 15 yrs experience the other 3 had 20 or more years experience. 3 of them say they want to put pins (drill a hole into the foundation and put rebar out X number of feet) and attach it to the house..

1 contractor says no... he wants to just use expansion material so will float and wil not use the rebar.

What is the right way? will this hurt my foundation if they do drill into it?

joed 05-28-2010 07:38 PM

No rebar to the house only to the existing slab to keep the new and old in line.

luweee 05-28-2010 07:44 PM

Joed

So if they are attaching this to the house... this is the wrong way? and will harm my house?
just trying to understand why 3 out 4 are doing this?

Thanks for your response. much appreciated.

Trainer019 05-29-2010 01:28 AM

Depending upon where you live and the soil type will dictate if pinning a patio slab, sidewalk or driveway to your home foundation is acceptable. Where I live (Saskatchewan) the soil is very heavy clay and shifts alot so pinning should NEVER be done, (but still some do, go figure). The foundation of your home will never shift and settle at the same rate as the slab that is attached to it so why try and force it to by pinning it there. A horizontal slab that is pinned to and falling away from a vertical wall will probibly in time exert enough force to create a fracture and cracks and fractures in foundation walls are not good not easy to fix. Besides, why take the chance, let it float.

luweee 05-29-2010 02:31 AM

!!
 
Quote:

Originally Posted by Trainer019 (Post 448361)
Depending upon where you live and the soil type will dictate if pinning a patio slab, sidewalk or driveway to your home foundation is acceptable. Where I live (Saskatchewan) the soil is very heavy clay and shifts alot so pinning should NEVER be done, (but still some do, go figure). The foundation of your home will never shift and settle at the same rate as the slab that is attached to it so why try and force it to by pinning it there. A horizontal slab that is pinned to and falling away from a vertical wall will probibly in time exert enough force to create a fracture and cracks and fractures in foundation walls are not good not easy to fix. Besides, why take the chance, let it float.


I live in Omaha Nebraska and my soil is all clay... so I guess this applies to me.
Trainer and Joed are either of you contractors. You seem to both agree. looks like I will ask them not to pin it to the house.

Any other takers on this?

THanks Joed and Trainer

stadry 05-29-2010 05:42 AM

no pins to the house,,, that's why they make expansion jnt material,,, nor would we do that here in atl.

IF the frost decides to move your new very fine patio, you don't need that stress transmitted to the home's conc foundation walls,,, if masonary block, absolutely not !

joed 05-29-2010 08:22 AM

Not a contractor. Frost heave is also a factor that would be another reason for not pinning to a a foundation.

jomama45 05-29-2010 06:52 PM

No doweling to the house period, unless for some reason, you put more value in you're patio than foundation.

Frost heave is one concern, but settling is another. I was called to look at a "minor" problem on a patio in a very upscale neighborhood a few years back. Just a few "small pops" in the patio near the house. When I got there, I can see the tops of rusty rods at each "pop." The backfill under the patio settled, & there was no way on earth a few 1/2" dowels where going to hold up the patio, so they stayed in the foundation & just destroyed the patio.

I've also seen many, many dowels into block foundations through time, especially at garages/driveways. All that happens is the 1/2" hole gets knuckled out to a 2"+ hole, defeating the purpose.

As stated, expansion joint at 2 disimilar sections of concrete, or plan on putting a frost footing under the patio.

PS, a few of the poured concrete foundation contractors here will not warranty any foundation problems associated with non-frost protected flatwork doweled into the foundation. It's stated right in there contract, and is usually all I need to tell a HO with a new dwelling when asked this exact question.


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