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Poured cement patio

Posted by cateyanne (My Page) on
Mon, Jun 24, 13 at 11:28

Just had the first contractor over to discuss putting in a concrete patio in our backyard. We are total novices at this, but want to make the most knowledgeable decision. We have saved our money for this project and it's a long time coming, so it's important that we get the most for our money, but I want it to look good for a long time, so quality matters.
This guy says for an approx. 23X19 patio he will put expansion joints where the concrete butts against the house and garage. He will excavate the first day to get it somewhat level, there is a significant grade. That first day he will also bring in 57 stone and compact it. Next day he will pour the concrete and use 6x6 grid steel wire mesh. He will also cut joints to help prevent cracking approx. 1/2 way through the 4" depth of the concrete, and will make sure there are no areas larger than 10x10 without the cuts. The patio will be along the back wall of our house, which is brick and along the detached garage wall, which is cement block. It will have a serpentine curve to the outer edge. And we are thinking of having a pattern stamped or the edge stamped with a pattern.
I wanted to know how this sounds to others. What other questions should we be asking when we speak to him again, and to other contractors we see? I did bring up a concern about the grade, because the area where the table and chairs will be is currently an obvious slope. I said that I didn't want to be sitting at the table and feel like I'm on a slant. He didn't give me a clear answer, just said the grade will be less, that's what all the excavating and stone base will do, there will need to be a bit of a grade for water run off and he would "try" to have that not happen. What do you all think of what information I have so far? Oh, he also said he cannot guarantee it won't crack, even if it happens right away, which I find surprising.
Thanks


Follow-Up Postings:

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RE: Poured cement patio

Call some more contractors. If you have a steep slope you may need some type of retaining wall to hold the area he's building up. It all depends on how steep the grade is.
Also, where do you want the finished surface? Will there be a step down from the house or is it level with your doorway? Do you intend to have decorative stone added at a later date?

I wouldn't be happy with the answer 'try'. He should be able to achieve enough slope for water runoff yet still have your table and chairs feel level.

Ask for a list of the contractors previous jobs and talk to the homeowners.


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RE: Poured cement patio

The contractor should be able to give you a firm idea of the pitch of the slab. 1/8" per foot is fine here in VA, but I know some northern climates prefer to see 1/4"-1/2" per foot of fall. As to how the raised edge is handled they can do what's called a turndown edge pretty high (12-18") but you'll need a way to deal with the grade then.

As for cracking, it's concrete. Concrete WILL crack, it's just a question of when. Anyone who tells you differently is blowing smoke.


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RE: Poured cement patio

To prevent separation from the house you may want to drill and attach to the foundation. Might also want pillars to prevent settling. I am in the process of building a cemant rock covered patio with a pergola and am attaching a picture.


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RE: Poured cement patio

CharlieBoring I'm glad you mentioned that. One person we talked to briefly said he would drill rebar directly to the house foundation. I have been doing some research and have read some posts that say this is not a good idea because it could damage the foundation. Am I misinformed? Maybe I'm comparing the wrong kind of patio to foundation attachment? So, you are saying the poured cement patio may move away from the house and garage it will originally be laid up to, unless it is attached directly to my foundations? What will the purpose of the expansion joint be the contractor told me about? Thanks so much!


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RE: Poured cement patio

I had them drill my foundation and attach my patio because I have seen patios settle and separate from the house. Separaton joints allow expansion and retraction without cracking, as a rule.


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RE: Poured cement patio

Thanks, is there a correct type and quantity of stone that should be laid before the cement is poured? Does the kind of cement matter? What are those requirements? how deep should the cuts be, if the cement poured is 4"?


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RE: Poured cement patio

the most recent contractor told us that he would not drill into our foundation because it is block. He has no problem drilling into a cement foundation which is on newer homes and has done so without hesitation, but says a block foundation, like those found in older construction may not be able to handle the movement that may occur with being attached to the patio. He has seen block foundations severely damaged with this application.


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RE: Poured cement patio

I would not underpin a concert slab into a block foundation wall, especially in northern Ohio.

The contractor that told you he could not guarantee against cracking is being very honest and his plan is solid.

The type of concrete is very important. Not all grades of concrete are the same. Cement to concrete is like flour is to a cake. Not all cake recipes are the same, similar but not identical. The grade of concrete is dependent on what raw materials are available locally to you. Whether hardeners are added as well as a myriad of other factors including the type of cement used and what other aggregates are used to produce the product where you are. Educate yourself as to what grades of concrete are best for you in your climate zone and what is available from your area. ASTM (American standard testing method) if I recall my acronyms correctly, strength is a number that is important. It tells the hardness of the final product. Moisture content is a number as equally important. These numbers are what the final products quality aim is and the real number is after analysis is done after production.

All concrete will crack, eventually. We are in the same zone as northern Ohio and use a 1/4 " per foot slope away from the building and to the lowest level at one end. You would be surprised that some crews mistakenly slope to the house, oops. The more of a slope away the better.

You might want to consider a colour tint in the concrete that is easily done.


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RE: Poured cement patio

Thank you Southern, lots of good information and much appreciated. So far everything this contractor is saying is turning out to be sound advice. Frightening how different the others opinions were about what the correct methods and materials would be. We are talking tinting the concrete, so you're right on target.


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