Expanding current concrete patio

ballengerb1 · Apr 4, 2007, 02:48 PM

You new concrete patio should have grooves troweled into it no more than every 8 ft. This will control and guide the crack since nothing on earth has ever prevented concrete from cracking. Death, taxes, concrete cracks, pretty much 100% guaranteed. The new slab should have at least 6" compacted base such as fine gravel or screenings. Never pour on dirt! You should match or better your old slab with at least 4" of concrete with wire mesh in the concrete. Have you calculated your yards yet? This will be a lot of weight to move if you pour yourself. 10 friends and a keg might come in handy.

Kstar4u · Apr 4, 2007, 10:05 PM

Quote:

Originally Posted by jp7810

I have a 10 x 10 concrete patio that sits against the house. I want to expand the patio on the three uncovered sides. I live in the mid-west( Lafayette, Indiana) so I need to account for hot, humid summers and cold freezing winters.

My questions are:
1)Do I make the surrounding additions one big slab or break it into three separate slabs.
2)How do I tie the new concrete into the existing patio to prevent cracking and make it look good.
3) How deep do I need to dig the new slab area? Do I need to put down stone or pour onto the leveled dirt?

Thanks for the help.

Here's my recommendation..if the new slab(s) only abuts the existing slab and one other side (a free side for each of the three)... A "good and deep" control joint will be all that is necessary at the edge of the original slab, except for one [probably best to be the one opposite the house wall] (control joint...yeah know... That little slot... It's going to crack... We hope there). If you want to... You can use TREATED 2X4 forms at that location and leave them in as an exspansion joint. You can even use 1X4's. But hey.... It's your yard and only the best... Right? Go for a brick or stone ribbon instead of control or exspansion joints!

Kstar4u · Apr 4, 2007, 10:12 PM

Quote:

Originally Posted by jp7810

I have a 10 x 10 concrete patio that sits against the house. I want to expand the patio on the three uncovered sides. I live in the mid-west( Lafayette, Indiana) so I need to account for hot, humid summers and cold freezing winters.

My questions are:
1)Do I make the surrounding additions one big slab or break it into three separate slabs.
2)How do I tie the new concrete into the existing patio to prevent cracking and make it look good.
3) How deep do I need to dig the new slab area? Do I need to put down stone or pour onto the leveled dirt?

Thanks for the help.

Sorry... Forgot the other part of the question....To Be Safe... And it's not really that much more work or $... Grade the area of the new slab... Make it two extra inches deep (you can use 2X6's if it's easier to do) and put a vapor barrier (plastic sheeting) and two inches of sand in the form before you pour... You'll probably have all the neighbors wanting you to replace their cracked concrete.... Remember though DEEP CONTROL JOINTS NO LESS THAN EVERY EIGHT FEET BOTH WAYS!

jp7810 · Apr 5, 2007, 10:48 AM

Thanks for the feedback.

Could you guys explain a control joint. Is that the joint that is put in with a trowl or is that the joint that has the material to compensate for expansion and contraction.

Kstar4u · Apr 5, 2007, 03:52 PM

A "Control Joint" controls the crack (establishes a weak line in the concrete that should crack before the surrounding thicker slab), an "Expansion Joint" uses a softer-than-concrete material that allows the concrete to expand or contract without buckling.

ballengerb1 · Apr 5, 2007, 06:07 PM

Star4u is in CA and there isn't as much worry about frost in the high desert. It is going to crack anyway but, where frost is an issue, a 6 " base of screening is the proper approach. Iguess we'd need to know where you live to be more exact.

jp7810 · Apr 6, 2007, 06:28 AM

I'm in Lafayette, Indiana

ballengerb1 · Apr 6, 2007, 09:10 AM

Yep, I'm pretty sure it freezes in IN. It was 24 last night.

Expanding current concrete patio

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