I’m pouring a cement pad that’s 11 1/2 ft x 11 1/2. What is the minimum depth I can safely get away with?
May 23, 2010 by
Filed under fiber cement siding
Also, I’m pouring this slab inside a dirt-floor barn, that already has a concrete foundation around the sides. Can I pour the new concrete right butt-up to the old concrete foundation? or do I need to use some kind of spacers? If so what kind? wooden? how big? I plan on using the fiber-based mix so i don’t need re bar.
Ok, so i’ll be sure to put down atleast 6″ of gravel 1st, and put “expansion joints” around all the corners, between where the two concretes will meet. Should I also run an expansion joint down the middle? This isn’t for a car, this is just a floor in a utility room in a barn
Minimum? You’d be talkng 4 inches AT LEAST. but, best be on the safe side. Are you going to be sectioning the slab?
you can butt em up against each other but it will make a crack there. minimum three inch depth. id go with four. definitly install expansion joints. you can put in adatives to avoid cracking at the seem
you tell us a lot …but not what you are going to use it for …..its not long enough for a car …there-for you you will get away with 100mm(4″)…but remember ..you cant pour concrete onto dirt …you must put down hardcore first …150mm(6″)..if you don’t it will crack …im a builder in uk
Put 4 relief cracks in and trowel around the edge Between new and old cement. 4 inches deep would work good.
31/2″…the width of a 2″ x 4″
If you do not want the slab to move up or down, drill into the existing foundation and install #4 rebar dowels every 24″ and with-in 12″ of each corner. Epoxy the rebar into the existing foundation at a depth of 2″. Let the rebar stick out 4″. Tie a #3 rebar perpendicular to the dowels, 3″ out from the existing foundation around the entire perimeter of the slab. You do not need 6″ of gravel. 31/2 ” of sand will do fine. It will not raise the height of the concrete floor as much. Or if you are removing dirt to compensate for the thickness of the 6″ of gravel, you will have to remove far less dirt with 31/2″ of sand.
pour 4 in. thick and use expansion joint…if this floor has been walked on and settled for years i would scratch it down and get a flat grade and pour it on the dirt…you can dig it down and add gravel but its already compacted from years of being used and walked on…
All these answers would be more or less correct if it was going to be a garage or something else you would drive on, but it obviously isn’t if it is only 12′ X12′. 3″ is fine for a shed.
Just make sure the ground is flat without any “fill” dirt and pour some concrete in it.
Put some 6″ X 6″ concrete wire in it and it will be fine.
It is going to take about 1 and 1/2 sq. yards on concrete.
Don’t worry about the edge…. you can fill in the small crack later with caulking if it bothers you.