how to slope concrete?

[tech]

so i've got finish grade for my monolithic slab and i'm diggging the trenches and setting the forms this weekend. this slab is for a 2-car 24x25 garage. my questions are... how do i slope the floor for drainage towards the overhead doors? how much of a slope should i do?(i was thinking 2" back to front)

BTW i am not new to flatwork as i spent a few months doing it with a local construction company, but since i was just a peon i did not learn some of the more technical stuff like this.

slope options:

1. slope the forms and sreed to top of forms. this way will create a slightly wedge shaped slab and will need to be componsated in wall framing.

2. set the forms level and screed to top of forms and then "create" slope by hand.

3. any other way!

 

[Egan]

I would think your dirt/fill would have to be sloped otherwise you would end up with a pad of uneven thickness.

 

[PAToyota]

Definitely slope the underlayment - stone or whatever. What I did was build up a low masonry wall and then pour the slab to the inside of it. That allowed me to slope the floor but still have a level start for my wall framing. Also, you then can wash the floor down without getting the framing/drywall wet.

I would not try to build a framed wall on a sloped slab. Some areas may not even allow it.

 

[tech]

i can't build a block wall to frame on because it has to be monolithic. that is my issue.

 

[PAToyota]

Going to be hard to slope the floor in that situation.

 

[indyjps]

how much slope are you wanting,

 

[tech]

code says it has to slope but does not state how much. i personally don't care if it slopes.

 

[bahamasair]

code says it has to slope but does not state how much. i personally don't care if it slopes.

If they dont have a # that they want it to slope at do a 1/4" overall. That should be close enough to still frame on I think you will find they have a minimum pitch you have to slope at though

 

[xsponge]

Set forms level, then set screed pipes on the interior of the slab with slope towards doors.

 

[C_F]

Most of the builders around here pour the footers for the walls first, so the walls end up straight, then pour the floor later. Same sort of thing as building a block wall & pouring the floor against that, but cement instead of block.

When they built my house, the entire house (with attached garage) was 80% done before they poured the garage floor. I can't think that it was easy to finish the cement with the walls in the way, but they did it.

 

[Charles (in GA)]

code says it has to slope but does not state how much. i personally don't care if it slopes.

How strict is the building inspection? They may not care either.

I told my buiilder "I want my floor to slope just like the code says" all the while shaking my head from side to side. The building inspector could have cared less.

Charles

 

[Egan]

I think I remember my contractor telling me the floor was going to slope 2%, but my memory is not what it used to be.

 

[tech]

Set forms level, then set screed pipes on the interior of the slab with slope towards doors.

can you explain more about the screed pipe method? (i googled it with no luck)

 

[xsponge]

You aquire a 1 1/2" pipe 10' to 12' long or shorter if the need be. Then set a row of stakes 1 1/2" lower than the grade of the concrete, put a nail in the top of the stake at each end standing straight up about 3/4" so your pipe will stay on top of the stake. Run your screed, 2X4, whatever you are using to grade the concrete on top of the pipe. the pipe would be in the middle of the garage running paralell to the out side form. After you grade the concrete you remove the pipe leaving the stakes in the concrete. Some people will then pound the stakes in, I have allways just left them. Throw a little concrete in the void left by removing the pipe and finnish. I would suggest that go look at a floor pour where the contractor is using screed pipe, so that you may get a first hand idea of what it is.

 

[Donzi4me]

You can set the forms level and snap a chalk line on the inside of the forms for the finish grade.

 

[tech]

You aquire a 1 1/2" pipe 10' to 12' long or shorter if the need be. Then set a row of stakes 1 1/2" lower than the grade of the concrete, put a nail in the top of the stake at each end standing straight up about 3/4" so your pipe will stay on top of the stake. Run your screed, 2X4, whatever you are using to grade the concrete on top of the pipe. the pipe would be in the middle of the garage running paralell to the out side form. After you grade the concrete you remove the pipe leaving the stakes in the concrete. Some people will then pound the stakes in, I have allways just left them. Throw a little concrete in the void left by removing the pipe and finnish. I would suggest that go look at a floor pour where the contractor is using screed pipe, so that you may get a first hand idea of what it is.

so are you sloping the the sreed pipe so when you run on top of it the slab grade slopes as well?

 

[xsponge]

Yes, that is exactly what I am saying.