footing questions

[stinkity stoink]

Ok I am in the planning process of my garage. It is going to be a 24'x24'. I will be building it myself with the help of a few friends. I have limited experience with concrete work though. I have recieved prices of a little over $10,000 for the footings, walls to come up 1' above grade and a 6" slab. This doesn't fit into my budget.
My question is the footings first off. The grade of the land is what screws me up. It is about 5' lower in the rear when you go back 24'. What is the best way to dig the footings. i figure with that kind of grade the concrete will want to run to the back when i pour the footings. Is there a trick or a certain way I should go about this.
When the footings are done I will be doing poured concrete walls. I have acess to the forms. Near the front of the garage they will come up 1' above grade. At the back it will be about 5' above grade. Of course I will use a lot of the dirt I dig up as fill to level out the inside of the garage.
Any advice on the footings ?
Thanks...
Dave

 

[IDASHO]

Check out my garage built site. It shows exactly what you need to do.

Any time you have a dramatic change in grade, you have to 'step' the footers on the slope.

http://www.bonnefinstudios.com/kwb/paradise/garage/

Like this...

 

[tcianci]

Since the forms need to sit vertically, the footing surface needs to be level, not sloped, you need to "step" the footings. Since you have access to the forms, plan your steps in even increments of whatever form panels you will be using. The important thing is that the base of the footings are below the frost line in your locale. The local building dept can tell what that depth is. For example, if your area calls for the footings to be 4 feet below grade, then the total height of your pour at the back of the garage is going to be about 8 feet because you said you were going to be about 5 feet above grade, 1 foot for the footing and 8 feet for the walls, 3 feet of hich will be below grade and 5 feet above. I would advise to raise the grade around the back of the foundation if possible. It will save you a lot of concrete since you wouldn't need to go as deep wit the footing and you would end up with a shorter pour. Raising the grade will also limit the number of steps in the footing required to accomodate the change in grade since the change is now less severe. Also make certain that the material you plan to use to backfill the garage interior is suitable for the purpose. You want to use only good gravel that will drain well and not retain moisture, on top of that, about 6 inches of 3/4 inch washed stone, graded to a level about 4 to 6 inches below your finished floor. Typically you will have a dropped down section of your stem wall in the area of the garage door. Be sure to clean all the backfill off of the top of that dropped area and form across it and allow your floor pour to go right down to the top of the stem wall.

Also consider fastening a 1x1 angle iron on the inside surface of your stem wall that spans the garage door opening. Set the iron at the finished floor height and this will allow the finished floor to be an inch higher than the apron area. The garage door will close on the lower area and the 1 inch step ensures that you wil not get wind driven rain running up under your door onto the garage floor. Short pieces of re bar welded to the underside of the angle are used to hold the angle in place in the gravel.

Hope this helps

 

[rieferman]

Also consider fastening a 1x1 angle iron on the inside surface of your stem wall that spans the garage door opening. Set the iron at the finished floor height and this will allow the finished floor to be an inch higher than the apron area. The garage door will close on the lower area and the 1 inch step ensures that you wil not get wind driven rain running up under your door onto the garage floor.

The concrete guy that I used did this exact thing - turned out great, and it really does help. Even a hard driving rain (and the prevailing wind in my neighborhood beats the garage door side of the barn) doesn't have a chance of getting under the door.

 

[uhcrandy]

whenever I have done footings, they were formed "inground" with just the soil as the forms. Most codes allow this out west. You need to more care in the digging and it takes more time to ensure the edge, but there is no cost to forms. Just something to think about

 

[krooser]

whenever I have done footings, they were formed "inground" with just the soil as the forms. Most codes allow this out west. You need to more care in the digging and it takes more time to ensure the edge, but there is no cost to forms. Just something to think about

We do the same thing here in central Wisconsin... dig the the trench the width of the footings... in my case we dug a 24" wide trench for 10" thick poured walls.

 

[OccupantRJ]

You might also want to consider providing a "key" into the top of the footer when poured. This is basically a slot used to help lock in the stem walls to the footer when the wall is poured on top of the footer later.

 

[kbs2244]

I hire this stuff out.
But I don't think you can do stepped footings without forms.

 

[stinkity stoink]

Thanks for the responses guys . Great info I appreciate it. I screwed up my grade. At least I have a definite # now. i am getting more serious each day about building this. The total drop is only 2 feet. I was way off, but I measured today and thats what it is.
Where I am I need to be 3 feet deep on the footings. I spoke to a buddy and he is telling me to just dig the front 5' and the back 3 '. Or dig the front 4 feet and make the back 3' and level it out with the concrete.
I will just be doing a trench pour. No fourms for the footings. Than I will put the fourms for the walls right on the footings. As long as I get the footings level I should be in good shape and not have any problems. Does that sound about right.
I know it's a lot of hard work, but I am not afraid of that.
Thanks

 

[DRED]

I just build a 24x24 garage with footings and all. You should consider 26x24. The extra width is needed if you have 2 cars.

 

[twostory]

For the trench pour, hammer 18 inch rebar vertically into the ground every 2 feet. Then use a string (or transit) to set the top of the rebar at the same height over the footer. The top of the rebar will be at the height of the top of the footer.

Then when you pour the concrete, use a flat shovel the drag the top layer of the concrete level. You will feel the shovel hit the rebar. Then go over the footer with a magnesium hand float to smooth the top of the concrete.

This method makes it very easy to get the footer level.

 

[OccupantRJ]

I agree with Twostory. This is the way we usually reference the footing pour around here, and the rebar helps lock the footer to the ground even further. I usually set the rods about 3 feet apart, and most anything in the metal rod or bar category will work, as long as you do not have to satisfy the inspector's whims relative to using only rebar. I work in manufacturing, so I use old tubings, pipes, angle iron and such, since it will be buried anyway.

 

[stinkity stoink]

For the trench pour, hammer 18 inch rebar vertically into the ground every 2 feet. Then use a string (or transit) to set the top of the rebar at the same height over the footer. The top of the rebar will be at the height of the top of the footer.

Then when you pour the concrete, use a flat shovel the drag the top layer of the concrete level. You will feel the shovel hit the rebar. Then go over the footer with a magnesium hand float to smooth the top of the concrete.

This method makes it very easy to get the footer level.

I will do that . Thanks..

 

[pa30b]

consider fast foot from fab forms. A great way to go

 

[IDASHO]

For the trench pour, hammer 18 inch rebar vertically into the ground every 2 feet. Then use a string (or transit) to set the top of the rebar at the same height over the footer. The top of the rebar will be at the height of the top of the footer.

Then when you pour the concrete, use a flat shovel the drag the top layer of the concrete level. You will feel the shovel hit the rebar. Then go over the footer with a magnesium hand float to smooth the top of the concrete.

This method makes it very easy to get the footer level.

Do not be surprised if an inspector fails you on the pre-pour footing/stemwall inspection.

You are not supposed to have any rebar exposed outside of the concrete. Over time, that rebar will rust away, right into the footing.

 

[rinny_tin_tin]

Do not be surprised if an inspector fails you on the pre-pour footing/stemwall inspection.

You are not supposed to have any rebar exposed outside of the concrete. Over time, that rebar will rust away, right into the footing.

He is using it as a grade pin - so when he comes up to the pin, hit it with a hammer to bury it below the cement. The problem with this method is that if the ground is too soft, the pin will bury deeper, especially if you let any time lapse between setting the grade and pouring - especially if it rains. I'd pull a line too to mark the grade if you don;t want to use a board - but the board (and string ) is the best.

 

[IDASHO]

He is using it as a grade pin - so when he comes up to the pin, hit it with a hammer to bury it below the cement. The problem with this method is that if the ground is too soft, the pin will bury deeper, especially if you let any time lapse between setting the grade and pouring - especially if it rains. I'd pull a line too to mark the grade if you don;t want to use a board - but the board (and string ) is the best.

The rebar will still exit the concrete, into the soil.

The proper method if using such pins is to PULL them as you pour.

 

[rinny_tin_tin]

The rebar will still exit the concrete, into the soil.

The proper method if using such pins is to PULL them as you pour.

No...if you club the pin down as you pass over it with the leveling board, it disappears into the ground and doesnlt come back up. Its done that way all the time and I have poured much concrete and also witnessed the pouring of much concrete where that technique is used. That what grading pins are all about.

 

[IDASHO]

So you are pushing it all the way into the ground, PAST the footing?

Ive never seen it, or done it that way.

If I use grade pins, I pull them as I go.

 

[rinny_tin_tin]

So you are pushing it all the way into the ground, PAST the footing?

Ive never seen it, or done it that way.

If I use grade pins, I pull them as I go.

Yes...you see grade pins are most often used to mark some intermediate height between two points separated by a distance too long for a screed, for example say the rear and front of a garage slab that has a slope. When they get to the grade pin, the worker usually pulls the board around it to get the right height, and then punches it down with a hammer several inches below the mud. You can pull them too if you want, but it will likely take more effort to wrestle it out of the ground if you have a long piece of rebar serving as the pin.

 

[Racecarl]

I am in the process of builiding a 24 X 30. My lot only slopes about 1'. I was able to use a skid loader to level my lot to within 6" of level. I used a trencher and dug a 8" wide trench at 46" deep. Since I was planning to use hydronic heat to heat the floor, I wanted to put 2" of extruded polystyrene (the 250 stuff) in the inside walls next to the slab. Local code requires the wall to be 8" thick, so that meant I needed to shave 2" off the inside wall of the trench to place the insulation. I eventually got this done with a LOT of hand digging.

I then built forms from the existing grade up. My corners stayed exactly where they should have but the walls did not. I thought I had the forms braced pretty well, but I was wrong. In one place there is a 1" bow, but I can work around it.

If I had to do it all over again, I would have dug a 2' wide trench and poured a conventional footer. I then would have built the walls with insulated concrete forms and hopefully avoided all the labor and problems I had with building wood above ground forms. The only reason I stuck with the wood is because I have a LOT of it--I tore down an old barn to get the lumber for my project.

 

[Kevin54]

Ok I am in the planning process of my garage. It is going to be a 24'x24'. I will be building it myself with the help of a few friends. I have limited experience with concrete work though. I have recieved prices of a little over $10,000 for the footings, walls to come up 1' above grade and a 6" slab. This doesn't fit into my budget.
My question is the footings first off. The grade of the land is what screws me up. It is about 5' lower in the rear when you go back 24'. What is the best way to dig the footings. i figure with that kind of grade the concrete will want to run to the back when i pour the footings. Is there a trick or a certain way I should go about this.
When the footings are done I will be doing poured concrete walls. I have acess to the forms. Near the front of the garage they will come up 1' above grade. At the back it will be about 5' above grade. Of course I will use a lot of the dirt I dig up as fill to level out the inside of the garage.
Any advice on the footings ?
Thanks...
Dave

You can step your footers up or down. You just need to block them off at the end.
Do not use dirt as backfill inside of the garage. Dirt cannot be tamped down tight after being loosened up. That is one reason that footers have to set on undisturbed soil. You can dig a footer then try to fill up a low spot. Inside the garage area you want to use sand or stone to backfill. This will compact down. Dirt would take a few years to compact and then you end up with cracks all throughout your floor. I've seen it many times. Any flatwork you see always has stone or sand underneath it.

 

[uhcrandy]

About the grade pins, UBC (uniform building code) disallows rebar unprotected by concrete. The idea is that as rebar rusts, it expands, cracking the footer. I have seen this enforced and not. If you have a high water table or moist ground, it make sense. It is best to pull the grade pins.

 

[rinny_tin_tin]

About the grade pins, UBC (uniform building code) disallows rebar unprotected by concrete. The idea is that as rebar rusts, it expands, cracking the footer. I have seen this enforced and not. If you have a high water table or moist ground, it make sense. It is best to pull the grade pins.

I agree with it being undesirable for steel exposed above the concrete -- but, a good slam down with a hand sledge and the grade pin keeps company with all the other rebar. Its far easier for me to slap down rather than pull - especially when you have the chaos of trucks pouring, your up to your mid leg in cement, while trying to keep your balance on steel mesh.

 

[brownbagg]

Do not use dirt as backfill inside of the garage. Dirt cannot be tamped down tight after being loosened up.

I cant believe you said that, do they not let you play with sharp instrument too. Dirt has been the building block of everything built today. You need to refrain from making comments like this.

 

[Kevin54]

Do not use dirt as backfill inside of the garage. Dirt cannot be tamped down tight after being loosened up.

I cant believe you said that, do they not let you play with sharp instrument too. Dirt has been the building block of everything built today. You need to refrain from making comments like this.

And why is that? On flat ground and the right equipment outside you can get dirt compacted. In an area like a gartage basically all you have to use is a plate tamper. If you have clay like soil conditions and dry dirt, it will not compact like sand or gravel. Over a period of time it will eventually settle leaving voids underneath. Now if all you have is sandy soil, then that is a different story. You get East of the Mississippi then it is completely different dirt. I've seen garages crack in less than a year because they were backfilled with dirt. And the only reason they were backfilled with dirt was to save a few bucks over buying gravel.

 

[brownbagg]

I am east of mississippi, I am also a soil tech, It not that dirt cannot be compcated but that people have no quality in their workmanshp. dirt is an great construction material. The whole world is build on dirt. Just because your contact have issues with soil is not a reason for you to tell someone not to you the material. Its not soil the problem. Iits the unedcation workers that has been around your neighborhood.

 

[tcianci]

Guys Listen to Rinny, anyone who has an avatar like that knows his stuff.

 

[rinny_tin_tin]

Guys Listen to Rinny, anyone who has an avatar like that knows his stuff.

HAhahahahahhahahahah!

 

[tcianci]

As far as using "dirt" for backfill, everything is essentially dirt. The backfill needs to be compacted in layers and the thickness of those layers is determined by the type of soil you are using and the size of the mechanical tamper. The use of crushed stone under the slab is more for frost protection than for load bearing capability. We typically put about 6 inches of 3/4 inch washed stone under a slab so that the area stays well drained and less subject to frost heaving. Also as I have posted before it is important to pour your floor right down on top of the dropped sections of your frost wall so that water doesn't accumulate under the slab.

I was building my brothers garage and in the absence of a plate compactor, I advised him to puddle the daylights out of the fill in the garage so it would not settle later. He didn't listen to me and borrowed a plate compactor and ran that thing around on the fill until his eyeballs rattled out of his head. I told him again to puddle the daylights out of the fill or he would have trouble because the fill was way to thick to be compacted with a small machine. He still didn't listen but God interviened...That night we had a thunderstorm... one for the record books...the next morning, some areas of the garage had dropped 10 inches and overall it was about 4 inches lower. I have always used water to settle the backfill, however I'm talking about small slabs...26 x 30 max. otherwise you would go broke on the water! But it works fine.

 

[stinkity stoink]

thanks guys great info. I was planning on using the excavated dirt and compacting it down. I was also going to soak it like mad. I will also use 6" of stone with a vapor barrier and insulation because I am planning on radiant heat.