Arched steel building...yes or no?
- Thread starter MotorSeven
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MotorSeven
Elite Member
PAexcavator,
It's odd, 5 min ago i just got the same advise from a local contractor that is originally from Kentucky. The TN excavator said that i could form straight up ontop of the leveled fill, then go with an 8" tall x 25" perimeter footer then back-fill w/gravel to get the 4" monolithic. My KY guy said 'no way" that he would go 18" deep x 12" wide then make darn sure that the outside edge is graded in a manner to keep the water away from the slab due to the freezing problem you mentioned. He also does not like forming ontop of fill and recommends digging-in footers, but says that it can be done, sometimes with mixed long term results.
I hate going into something this important with such a lack of knowledge, but i assumed that those in the field would know what they are doing....shame on me! It looks like another trip up there to make sure this is done right.....{I Knew i shoulda bought a dozer...and a backhoe...and a......!!!}
Thanks for the info, i apperciate the help!
RD
It's odd, 5 min ago i just got the same advise from a local contractor that is originally from Kentucky. The TN excavator said that i could form straight up ontop of the leveled fill, then go with an 8" tall x 25" perimeter footer then back-fill w/gravel to get the 4" monolithic. My KY guy said 'no way" that he would go 18" deep x 12" wide then make darn sure that the outside edge is graded in a manner to keep the water away from the slab due to the freezing problem you mentioned. He also does not like forming ontop of fill and recommends digging-in footers, but says that it can be done, sometimes with mixed long term results.
I hate going into something this important with such a lack of knowledge, but i assumed that those in the field would know what they are doing....shame on me! It looks like another trip up there to make sure this is done right.....{I Knew i shoulda bought a dozer...and a backhoe...and a......!!!}
Thanks for the info, i apperciate the help!
RD
dmccarty
Super Star Member
RD,
I would want the topsoil removed and no fill dirt if possible just to eliminate the compaction step.
I think you said you had a grade change of 27 inches from one end to the other. Our house floor is a concrete slab 4" thick. From the SW corner of the house to the NE corner there is a grade change of about 60 inches.
The top soil was removed, ain't much topsoil in my area, about an inch or two at most, then the footers where dug which are roughly 12inches deep by 24 inches. CMU and brick on top of the footer to form the wall to hold the fill.
The fill is 67 stone which is supposed to compact to 95%, I think that was the magic number, without compaction. I don't remember how many tons it took but there is lots of it under the house slab. Then the ridgid insulation and the concrete.
I would assme this would work for a garage but I would want a PE to approve it. Our builder is a PE. In 2+ years the house has not moved. We have expansive clay and I was worried about cracks in the dryway around doors and windows. The house is rock solid.
Later,
Dan
I would want the topsoil removed and no fill dirt if possible just to eliminate the compaction step.
I think you said you had a grade change of 27 inches from one end to the other. Our house floor is a concrete slab 4" thick. From the SW corner of the house to the NE corner there is a grade change of about 60 inches.
The top soil was removed, ain't much topsoil in my area, about an inch or two at most, then the footers where dug which are roughly 12inches deep by 24 inches. CMU and brick on top of the footer to form the wall to hold the fill.
The fill is 67 stone which is supposed to compact to 95%, I think that was the magic number, without compaction. I don't remember how many tons it took but there is lots of it under the house slab. Then the ridgid insulation and the concrete.
I would assme this would work for a garage but I would want a PE to approve it. Our builder is a PE. In 2+ years the house has not moved. We have expansive clay and I was worried about cracks in the dryway around doors and windows. The house is rock solid.
Later,
Dan
PAexcavator
Member
MotorSeven,
I did site management on 2 to 6 million dollars construction jobs in the 90's. I agree with "no way" especially if you consider that with your 27" drop, an 8" deep footer won't be on virgin soil (which is normally non-negotiable).
I've been on commercial jobs where engineered fill is used under the floor slab, it's laid down in repeated thin 2"-3" layers and compacted with vibratory rollers and checked for percentage of compaction with proctor tests. With all that, the engineered fill is only good for the floor, footers ALWAYS go down to rest on virgin ground, I've seen them up to 8' deep.
Another way to support a bldg floor is to have holes augered down to solid ground for your base, you can even tie them together under the floor with grade beams (picture holes around the perimeter of your floor with a 12" , or whatever size you need trench connecting them across the floor). Rebar, or sometimes an I beam in the trench will create a reinforced concrete beam under the floor when filled w/concrete. This is probably overkill for your application but I'm just trying to show you how seriously support is considered in commercial construction.
Another technique you can use to stiffen a floor is a haunch, it's similar to, but not as involved as the grade beam. A haunch is just a section of thicker floor, usually running from side to side, typically something like 8" or 12" wide and double the floor thickness.
I'm working on a 4" floor slab for a 24' x 40' garage for my brother now, we're going to pour it monolithic, with a 12" hole augered 36" deep every 8' around the perimeter, rebar in floor on 2' centers with vertical rebar in holes tied into floor rebar. The holes replace a continuous footer and save a substantial amount of concrete, but they are directly under the bearing walls and tied into the floor rebar. Haunches will be placed in an area where he is planning on placing a hoist.
Forming a floor the way I described is more involved than a regular footer, but, using the same (or even less) amount of concrete, can be made much stronger than a traditional continuous footer. Essentially, it's a modified and improved pole building foundation, but instead of a dirt floor, the concrete floor has rebar reinforcements connecting all the holes together.
If you use the holes for your footer you should always put a haunch at the garage doors where equipment is coming on and off the floor. My garage has a 12" x 12" one at the doors.
I did site management on 2 to 6 million dollars construction jobs in the 90's. I agree with "no way" especially if you consider that with your 27" drop, an 8" deep footer won't be on virgin soil (which is normally non-negotiable).
I've been on commercial jobs where engineered fill is used under the floor slab, it's laid down in repeated thin 2"-3" layers and compacted with vibratory rollers and checked for percentage of compaction with proctor tests. With all that, the engineered fill is only good for the floor, footers ALWAYS go down to rest on virgin ground, I've seen them up to 8' deep.
Another way to support a bldg floor is to have holes augered down to solid ground for your base, you can even tie them together under the floor with grade beams (picture holes around the perimeter of your floor with a 12" , or whatever size you need trench connecting them across the floor). Rebar, or sometimes an I beam in the trench will create a reinforced concrete beam under the floor when filled w/concrete. This is probably overkill for your application but I'm just trying to show you how seriously support is considered in commercial construction.
Another technique you can use to stiffen a floor is a haunch, it's similar to, but not as involved as the grade beam. A haunch is just a section of thicker floor, usually running from side to side, typically something like 8" or 12" wide and double the floor thickness.
I'm working on a 4" floor slab for a 24' x 40' garage for my brother now, we're going to pour it monolithic, with a 12" hole augered 36" deep every 8' around the perimeter, rebar in floor on 2' centers with vertical rebar in holes tied into floor rebar. The holes replace a continuous footer and save a substantial amount of concrete, but they are directly under the bearing walls and tied into the floor rebar. Haunches will be placed in an area where he is planning on placing a hoist.
Forming a floor the way I described is more involved than a regular footer, but, using the same (or even less) amount of concrete, can be made much stronger than a traditional continuous footer. Essentially, it's a modified and improved pole building foundation, but instead of a dirt floor, the concrete floor has rebar reinforcements connecting all the holes together.
If you use the holes for your footer you should always put a haunch at the garage doors where equipment is coming on and off the floor. My garage has a 12" x 12" one at the doors.
OP
MotorSeven
Elite Member
Dan and PA,
Thanks, and i like the auger hole idea. The site isin't opitmal, but it is the only place i can put a building in the pasture. This is because my creek seasonably over-flows, flooding the pastures anywhere from 0" to 3'. The site was filled in about 6-7 years ago and is aprox 4' above the pasture. Even at that height the '77 flood would have put this location under a foot or two, so that is why i am trying to get the slab as high as possible. I tried to find the frost line depth for NE TN and ad no luck on the web, but the auger idea would definatly help alot. I'll post some pics of the site when i get back on my own 'puter.
RD
Thanks, and i like the auger hole idea. The site isin't opitmal, but it is the only place i can put a building in the pasture. This is because my creek seasonably over-flows, flooding the pastures anywhere from 0" to 3'. The site was filled in about 6-7 years ago and is aprox 4' above the pasture. Even at that height the '77 flood would have put this location under a foot or two, so that is why i am trying to get the slab as high as possible. I tried to find the frost line depth for NE TN and ad no luck on the web, but the auger idea would definatly help alot. I'll post some pics of the site when i get back on my own 'puter.
RD
dmccarty
Super Star Member
RD,
With that much fill I would hire a PE and make sure that you can build without problems.
If you think the location will flood, have you thought about using materials that are not affected by water or are cheap and easy to replace up to the height of the expected floor. And keep power and other utilities higher in the structure so they would not be touched by flood waters and then have to be replaced.
Later,
Dan
With that much fill I would hire a PE and make sure that you can build without problems.
If you think the location will flood, have you thought about using materials that are not affected by water or are cheap and easy to replace up to the height of the expected floor. And keep power and other utilities higher in the structure so they would not be touched by flood waters and then have to be replaced.
Later,
Dan
OP
MotorSeven
Elite Member
The excavation is done, i augered holes in the perimeter, vapor barrier, wire mesh and plumbing done. The rebar will come on the concrete truck, but i had to get to NO for Turkey day, so i left the rest for my concrete guy. The excavator also installed the 1,000 gal septic tank w/120' of gravelless field line. I was going to do the septic myself, but my excavator put the thing in for what i would have spent on the tank and line alone. Next trip up i will get some pics of the finished slab.
