Foundation site prep

[Tscott9330]

I need to do a little site prep for my new steel building pad. I plan to use my box blade and FEL to scrape off the grass and level it as best I can. The site is basically flat and will not need any fill brought in. Any tips or tricks I need to know?

Tom

 

[JB4310]

I've found the box scraper very efficient at removing sod and leveling ground, unless you have to remove more than 4-6" of top soil, I wouldn't use the loader.
The box is much more forgiving, it may take longer with more passes, but it takes far less skill than the loader for leveling large areas. Use the rippers to cut more and no rippers to just dress up.

If you have to remove more than 6" then get the bulk of it with the loader and dress it up with the box, you will have a huge pile of dirt if you have to remove 6"+ from an area the size of even a small building.

You'll have to experiment with the angle of the box, and it will fill up with turf pretty quick, once it's full you can drag it out of the way, when it's full it doesn't dig anymore.
I've got a new hydraulic top link to adjust angle of box, have not tried it yet but I'm sure it would make box blading easier.

JB.

 

[rimshot]

I need to do a little site prep for my new steel building pad. I plan to use my box blade and FEL to scrape off the grass and level it as best I can. The site is basically flat and will not need any fill brought in. Any tips or tricks I need to know?

Tom

=============

Make sure you have some fall away from your building so you get no water running in from outside. better to be safe than sorry here. What type of soil are you working with? I take it you willl not be pouring a concrete floor. If not you may want to build your floor area up built using crushed gravel.

rimshot

 

[Tscott9330]

Yeah, we will be pouring a full pad for the building. The shop will be 36'x60' all totaled. The area is flat, sandy and compacts well. There should be no need to bring in fill according to 2 concrete guys so far, they say it will compact well and that they can set the pad up an inch or 2 above grade to keep water from flowing if there is any. The ground only has a 2 or 3 inch fall from one side to the other so we should only need to scrape down to get rid of any biological materials. Our property percs very well and we seldom see standing water. I will however slope the ground away from the building just to be sure.

Tom

 

[CurlyDave]

Even if you only scrape a little material from the top, you need to compact the site because there will be a compactible layer of disturbed dirt from the scraping.

 

[Tscott9330]

Even if you only scrape a little material from the top, you need to compact the site because there will be a compactible layer of disturbed dirt from the scraping.

Yep, I definitely agree. Compaction will be part of the job for the concrete crew. I am just doing some of the early work to save some money on the job. I have received a few quotes, and they were pretty high in my opinion. I will just keep doing stuff myself until I get a price i like and then I will let them take it from there.

Tom

 

[rimshot]

Yep, I definitely agree. Compaction will be part of the job for the concrete crew. I am just doing some of the early work to save some money on the job. I have received a few quotes, and they were pretty high in my opinion. I will just keep doing stuff myself until I get a price i like and then I will let them take it from there.

Tom

============

In a perfect world, the best time to pour a pole barn floor is after the roof is sheeted and skirt boards are installed to use as a concrete form. In other words, the basic building is complete less the steel wallsheeting. It's just easier if the side panels are missing for the short time the concrete finishing crew needs to pour concrete with out splashing on steel side panels. In addition the cement finishers can jump in and out and their long handled bullfloats can be used in both directions. But there is even more advantage because not only are you protected from rain but you can do a pretty fair job of keeping the sun off the new floor as well because concrete fresh poured is best if it can cure slowly not just dry quickly.

rimshot

 

[EddieWalker]

I need to do a little site prep for my new steel building pad. I plan to use my box blade and FEL to scrape off the grass and level it as best I can. The site is basically flat and will not need any fill brought in. Any tips or tricks I need to know?

Tom

The steel building will require footings dug to a depth based on your area of the country, the size of the building and the type of soil that you have. Other then clearing the area, there's not allot that you can do yourself if your not going to dig the footings and create the forms.

Getting the area clear, having work areas, parking areas for the crew and storage areas for material will help move things along faster and more easily.

The concrete trucks will need a path to drive in and a place to wash out there tank.

Do you have a septic tank and leach fields? Mark them and make sure nobody drives over them with a cement truck!!!! Do you have anything else that you don't want crushed or destroyed? Mark it and don't be shy about putting a fence around it. Trim your low branches and if needed, wrap your tree trunks if they are in the way.

Good luck, remain flexible and let the experts do their thing without getting in the way.

Eddie

 

[Tscott9330]

Well, I went ahead and scraped the surface clean of all grass with the box blade and then used the loader to scrape a level pad. I say it is level, but I have not pulled a string on it yet but it is more level than it was. It took a few hours, but it was worth it. I got a quote today for the concrete of $8125.00 this is for 44 yds of 3000 PSI mud with fiber added. He is also going to set up the forms and dig the footers to the county specification. Along with 2 loops of #5 rebar continuous around the perimeter. This works out to about $185 a yard. Is this a good price? the first cost I got was $210 a yard which was high. I live in north Florida if that helps.

Tom

 

[EddieWalker]

Concrete work is based on the price per square foot. Prices are regional as each area has it's own conditions that affect what the final price will be. Some places require rebar. The bigger the rebar and the closer together it is, the more the job will cost. It will also make for a stronger slab. Other areas require deeper footings and extensive work on the base before you can even pour. I've done jobs where it cost more to get the dirt to pass inspection then it did to buy the concrete.

I can tell you that here in East Texas, for a basic pad, using #3 or 3/8 rebar on 24 inch centers and a footing around the perimeter, a 4 inch slab is going to run in the $3.50 a sq ft range.

Some people like and swear by fiber in the mix. I don't have any issues with it as an extra to rebar, but the only proven method for strong concrete is with rebar. Wire will work if it could ever be installed properly, but it's almost impossible to do that and I would never allow or use wire for any concrete work. I also wouldn't do a pad or foundation on anything that I wanted for myself or was hired to do for a client with just fiber. I know others have done so and they are happy with the results, but I'm not taking any chances with concrete. It's too important.

Good luck,
Eddie

 

[JB4310]

What I've found when demolishing concrete with fiber in it is a poor quality concrete that breaks fairly easy but stays together a little better due to the fiber.

If you plan on driving anything heavy in there then go to 5" and 3500 psi min. Do the rebar as you mentioned and I would use 6GA 6"x6" wire in the slab. you can skip the fiber, don't know if joints are needed in FL but maybe cut some 10 - 20 ft squares when it's green.

Go for a roller skate finish with industrial cure/sealer, it may be a little slippery when wet but will stay much cleaner and dust free. It's not a bad idea to install some heavy steel eye bolts or equivalent in the concrete to have a secure anchor point to lock things up to with a chain or cable.

JB.

 

[skidoo]

Even if you only scrape a little material from the top, you need to compact the site because there will be a compactible layer of disturbed dirt from the scraping.

Just curious... What if the virgin soil at the desired level is natural gravel? Does compacting do anything?

 

[sixdogs]

What I've found when demolishing concrete with fiber in it is a poor quality concrete that breaks fairly easy but stays together a little better due to the fiber.

If you plan on driving anything heavy in there then go to 5" and 3500 psi min. Do the rebar as you mentioned and I would use 6GA 6"x6" wire in the slab. you can skip the fiber, don't know if joints are needed in FL but maybe cut some 10 - 20 ft squares when it's green.

Go for a roller skate finish with industrial cure/sealer, it may be a little slippery when wet but will stay much cleaner and dust free. It's not a bad idea to install some heavy steel eye bolts or equivalent in the concrete to have a secure anchor point to lock things up to with a chain or cable.

JB.

The thread is older than dirt but the last sentence of the above post makes it worth a repeat. Why didn't I think of this?

Also, you never save any money doing site prep yourself and I've been on lots of jobs to try to fix what saved $18 many years earlier. Rarely can do because buildings, trees, underground stuff and turning radius are in the way.

Do as you wish but grading and site prep are as important as the building itself. Ask around.

 

[kenhar]

There seems to be a lot of misconception about making concrete stronger. The hardness is determined by the mix (3000#, 3500#) etc. The rebar, wire, fiber is to merely hold the concrete together when it cracks. That's why the footing in a building needs to be stronger than the rest of the floor because it supports the outer walls. Naturally speaking, heavy loads on a floor needs heavier reinforcement. Rebar if you plan to drive a vehicle or equipment on it. Fiber if it is mainly foot traffic (patio). Imagine the difference in down pressure of a 200 lb person and a 20,000 lb piece of equipment. Concrete, as hard as it may be, contracts with the seasons. That is why expansions joints are needed in a large slab. The bumps you hear on a bridge is from the expansion joints. When concrete breaks or cracks, the reinforcement is what keeps it from separating. One guarantee about concrete is it is going to crack somewhere.

 

[aircommuter]

You definitely need to compact the subgrade. The you should use 3/4” drain rock 4-6” thick as a capillary break, then cover that with 10 mil plastic and finally 2-4” of sand. Bare minimum of 4” thick concrete with #3 bar on 16” centers. If you plan on a hoist or other heavy use the go up to 6” concrete. If you are planning any electrical or other conduits put them beneath the rock layer and fill with sand.

 

[jigs_n_fixtures]

OK, most of what I have read so far in this thread scares me.

Standard plans for a residential driveway are typically 4-inches of 3500-psi concrete, over 4-inches of of “road base” gravel, compacted to 90% of the Proctor theoretical, and 1/4-inch welded wire mesh at 6-inch spacing, embedded at mid slab (it needs to be in the middle third of the slab to work.

Standard plan for a commercial driveway, is 6-inches of 4500-psi concrete, over 6-inches of “road base’ gravel at 95% of the Proctor theoretical, with #4 (12-mm) rebar 12-inches on center, both ways. Again it needs to be mid-slab to work.

This will vary based on local soils, but will generally work any where.

At the level of cost you’re headed towards with a building that size, I highly recommend that you get a Licensed Engineer at this point, before you get too far into things.

Most building departments require, sealed Engineering Specs and Drawings for buildings this size, and the building manufacturer probably has an Engineer they deal with fairly regularly, who they can recommend.

If I were doing this building for me, the slab would be at least two placements, in a checkerboard pattern 10X10-ft segments, using lost metal forms, and slip dowels between the slabs. With the metal forms at 10-foot on center, it is very easy to rest the 12-foot screed on the tops of the forms, and get a very smooth level surface. Plus 6-inch concrete wants to crack at about 12-ft on center, so the shrinkage cracking will occur at the forms and not in the slab. Locally we have issues with radon, and require gas barriers. So I’d place a bonded and reinforced barrier of two ten-mil thick polyethylene sheeting on top of the gravel. This would also help ensure there would be no cracking in the slab segments.

 

[jigs_n_fixtures]

Just curious... What if the virgin soil at the desired level is natural gravel? Does compacting do anything?

Depends on the gravel, and how much it got fluffed by the grading. Most alluvial gravels will get firmer with compaction because the rock is rounded and smooth. Highly granular talus materials with benefit less, but still benefit some form compaction.

 

[aircommuter]

Standard soils engineering plans call for minimum 90% compaction 12” deep on sub grade native soils. Personally I like #3 bar on 16” centers instead of 6x6 wire because it gets walked on so much during placement. With the larger space they can step inside. Side note about price, I just added some walkways and the price of just the concrete, 9 yards on the truck was $196.00 per yard. Of course this is California for you. I have used a little over 450 cubic yards on my property.

 

[Flogger]

I was 6" above grade at my highest point. Wish it would have been 8 or 10".

 

[aircommuter]

I usually setup for 12” above grade with the finished floor. I also put a 3/4”x 10” drop at the big door entrances. Then water hitting the door goes out instead of ponding and migrating in.