Planet 67 gets under way...

[67HEAVEN]

Yes, John and Mac. My local building supply has plenty of Owens-Corning Celfort in stock. However, they come in 2' x 8' sheets. I'm considering the 2" thick variety that offers a R10 rating and is good for 20 lbs/sq.in. So, now I'm wondering what the weight of a 6" thick slab and a full-size Tahoe on a lift is per square inch. :W

http://www.owenscorning.com/worldwide/canada/HowTo.asp?HowToID=12&Language=1

Comments?

 

[Mac]

Comments?

Once the slab is set up, the weight of your Tahoe and your lift will be spread over a very large area... essentially, the entire slab... so factor that into your PSI calculation.

I was reading recently that foil-faced insulation materials do not perform as well as products like Celfort. Here's a link... click!!

-Mac

 

[67HEAVEN]

I was reading recently that foil-faced insulation materials do not perform as well as products like Celfort. Here's a link... click!!

-Mac

Thanks, Mac. That gives me a warm and fuzzy about Celfort.

Yesterday, I recycled the plastic and the wood from the footing forms and covered the top of the block to keep the rain from getting in. Water and below freezing temperatures does nasty things to concrete.

Next, I backfilled the first two courses on both sides. In a few days, I'll move up another couple of blocks. I'll soon be ready to call for gravel.

 

[Scott Winebarger]

My builder used agricultural lime for backfill instead of gravel saying it is something like 98% packed when it goes down. He says thats what everyone uses here for backfill before pouring concrete. A little water on it and it sets up hard as rock. I have never heard of using it myself. I have as much as 6 ft deep of it on the lower side, so I guess time will tell.

 

[67HEAVEN]

My builder used agricultural lime for backfill instead of gravel saying it is something like 98% packed when it goes down.

You're right. I shouldn't have typed gravel. I meant the same stuff that I used on the drive......3/4 cusher stone.

 

[67HEAVEN]

So, once again I turn to the experts on CAC for some confirmation (or denouncement) of my next steps.

When the back-filling with sand is complete, around the perimeter, I plan to:

1. fill the inside of the building with 3/4 crusher stone up to approximately 9" below floor level;

2. we'll then ensure the most level floor possible by adding an inch or two of sand, bringing the level to exactly one block (8") below the top of the floor;

3. we'll lay down a 10-mil vapour barrier;

4. we'll lay down 2" thick sheets of Celfort (discussed in posts above), taping the sheets together;

5. we'll pour a 6" slab of 25MPa concrete;

6. we'll spray on a clear concrete sealer the day after the pour.

There is, however, a step missing..........the rebar. In the last garage project I built, the rebar bundles were run across the garage floor in two trenches dug in the stone, from one side to the other, just prior to the pour. Therefore, the rebar bundles got saturated with concrete and became one with the floor.

If I have a vapour barrier and the Celfort sheets on top of the stone, how do I incorporate rebar in the concrete pour on top of the Celfort? :confused

I know you guys will have the answer.

 

[Dirtfarmer]

We lay the steel on dobies on top of the vapor barrier. The dobies have wires embedded in them so you can tie them in place. I've used busted up pieces of block/brick in place of dobies but they don't stay in place as well if the steel is disturbed during the pour.

I've got no experience with Celfort.

 

[Mac]

I've never heard of dobies but I was going to suggest something similar. Go to the same place you bought your concrete blocks and get some pier blocks. They're often used under decks and available in a variety of tops including one which allows you to rest rebar into them. The canted shape means they'll sit nicely on the Celfort and the shaped top should make rebar pretty easy... They're sometimes called four-way deck blocks.

Here's some pier blocks being used for decking. I wish I could find a better picture but you get the idea?

-Mac

 

[67HEAVEN]

Dirtfarmer and Mac,

Thanks for the photos and suggestions. My concern is the height. I'm planning a 6" thick slab and I'm not sure that would completely cover either method.

Keep in mind, I'm creating a sealed base (taped joints) of Celfort sheets, with rebar on top of that. If I attempt to submerge the dobies or pier blocks between the sheets (to drop the height of the rebar down), I've lost the barrier to heat loss and dampness that the Celfort is helping defeat.

I'm guessing that I'd have to pour a 8" or 10" slab to cover the rebar unless I place it on small pieces of broken brick, etc. As mentioned earlier, however, that would be problematic during the pour as we'd likely knock the rebar off. :confused

I may have thought of a solution, but I'd be interested in hearing other ideas first.

 

[68Roadster]

Chairs?

Will rebar chairs not work? They are available in many sizes....

 

[Dirtfarmer]

Mac has a good idea. Talk to the guys that you bought the block from. They should be able to tell you what you need or at least point you in the direction of a local pro.

Dobies are made for this and with a 6" pour would give you plenty of room. They are small enough(1.5 -2 inches) to stay well below a 6" pour and would actually put your steel right below the middle of the slab. When we use dobies on a slab, we actually reach into the mud and pull up on the steel to center it and get concrete under the dobies.

Pier blocks are too tall (6-8 inches).


The point of all of this is to use stone to keep your steel off the ground. Steel touching soil (sand, gravel, etc) or air equals rust. You don't want that in your floor. I would take all precautions, even with the insulation and vapor barrier.


The rebar chairs look interesting but I wonder if those are used when pouring on top of concrete (cold joint). I dont't know what the chairs are made of but I wouldn't want any plastic or steel bits that were in contact with the ground touching my rebar.

 

[68Roadster]

The rebar chairs look interesting but I wonder if those are used when pouring on top of concrete (cold joint). I dont't know what the chairs are made of but I wouldn't want any plastic or steel bits that were in contact with the ground touching my rebar.

Dirt,
The rebar chairs are used extensively here, on top of soil or vapor barriered slabs, walkways, patios, etc....
In my case I used them for the garage floor slab and driveway. The thickness was around 4 - 5" and the chairs kept the rebar at 2-1/4. They are plastic.
Preferred them over using broken bricks.

 

[Toms007]

Bob, I have never poured concrete over the rigid insulation, so I can't offer any suggestions. But it appears that you may have your answer.

 

[Dirtfarmer]

Dirt,
The rebar chairs are used extensively here, on top of soil or vapor barriered slabs, walkways, patios, etc....
In my case I used them for the garage floor slab and driveway. The thickness was around 4 - 5" and the chairs kept the rebar at 2-1/4. They are plastic.
Preferred them over using broken bricks.

You and your fancy rebar chairs. :L

Thanks for the info.

 

[JohnZ]

We used the 2" plastic rebar chairs (sitting on my foil-faced foam sheets) to support the steel mesh panels in my slab; seven years, not a single crack; slab was saw-cut in 8-foot squares for crack control, but no cracks.

 

[67HEAVEN]

Will rebar chairs not work? They are available in many sizes....

Thanks for that photo. Very helpful.

When we use dobies on a slab, we actually reach into the mud and pull up on the steel to center it and get concrete under the dobies.

I visited one of my major clients yesterday, and talked to their on-staff building designer. He suggested a combination of your idea and John's steel mesh.

We used the 2" plastic rebar chairs (sitting on my foil-faced foam sheets) to support the steel mesh panels in my slab;

John, the guy mentioned above suggested that I use welded wire mesh (6" x 6" in rolls) rather than rebar. They lay it out and lift it up into the fresh concrete as the pour proceeds.

NOTE: I appreciate all the advice given. Together, we'll get this baby built.

 

[67HEAVEN]

Here's a great page on "parging" concrete block.

http://www.backwoodshome.com/articles/leonard57.html

 

[Dirtfarmer]

Wow, flashback man.

We used to use something similar to that in the 70's and 80's. It was my job (I was a kid back then) to roll out the wire mesh and cut it to size. I don't know if it's the same stuff that we used but it looked like heavy fencing material.


If it's the same stuff we used, when you roll that stuff out, it's going to want to roll itself back up behind you. Stick a 4-5 foot long 2X4 through one of the squares to keep the cut end from curling up on you.

 

[Toms007]

Is that stuff still being used? OK, if it still passes code it works pretty well. Just make sure it is up in the middle of the floor and not pressed down to the bottom. We used to have a "hook" that we would use to grab the mesh through the concrete and pull it up into the center of the thickness of the floor. When you are walking around in the mass of flowing concrete it's easy to push the mesh clear down to the bottom where it won't do much (if any) good.

 

[67HEAVEN]

There's a construction project out there somewhere. :W