Replies

1. 
   PeterM_ | Jan 14, 2000 07:55am | #2

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   You could also run 2 X s across the existing slab if there is an existing wall nearby.
   I have had excellent result lining the inside of the forms with clear mailing tape [2" wide (from stationary store)]. The concrete doesn't stick to it, you can easily remove it and the boards are as clean as new, and it leaves a very nice, smooth surface if you vubrate it well.

2. 
   Guest_ | Jan 15, 2000 01:30am | #3

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   Here's what we did.

   tied the form together with wire so it couldn't spread and laid the form on the concrete.

   I piled alittle dirt along the side of the form last night and this morning when it was time to pour, it was 17° outside. That pile of dirt had frozen harder than the slap itself. That form won't move. Couldn't have gotten luckier.

1. 
   Guest_ | Jan 15, 2000 11:08am | #4

   *RyanIts always a great day when Mother Nature is on the crew :)Scott

1. 
   Guest_ | Jan 16, 2000 06:17pm | #6

   *Ryan,Is it that you do not want to have to patch any holes in the slab? Tie wire fastened back to existing slab inside the formwork. Coil ties can be easily fabricated to length;superstrong;only a small hole to patch after removal of lag bolt. When drilling holes in slab is not an issue, a 2x4 drilled thru w1/4" percussion bit will easily accept 2 16d doubleheads to secure bracing. This system also strips easily. Dealing with form uplift is always a personal choice.Food for thought, Rick

3. 
   Guest_ | Jan 16, 2000 06:17pm | #5

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   I've cut an opening in a concrete slab, excavated to 3' and will be pouring a raised concrete pad that will sit a foot higher than the slab surrounding it.

   I've got a form laid on top of the hole and all I've done to secure it is pile dirt around the form. I'll probably be okay but I'm wondering how you've handled this.

   I really don't want to drill the slab for pins.

   -Ryan

1. 
   Guest_ | Jan 14, 2000 06:43am | #1

   *RyanLooks like a machinery foundation. We usually drill holes through the forms and run several lengths of 3/8" or 1/2" all-thread from one side to the other, and one or two end to end, with nuts and washers on the outside of the form. This keeps everything from spreading, without needing to fasten it to the existing floor. Tie wire the all-thread to some of your rebar at convienent places and it should stay put. To strip the forms we cut the all-thread off with a sawz-all or a 4 1/2 inch grinder. After the forms are off, we just grind the protruding all-thread off flush.Scott