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-   -   A Question about Re-Bar & Polymers (http://www.diychatroom.com/f105/question-about-re-bar-polymers-154216/)

BeachBum2 08-19-2012 03:38 PM

A Question about Re-Bar & Polymers
 
I am removing a 17' section of a CMU wall. We are taking it down to the foundation. I will install a steel beam system, attached to the foundation and them I will build the foundation back up approx 3.5". On top of this 3.5" build I will install a large heavy sliding glass door system...

How much horizontal re-bar should I put into this 3.5" x 17' space?

How many bolts should I roto-hammer into the existing foundation to act as grippers to the new pour?

Should I "attach" the horizontal re-bar to the bolts?

Is it advisable to add a polymer to the concrete pour, so it "sticks" to the existing foundation better?

Anything I missed?

Thanks very much!

TRUEPRO 08-19-2012 06:25 PM

First off, for any project involving structural modification there should be an approved drawling. This drawling would be submitted to the city for approval so a permit can be pulled. If this is not a project that will be conducted under these guidelines, perhaps a picture would help to get a better idea. Im almost right there with ya on what exactly your doing but i need a little bit more...

BeachBum2 08-19-2012 06:57 PM

Visualize a 20' X 8" top of foundation....

I need to make the foundation 3.5" taller.

I will put a form to the front of the foundation to hold the wet mix.

To insure that the wet mix does not crack or separate from the old existing foundation, I need to run re-bar and drill bolts into the existing foundation. When the new concrete is poured onto the re-bar and bolts, it "should" hold - Forever I hope.

So my questions are -
How many bolts?
What type of spacing and pattern between the bolts?
How much re-bar and where within the 3.5" should the re-bar be placed?
Should I add polymers to help the new concrete stick/adhere to the existing foundation?

Thanks very much.

TRUEPRO 08-19-2012 11:23 PM

Again, i wouldnt recommend doing any of this without professional approval of what your trying to do here.

What is the "steel beam" system you are referring to?

Will you be using treated lumber for your bottom plate?

The bolts you are planning to use should be drilled 4-5" into the original footer. Normally rebar would be used to attach a new foundation to existing horizontally but i will assume the bolts are for the bottom plate.

2 part epoxy shall be used to secure the bolts. Space them out every 32".

Ill assume your making the concrete yourself. Find a fiber additive for the concrete to increase strength.

As far as rebar in the in new pour.... 3.5" x 8" is no where near enough area to use rebar. You could put a few pieces of ladder wire in it. Connect the wire to the bolts using wire ties and wire tie twister. The bolts coming up will be plenty of support.

BeachBum2 08-19-2012 11:43 PM

I will respond to your post, below in red:

What is the "steel beam" system you are referring to?
After I remove the 20' space of existing CMU wall, I have to support the roof above. I only have space for a steel beam & post system that I had designed by an engineer.

Will you be using treated lumber for your bottom plate?
My "bottom plate will be concrete... the 3.5" deep x 8" wide x 20' long "pour" that I have been talking about.

The bolts you are planning to use should be drilled 4-5" into the original footer. Normally rebar would be used to attach a new foundation to existing horizontally but i will assume the bolts are for the bottom plate. There will be no "bottom plate". I am making the "foundation" 3.5" "taller", and my threshold will sit on top of it. The bolts I was talking about would be used to help secure the new 3.5" pour to the old / existing foundation. I can drill them into the old / existing foundation 4-5" for the bolts, or pieces of cut re-bar... no problem. How much re-bar should be exposed (above the existing foundation)?

2 part epoxy shall be used to secure the bolts. Space them out every 32". Ok, can do. Again - how much should stick up / out of the existing foundation?

Ill assume your making the concrete yourself. Find a fiber additive for the concrete to increase strength. I will mix it, but I really don't like to use fiber, as it makes a fuzzy mess. What about a poly additive - to help adhere it to the existing foundation?

As far as rebar in the in new pour.... 3.5" x 8" is no where near enough area to use rebar. You could put a few pieces of ladder wire in it. Connect the wire to the bolts using wire ties and wire tie twister. The bolts coming up will be plenty of support. I was speaking about re-bar running the 20' length, within the 3.5" deep & 8" wide pour... Should I use re-bar in this long pour?

Thanks!


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