32" build in north TX HardieBacker board

[strobes]

My stand is 60"x64", but I want to make the top about 4" wider and longer on each side, 3.5" thick, reinforced, poured on top of HardieBacker Cement Backerboard.
Do I need to build support for the 4" of the board that extends outside of the cement blocks? Or the board is strong enough to support the weight of the wet concrete?
I estimated that the board should support about 78lb of concrete. ( 4"x3.5"x64"x 150lb/cubic ft)

[thebigt]

Re: 32" build in north TX HardieBacker board

My stand is 60"x64", but I want to make the top about 4" wider and longer on each side, 3.5" thick, reinforced, poured on top of HardieBacker Cement Backerboard.
Do I need to build support for the 4" of the board that extends outside of the cement blocks? Or the board is strong enough to support the weight of the wet concrete?
I estimated that the board should support about 78lb of concrete. ( 4"x3.5"x64"x 150lb/cubic ft)

Are you pouring a new slab overtop?

I built my original top slab smaller than I needed and it required wood forms to be built around the slab with supports going to the ground and I had to pour a new 4" thick slab over top of my old one.

It may also be easier to keep all of your questions in a single thread rather than starting different ones for each question.

[Les]

Re: 32" build in north TX HardieBacker board

You must already have forms for the pour on the edge, just incorporate some vertical support as well. Something cheap and dirty as as 2x4's every 3 or 4 feet.

[thebigt]

Re: 32" build in north TX HardieBacker board

When I was doing my build Gulf(a member on the forum) drew up some pictures for me to help me visualize my concrete forms to extend out my existing form. they can be found here http://www.fornobravo.com/forum/2/ov...e-20428-5.html