Homeowner Forum / Construction / November 2005

Since the footer is usually below grade (how much depends on the frost line)
and the slab is at grade I don't see an advantage to pouring both at once
unless it is economic.  The perimiter wall serves as the form for the slab
making for less labor and materials even if it has to be done on different
days (unless the concrete delivery charge is very high due to a remote
location)

As for block or poured wall, so long as the load is downward the choice can
be made entirely on budget (materials and labor, which method is lower).
Again, the concrete delivery charge might be the tipping point for you.  I
could DIY a block wall but not a poured one.  If you pour the slab before
building a block wall, you save a trip on concrete delivery but you will not
get as good a bond between the wall and slab.  This could allow water
intrusion if the water table rises.  And if the form for the slab shifts or
is not square, the walls will be harder to build

If I were to DIY this I would look for precast footer blocks (if they exist,
I am not sure) and build a block wall then order the concrete slab.  If your
in Phoenix or Tuscon you don't need to worry about freezing but in Flagstaff
you need a better footer.

James,

That's the approach I used.

I used 2x6's and 2x8's to form the footings, installed #4 rebar, and
poured the concrete.

A week later, I built forms out of 3/4" plywood and a 2x4 framework. Each
plywood sheet produced two 2x8 foot forms. Anchored them to the footing,
tied them together top and bottom, install #4 rebar and anchor bolts,
oiled the forms inside, and poured the concrete.

Another week later, I stripped the wall forms, then brought in gravel and
compacted it down over a layer of 6 mil plastic. I hired out the actual
pouring of the slab. That needed more manpower and experience than I
could do on my own.

It's more complicated and expensive than a simple slab, but it has many
advantages. The exterior wood is elevated 1 to 1-1/2 feet above the
ground to minimize splashback damage and rot. And you gain an extra 1-1/2
feet of headroom inside. The monolithic pour is stronger than block, more
resistant to seismic movement, and less likely to leak (no joints).

The footing forms can be cleaned up and reused. Many of ours became studs
or blocking in the rest of the building.

You can rent the wall forms, but we were reusing ours a few times for our
house foundation. So we preferred to build our own forms. We later used
them to build scaffolding, and finally sold them to a farmer who was
going to build small buildings from them.

Anthony