Eric,
Standard caveat. I am in the pre-engineered building business, and have
an interest in selling you a building. Now, moving on,
Assuming that the existing slab is fairly solid, no reason to remove.
Assuming your usage to be mostly light duty, there is no reason to dig
out an excellent subsurface to replace it with stone and pour again other
than an elevation change. Two ways to proceed:
1. Sweep off the existing to remove loose crap, form the edges, cover
with heavy mil visqueen, pour at least 4" new concrete with fiber
reinforcing (wire is optional). This gives you a floating slab on top
of the original.
2. Sweep off the original, then water blast to remove all loose stuff.
Allow to thoroughly dry and form the edges. Apply a coat of concrete
bonding agent according to directions. Pour somewhere arond 1.5"/2" of a
very high strength pea gravel mixture with fiber. This gives a bonded
slab, but counts on the integrity of the existing slab. Cracks in the
original will migrate upward eventually, even if forced into preplanned
control joints.
In either of the above cases, concrete thickness is the minimum from the
highest elevation of the existing.
Send me an address and I will send you literature on buildings. You need
to decide on a building before slab repair as different frame designs may
require foundation preparation prior to slab completion.
GPD4
On Wed, 6 Dec 2000 08:20:39 -0800 Eric Murray <ericm@lne.com> writes:
>
> My place was a working farm of some sort at the turn of the century.
> We're currently restoring the barn whose foundation had cracked
> along
> one side. The old concrete was easy to break up- it was cement and
> sand, no gravel, and the concrete has softened a little in some
> places
> or wasn't all that 'rich' a mixture to begin with.
>
> Behind the barn is a foundation and slab that's about 32'x32'. I
> scraped
> off most of about 80 years of leaves and soil that was on it this
> last weekend. It looks like it's got a pretty good foundation
> around
> the outside of the slab, but some of the the concrete in the middle
> is
> crap- you can dig into it with a shovel. Some other parts look
> good,
> but are uneven. It looks like it was poured in small sections and
> at
> different times. I don't think that it's settled or cracked. It's
> on a
> flat carved out of a slope, with a small retaining wall on one side
> and
> part of the back, and a slope falling away from it on the other
> side.
> It's also about 2' taller than the ground behind the barn, with a
> dirt
> ramp leading up to it.
>
> I'd like to build a shop there. It's the best spot I've got unless
> I
> want to bring in a D9 and move a few hundred cubic yards of
> overburden.
> I was thinking of just putting up a metal building, since it's
> hidden behind the barn I don't really care if it's not all that
> pretty
> on the exterior, but I'd like it nice inside.
> There's enough room to put in a driveway around the barn to get to
> the shop.
>
>
> Ascii art:
>
>
> 4' retaining wall
> |
> v
> --------..........
> | . -> steep downhill
> | .
> | . ->
> | .
> | slab . -> steep downhill
> | .
> ->| . ->
> | ...................
> | ssssssssssssssssss <- 2' slope
> |
> |
> |
> | flat area
> |
> |
> |
> retaining wall (1' here, 4' in corner)
>
> -------------------------
> | | r
> | | o
> | | a
> | barn | d
>
>
> The slab isn't good enough for a shop- too uneven and too crumbly in
> spots.
>
>
> So, here's the questions (you knew this was coming): Can I
> pour a new slab over the old one? Is that to code? How do I
> find out what code is?
>
> Also, how much space should I leave around the metal building on
> each side?
> If I want a 3' walkway on both sides, that'll leave 26' in width.
> That's ok, but I'd like wider.
>
> The garage floor being 2' higher than the driveway will be a bit of
> a
> problem for low-slung cars (but not for bikes, other than needing a
> bit
> of momentum to push a bigger bike up the slope). I'll probably work
> on cars some but mostly on bikes, but I'd like it to appeal to car
> people
> also for when (if) we sell the place. Should I just spend the extra
> $$
> to have the old slab/foundation ripped out and make it level with
> the
> driveway? (and build new higher retaining walls) Given that I live
> just outside Silicon Valley where construction labor is 2-3x what it
> is in the rest of the country?
>
> Finally, any recommendations for metal buildings which can be
> insulated
> and finished nicely inside would be appreciated.
>
> Thanks for reading this far!
>
> --
> Eric Murray Consulting Security Architect
> SecureDesign LLC
> http://www.securedesignllc.com PGP
> keyid:E03F65E5
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