Your experience is slightly different from mine. I just poured the same
foundation but it ended up 6 x 6 x 7 and framed out 6 feet on the top with a
six inch border and it took 10 yards of cement to fill it. The first three
feet were real earth and the rest of it was basically sand. The cage is
supported properly and underneath it probably is more barrel shaped rather
than square because of the sand movement. But it is not ever going any
place any time soon. As far as I am concerned, the extra cement is my sleep
factor. And as far as going to all that problems of forming it and putting
the dirt back in and all the rest of it, the costs probably works out about
the same, but with a little extra concrete. I am now awaiting for 28 days
to pass so I can bolt my tower to it and hopefully I can get on the air
before winter sets in here in the East. 73's Gene K2QWD (Almost there!)
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Alan NV8A
Sent: Tuesday, October 24, 2006 11:11 PM
To: towertalk reflector
Subject: [TowerTalk] Foundation progress report -- and thoughts
on"professionals"
The contractor came on Saturday and started digging the 5' x 5' x 7'
hole for the foundation for my US Tower HDX-555. He used an oversized
post-hole-digging attachment on a Bobcat, then squared it out by hand,
but ended up with a hole that is more like 9' x 8' at the top.
By the time he came back Monday, the hole was half-full of water after
heavy rain and he didn't have a pump with him, but he went ahead and
built a frame for a 7' x 7' top, but with the top surface 10" above
grade (because he had brought 10" wide boards) instead of the maximum 8"
specified on the drawing; I had him dig out under the ends of his
framing so that the top would be less than 8" above grade. He was then
about to construct a plywood template for the mounting bolts instead of
using the base plate itself as described in the docs. I had given him.
He was to come back Tuesday to do the rebar cage (but canceled), but I
had already asked him how he was going to support the cage at the
specified 3" above the bottom of the hole. He replied that he was
planning to drive the rebar down into the dirt at the bottom of the
hole!!! When I pointed out that this was contrary to the engineering
drawing and was, moreover, according to everything I have read, an
absolute no-no (as discussed here recently), he said he would put bricks
under the bottom of the vertical bars to support them.
This guy is supposed to be a "professional" (he normally builds
supermarkets and the like, but the construction business and the economy
in general are a little slow around here these days -- too many
businesses dependent on the US auto industry), yet it seems that he does
things "by guess and by golly." I'm glad I was around to keep an eye on
things. Based on this and other experiences, I often wonder whether
"professional" sometimes just means a person who does a particular kind
of work for a living but as cheaply and as quickly as possible?
We may have below-freezing temperatures Wednesday, but he's planning to
set the base plate and bolts in place then and pour concrete Thursday or
Friday. In the meantime I'll be putting in place the conduits and
electrical box for the lightning protection devices.
BTW, he hit clay about 1ft. from the bottom of the hole. Does that
indicate that the the foundation should be constructed differently?
AIUI, although clay is difficult to dig it doesn't provide much support.
Alan NV8A
Zeeland, MI
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