In normal dirt, there's no point to using plywood aside from making
the *TOP* neat to see. Underground, concrete on undisturbed earth is
best.
Some soils are so crumbly that the hole won't keep its shape no matter
what you do. That is a special situation that needs a method approved
by a local PE who knows the soil types, no matter what the factory
specs are.
Otherwise, if all you're trying to do is save a few bucks and use less
concrete than a hole larger than need be, DON'T.
If you do it anyway, REMOVE the plywood once the pour has hardened.
The earth around the base MUST be power-tamped in small layers to the
point it is as compacted as the original undisturbed earth.
If you are doing it in an area where much of the dirt was fill in the
last 5-10 years, you should power-tamp it anyway.
Personally, I like bases dug and poured in original undisturbed
clay-based hard pan. Immovable.
73 and good luck,
Guy, K2AV
----- Original Message -----
From: "Jim White, K4OJ" <k4oj@tampabay.rr.com>
To: "EUGENE SMAR" <ersmar@comcast.net>
Cc: <towertalk@contesting.com>; "Rich Hallman - N7TR" <rich@n7tr.com>
Sent: Sunday, June 29, 2003 8:44 PM
Subject: Re: [TowerTalk] Using plywood forms...??
> Gene...
>
> Are you saying the 1/2" or 3/4" of plywood around the pour once it
> disintegrates will create a void that wide between the earth and the
> pour???? And then the concrete mass could shit by 1/2" or 3/4"
>
> I seriously doubt that... and think nature wouldfind a way to make
up
> for the "slack" as rains came and went the soil would ultimately be
> found near the pour...
>
> Jim, K4OJ
>
>
>
>
> EUGENE SMAR wrote:
> > Rich:
> >
> > Absolutely remove the form. If you don't, when the wood
decays, that
> > side of the foundation will not have the support from undisturbed
earth that
> > the other sides have.
> >
> > This means that you'll have to allow sufficient room around
the
> > foundation to get at the wood for removal. That, in turn, means
you'll have
> > to backfill the void. And finally, that means you'll have to
compact the
> > backfill as it's being dumped into the excavation. Don't just
shovel in the
> > dirt and walk away. After each half a foot or so has been
shoveled in,
> > punch at it with the end of a 2X4 until it doesn't compress any
more. Then
> > shovel in the next half a foot, etc.
> >
> > However, it might be easier if you just fill in the oversized
hole with
> > a bit more concrete. You'll avoid the need to worry about forms,
removal,
> > compaction, etc. The hassle is a toss-up between excavating
exactly the
> > right sized hole vs buying and placing a bit more concrete.
> >
> > 73 de
> > Gene Smar AD3F
> >
> > ----- Original Message -----
> > From: "Rich Hallman - N7TR" <rich@n7tr.com>
> > To: <towertalk@contesting.com>
> > Sent: Sunday, June 29, 2003 3:11 PM
> > Subject: [TowerTalk] Using plywood forms...??
> >
> >
> >
> >>I'm installing several Trylon T400-80's. I noticed that you can
use
> >
> > plywood
> >
> >>forms for those times when your backhoe guy gets carried away with
the
> >
> > hole
> >
> >>digging.
> >>
> >>If I use a form for one end of my oversized base.....Do you remove
the
> >>plywood, then backfill.....Or backfill with the plywood in place?
> >>
> >>Thanks...
> >>Rich
> >>
> >>www.n7tr.com
> >>
> >>_______________________________________________
> >>
> >>See: http://www.mscomputer.com for "Self Supporting Towers",
"Wireless
> >
> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041
with any
> > questions and ask for Sherman, W2FLA.
> >
> >>_______________________________________________
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> >>TowerTalk@contesting.com
> >>http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers",
"Wireless Weather Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers",
"Wireless Weather Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
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