Dear OMs,
My project is to erect a self supporting tower i bought a few monthes
ago. The tower is 13 meters (36 ft) high and weights around 250 Kg. I
planned to dig a square hole of 4x4x4 (based on what i read about
similar towers), to put a rebar cage and a tower base into it, and to
pour the concrete.
However, reality differs from my plans, and i have a few questions.
Please note that the tower has been "home made" (not by myself). I am
confident in it but i can't simply "ask the tower manufacturer" my
questions about the foundations. That's why i need your help.
I asked one of my neighbour if he could dig the hole (he has machines
for it). He accepted, and i explained him what i wanted. Unfortunately,
he came one day with his machine while i wasn't here and dig (dug?) a
hole that wasn't deep enough (just 2 ft). When he came back to check if
that was OK, i told him that i needed twice that depth. He came back
another day while i wasn't here (really bad luck) and dug again... i
ended with a hole that is now too big ! It's now 5x6 and of 7 ft depth.
My first question is about the foundations dimensions. What do you think
about them ? Does 4x4x4 seem sufficient to you, or should i keep 5x6x7 ?
(of course, i could keep the big one as a "safety margin", but if 4x4x4
is already safe, i see no interest in paying the additionnal concrete it
will take to fill the big hole).
If a want a smaller hole, i can simply put back some ground (?) into it
for less depth, but i can i do for a smaller "area" ? I could build a
wood frame for the dimensions i want, put it into the hole, and put some
ground around it, but i wonder if it will be sufficient, because when
i'll pour concrete in the frame, it will have a great pressure from
inside to outside.
About the top of the concrete base: Usually, the concrete base is higher
than ground level. What's the reason for this ? I would like better to
have it lower than ground level. That way, i could have just the tower
base coming upside. In my garden, 5x6 of grass would be nicer than 5x6
of concrete. Of course, rust on the tower base would be a concern, but
if it's the only reason, i feel i can deal with it.
About the tower base (to be sealed in the concrete). How deep should it
go into the concrete ?
Thanks for your help ( and sorry for my bad english)
--
Laurent F1JKJ
_______________________________________________
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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