[TowerTalk] Help with PE certification of tower in NJ

Sat Nov 19 20:20:23 EST 2005

Hi Folks!
This exchange has me thinking.
When 8 foot, C-band dishes started popping up on homes, there were mounts
that did not have drilled and bolted bases.  I'm wondering if they make
sense, or if drilled and bolted mounts through the eaves and joists of my
home make sense?

I'm not going to put up a C-band dish (which is typically aimed up at an
angle), but I am thinking about either a four or six foot dish for 1296 and
2304.  I could use one of these C-band dish mounts.  

Alternatively, I could use my 3-1/2 diameter (1/4 inch wall) rotatable mast
which goes through two bearings tied to the ceiling joists and the internal
walls (it's mounted in a corner of two walls) of my office.  The rotator is
mounted on the floor.  The two bearings are 18 inches and 60 inches below
the roof and the mast extends up to eight feet above the roof.  

I haven't decided which to use, but your thoughts would be appreciated.
73,
Gordon Beattie
201.314.6964
w2ttt at arrl.net

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Hank Lonberg
Sent: Saturday, 19 November, 2005 12:08
To: 'Bob A. Booey'
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Help with PE certification of tower in NJ

Bob:

Well I bet that they want a letter and calculations to back up the statement
of load capacity. 

110 mph is not unusual near the coast. This is the IBC wind velocity which
is a 3-sec gust value.

Different states have different requirements for the PE stamp. The states of
NJ and FL require an embosser which makes the raised seal like a notary.
Most states just require an inked stamp.

No difference between sealed engineering calculations and sealed
calculations, I was looking to minimize typing.

Well, with the bottom in a concrete base and guyed at 50'
plus or minus, your tower and base should be adequate for the antenna
loading you describe. I'm a little concerned about the guy which is
terminated at the roof.  The guy can develop well over a 1000# of tension
force at the anchor point.

Yes, I can provide the engineering services once you determine what the
township needs. The discussion of fee will be conducted off list, as it is a
private discussion between you the client and me the engineer.

If you wish use someone local; I suggest you go to the ARRL website and look
up the VCE page (volunteer consulting engineers). I am registered on the
list but there maybe someone local which may make the process more
convenient for you.

Regards

Lonberg Design Group, Ltd.

Hank Lonberg, P.E., S.E. / KR7X
President

-----Original Message-----
From: Bob A. Booey [mailto:rentwist at comcast.net]
Sent: Saturday, November 19, 2005 7:09 AM
To: Hank Lonberg
Cc: Entwistle, Robert Jr RDECOM CERDEC I2WD DHPC
Subject: Re: [TowerTalk] Help with PE certification of tower in NJ

Hank,

Thank you for your reply.  The township did not spell out exactly what was
required from the PE, although as I recall I think they just wanted a letter
certifying the design to meet 110 MPH wind load with perhaps a raised seal
(do PE's have stamps similar to Notaries?).  What is the difference between
seal engineering calculations and sealed calculations?  I don't know and I
am pretty sure they won't know, but I will ask.  I will call Monday and get
clarification.

As for what I have, the answer to both of your questions is yes.  The bottom
4 feet of the first 10 foot section is embedded in a concrete base which is
poured into the ground 4 feet, gravel below, close to the side of my house
(positioned to place the tower at the right distance from the house for the
bracket above).  The HD bracket is at approximately 21 feet off the ground,
lag screwed to 4 wall studs just under the eve.  Then the tower is guyed
close to the top (wondering about the strength of the Phillystran I chose,
2100 lb).  The way the tower is oriented, one leg points toward the house
and the other two are away from the house and parallel to the side (this way
only one guy terminates in the roof rather than two).  The parallel legs go
to guys anchored with 3000 lb screw anchors, but since there is a grade on
that side of the house, they terminate at approximately 6 feet lower than
the tower base (the angle of these guys is a little less than it should be
because of the grade drop, they are approximately 45 feet from the tower
base, close to the property line, it should be more to make up for the
effect of the grade).  The leg and guy toward the house anchor to the roof
(two sistered roof joists with an eye bolt on the guy angle
through) and
that guy is shorter because of where it terminates, the roof.  The angle of
that guy is proper to the others, actually further away because of the
sistered joist location (larger angle between tower leg and guy).  Perhaps I
should make up a drawing showing the elevation view and send it to you?  I
already have a site plan with the tower location shown.

Other pertinent information is that the tower has a tapered top section and
a galvanized pipe (short) mast, think it was 1" I.D., the largest that would
fit the top section without removing the bushings.  The antenna would mount
just above the top of the tower top section, minimal mast length protruding
or present between antenna mount and tower top.  The Phillystran goes all
the way to the screw anchors, no steel guy close to the ground.

Would you be able to provide the PE services I need (assuming I determine
EXACTLY what the township requires)?  If so, approximately how much would it
cost?

Thank you very much and 73,

Bob, WA2T
----- Original Message -----
From: "Hank Lonberg" <kr7x at comcast.net>
To: "'Bob A. Booey'" <rentwist at comcast.net>; <towertalk at contesting.com>
Sent: Saturday, November 19, 2005 12:33 AM
Subject: RE: [TowerTalk] Help with PE certification of tower in NJ

> Bob:
>
> First off I am a licensed P.E. in New Jersey among other
> states.
>
> The IBC 2000 or even 2003 does not mention that a tower
that
> is 30' or less above a roof is ok. It does not mention
> towers in any prescriptive design configuration. It does
> propose procedures to determine environmental loadings on
> tower structures and even references the TIA/EIA 222-F as
a
> recognized national standard for antenna bearing tower
> design.
>
> I am not sure if I understand your installation.
> Does it have a concrete base?
> Is it both guyed and bracketed to your house?
>
> What does the township require for you to get a permit?
> Sealed engineering calculations and plans or just sealed
> calculations?
>
> There is a later revision of the IBC. The most recent
> published is the IBC 2003 and I believe that NJ has
adopted
> that as the latest building code.
>
> Your tower installation is more than enough for the 5.5
> square feet of antenna load.
>
> Regards
> Lonberg Design Group, Ltd.
>
> Hank Lonberg, P.E.,S.E. / KR7X
>
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Bob
> A. Booey
> Sent: Friday, November 18, 2005 3:58 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Help with PE certification of tower
in
> NJ
>
> Hello Tower Gurus,
>
> I have installed a 55 foot Rohn 25 antenna tower on my
> property, secured to the side of the house under the eve
> with a HBUTVRO (HD house bracket) at 21 feet and guyed
with
> Phillystran HPTG2100I (2100 lb.) at 50 or so feet.  Two
guys
> are secured with 3000 lb. screw anchors out 45 feet (like
> the Rohn GAS604 but rated a little higher) and the third
> goes into an eye anchor (like the GAW 25) in the house
roof
> through two sistered roof joists.
>
> The problem is that the township (Brick) got after me for
> permits after I had put the tower up (but before I put the
> antenna up).  After a (long) time of them trying to figure
> out what was needed, they asked me to file for permits,
> which I did.  They said that if the base wasn't a footing
> (i.e. another bracket with cantilever), that I would not
> have had to get permits.  the tower top is less than 20
feet
> above the peak of the house roof.  Anyway, I supplied all
> the pertinent Rohn design information on the guying
details
> (110 MPH zone, about 10 min from ocean), concrete base,
> antenna wind load (ATB-34, 5.5 sq. ft.), etc...
>
> After a bunch more time they came back and said I need to
> have the design and installation certified by a licensed
PE.
> I consulted a friend who once had a tower in Wall, NJ.  He
> concurred on the PE thing but thought that there was
> something in the International Building Code allowing
towers
> attached to a house to be up to 30 feet above the peak of
> the roof (without PE certification?)
>
> So, I am writing this to ask:
>
> - The advice of anyone in NJ who has erected a tower and
> what is required (If a PE cert., a recommendation would be
> great)
>
> - Any critique of the design as I have described it.
>
> - Any advice about the year 2000 IBC (what Brick cited) as
> it pertains to a tower attached to the house but with a
> concrete base.
>
> Thanks in advance and 73,
>
> Bob, WA2T
>
> _______________________________________________
>
> 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
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> 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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