Towertalk
[Top] [All Lists]

Re: [TowerTalk] unguyed with house bracket

To: "David Calder" <n4zkf@n4zkf.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] unguyed with house bracket
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Fri, 16 Nov 2007 05:52:24 -0500
List-post: <mailto:towertalk@contesting.com>


>
>
> I sure wouldn't try it. I don't even trust the fascia board as has been 
> said
> here. I also
> don't trust the side of the house. Both mine are bolted thru the roof.
>
> If your going to try it on a mobile home, make sure it's done where the 
> roof
> meets the wall
> at the top corner. That's probably the stoutest spot.

Having been there and done that, I'd not anchor more than a mast and 
multi-band vertical like the AV-640 or equivelant just above the roof. 
Certainly no tower or tribander. There is only a fraction of the strength 
present in a "stick built" home.

BTW, the facia on my shop is constructed of 2 X 6's and is structurally part 
of the roof which is substantial. I'd not hesitate to use it for bracketing 
a 40 or 50 foot tower as it is capable of passing the 800# requirement by 
ROHN, but I sure wouldn't do the same with my house. <:-)) I doubt it'd take 
more than a 30 or 40# pull on that facia.

Roger (K8RI)

>
> IMHO
>
> Dave
> n4zkf
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of AD5VJ Bob
> Sent: Thursday, November 15, 2007 8:50 PM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] unguyed with house bracket
>
> No one has answered my question about the Mobile home
>
> Can you bracket to the V at the side of a mobile home or will the mobile
> home hold it?
>
> It is a rental and I have permission for antennas, but wouldn't want to 
> pay
> for a new wall or anything :)
>
> tnx Bob AD5VJ
>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Jarvis
>> Sent: Thursday, November 15, 2007 1:58 PM
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] unguyed with house bracket
>>
>>
>> Lest the critical info be lost, there was a post which referred the
>> Uninitiated to a QST article on how to house-bracket correctly.
>>
>> Fascia boards are trim, not structure.  You must tie into the
>> structure.
>>
>> Using a 2x6 backing plate inside an attic sidewall  is preferred.
>> But here's an alternative which has worked:
>>
>> I did not have an attic, it was a flat-roofed house.  All I could do
>> Is lag screw into the roof joists  and the floor joists between the
>> first and second floors.  That gave me two points of attachment.
>>
>> My 'bracket' was constructed of 2x8's, 5' long, which spanned
>> 3 bays of Roof joists.  I used 1/2" x 12" lag screws into the
>> 2x12 roof joists, Carefully locating their centers, and pre-drilling
>> pilot holes, so nothing split.  There were 2 bolts at each of the 3
>> joists I intersected.  Each bolt was rated for 2700 lbs extraction
>> force, and considerably more in shear.
>>
>> The tower was captured by a sandwich of 2x6"s which were bolted to the
>> 2x8 backing beams in question.  So, I had the ability to withstand
>> something
>> >12,000 lbs pullout, and 24,000 lbs shear failure at each of the two
>> brackets.
>>
>> In turn, I calculated the windload with ice, from the antennas and
>> tower, and determined that at 90mph, it should be no more than around
>> 5,000 lbs at the point of the upper bracket.  With a more than 2x
>> safety margin, I felt reasonably comfortable.
>>
>> Let me point out that there were critical measurements involved, and
>> that a borescope was used to look at each pilot hole...and that each
>> lag screw was installed, removed, the hole inspected for structure,
>> and reinstalled.
>> You can't be casual about whether you've hit the beam or not, in that
>> situation.
>>
>> And NO, you can't rely on a double-wide at 10' to hold up a tower at
>> 40', with any kind of wind.  You don't have the overbuilt structure
>> that is common with site-built houses.
>>
>> n2ea
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk 

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>