Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Mounting a beam on the roof of a Cape. Possible?  (Read 510 times)
WB2HTO
Member

Posts: 53


WWW

Ignore
« on: September 28, 2009, 09:46:18 AM »

With limited funds and limited real estate (in other words, a tower is not under consideration) wondering if anyone else has mounted a beam on a Cape-style house that has no attic or crawl space (you can see an aerial of the house on www.bambinomusical.com/WB2HTO)

I've looked at mounts such as this one:
http://www.glenmartin.com/catalog/page155.html and am wondering if anyone has managed to pull this off.

Thanks

David
Logged
AA4PB
Member

Posts: 13032




Ignore
« Reply #1 on: September 28, 2009, 10:05:05 AM »

You're going to have to add some bracing. Since you cannot get inside the only option would be to add it on top of the roof. Perhaps some pressure treated 2x6 under the legs of the tower and lag bolted thru to the rafters on the inside. Paint the 2x6 to match the roof color and use silicon caulk to keep water from getting underneath.

Depending on how much trouble you want to go to and how the inside ceiling is finished I suppose it would also be possible to cut some drywall, put bracing on the inside, and then redo the drywall and paint.

The one thing I would NOT do is to just lag bolt the tower to the plywood roofing. You might loose some roofing in the next big wind storm.
Logged
WB2WIK
Member

Posts: 20666




Ignore
« Reply #2 on: September 28, 2009, 11:52:33 AM »

I've used Glen Martin roof towers for many years (I also have ground-mounted towers, but you can never have too many antennas...) and they're very good.

Inexpensive, lightweight, strong, easy to assemble and because they have four legs, once installed you can tilt them over in either of two directions, which can be a very handy feature.

If you cannot access the attic, you need to find out where the rafters are.  A stud finder (electronic instrument) might work for this.  Sometimes roofing is too thick, and all wood also, so stud finders are fooled and can't really find the rafters through the roofing.  In that case, you drill pilot holes!  Yes, I've done this, on pretty much every house I've ever owned (15 of them now) and it's non-destructive.  

I use a long but small diameter drill bit, like 1/16" x 5" or so, and start drilling.  You can tell if the bit goes right through the roofing, or if it hits a rafter.  Then, by drilling 1" to the left and right of the "I hit it!" hole, you can determine the approximate center of the rafter.  Mark that by putting a wire coat hanger bent to prevent it from slipping all the way through (or a screw, or some other convenient "marker") and move 16" to the left and right of that location to see if you find two more rafters, on 16" centers.

Sometimes, they're not.  I've found rafters on 24" centers, or on "not really quite" 16" centers, and all sorts of stuff.  But with patience you can find three in a row across the roof, on each side of the peak.  Mark all "rafter centers" and then use permanent roofing patch to patch the other pilot holes.  You can get colored patch material that dries in 12 hours and fully cures in 24 hours, is completely weatherproof, and matches the color of your roofing so it cannot be seen at all, even with a close inspection.

Once you have the rafter centers marked, use a pressure treated (and then painted to a color you like, probably to match the roofing color) 2 x 6" overlapping three of them in a row on each side of the roof peak, and appropriate lag screws (I use hex head lag screws, usually 7/16" or 1/2" x 7-8" long, with fender washers under the heads to form a permanent weatherproof seal against the wood) to mount these exterior supports.

Then, you lag the roof tower mounting brackets to those using similar materials, and use roofing patch on all bolt heads.  I use that very sparingly so I can remove the bolts if I want to.  It does not take "much" roofing cement (I use "Henry" brand, which is fibreglas filled and incredibly strong) to do a wonderful job.  Probably 8 ounces is enough to patch everything.

When you find the locations for the mounting brackets, of course the tower must be attached to them!  Use a carpenter's level to assure the tower is perfectly vertical, measured from multiple directions; mark the hole locations for the brackets, remove the tower with its brackets, and drill.

My 9' G-M roof tower at my current home was installed by me, from "start to finish," including "finding the rafters," in less than one hour.  It really doesn't take long.

I've tilted it over a few times for service or antenna changes over the past 9 years, and it still looks new, shiny, and exactly as it looked when first installed.  In torrential downpours, it never leaked a drop -- nor did any of the other installations.

These things are a good deal for someone who already has a 2-story home -- you get a "free 20 feet" or more of elevation right from the start!

One disclaimer about the roof towers: They don't provide any "extra" hardware, at all.  As such, don't lose any...

WB2WIK/6
Logged
WB2WIK
Member

Posts: 20666




Ignore
« Reply #3 on: September 28, 2009, 06:25:58 PM »

If you'd like to see my G-M Engineering roof tower photographically, look here:

http://www.eham.net/articles/4148

That one's been up since November 1, 2000 and still looks brand new.  Never leaked a drop, and we do get some incredible rainstorms in winter.

It's installed on the peak of my roof, using exactly the method described in the previous post.

WB2WIK/6
Logged
WB2HTO
Member

Posts: 53


WWW

Ignore
« Reply #4 on: September 29, 2009, 05:21:35 AM »

Thanks for the suggestions, direction, caveats, and personal stories.  Now if someone can tell me how to convince my wife that this won't make the house look like "it just landed from Mars" then I'll be all set!
Logged
WB2WIK
Member

Posts: 20666




Ignore
« Reply #5 on: September 29, 2009, 11:47:58 AM »

Why ask her?

My excuse is always, "Hey the house is half mine, and I put this up on my half.  You can do whatever you want on your half."

Been working for me for 35 years.
Logged
K4DPK
Member

Posts: 1077


WWW

Ignore
« Reply #6 on: October 02, 2009, 07:44:42 PM »

Forgiveness is often easier to get than permission.

Phil C. Sr.
k4dpk
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!