free the net

The basic idea of a non-penetrating roof mount is to install various antennas onto an existing roof structure without altering the roof or causing damage to the building structure. Using almighty Google, it is easy enough to find various vendors of non-penetrating roof mounts, BUT with a little imagination and outside the box thinking its possible to build your own custom multiple satellite TV dish/antenna non-penetrating roof mount. Since a picture is worth a thousand words, here is a series of pictures for people thinking about buying, building a custom non-penetrating roof mount or installing various kinds of outdoor antennas.

The 
cable on the solar panel was shorter than the length of the flagpole so I  adjusted everything to fit just right

The non-penetrating roof mount pictured above was built out of made out of 1 5/8" fence railings (that can be bought at any Home Depot, Lowes or similar home improvement center) and is held together by Hollaender industrial connectors. An anodized aluminum, telescoping flagpole was used to mount a state-of-the-art solar-powered WiFi repeater as high as possible, so that the signal would cover a larger area. FYI total time to assemble the parts into a multiple satellite dish/antenna non penetrating roof mount was less than 2 hours.

use of clear vinyl tubing over u-bolts to keep everything in place

Note the use of clear vinyl tubing over the u-bolt to increase the coefficient of friction. Basically this was done so the waterproof box containing the radio and battery are less prone to sliding down the flag pole; furthermore since the walls of the flag pole are pretty thin, the nuts do not have to be overly tightened (which would deform the anodized aluminum telescoping pole).

a homebrew non-penetrating roof mount for a satellite TV dish and a solar WiFi system

The anodized aluminum flagpole is kept in place by slipping it over the over the 1 5/8" fence railing. What you can't see in the pictures is a bit of duct tape wrapped around the fence railing to give the setup a bit more of a friction fit.

a homebrew non-penetrating roof mount is built out of materials that will outlast the electronics

The solar panel is secured in place with UV rated zip ties, note that the Hollaender industrial connectors allow the non-penetrating roof mount to be leveled, cinder blocks are used for ballast.
The non-penetrating roof mount shown here is actually being used to deliver satellite and Wifi signals to a multiple dwelling unit investment property that I had totally remodeled. Over the years I discovered or perhaps re-discovered a few best practice tips that might be of some use.

Notes about dissimilar metals

To minimize electrolytic corrosion when two different metals are in moist contact, their electrolytic potential should be as close as possible. The reason I am including a note about dissimilar metals is because the whole non-penetrating roof mount was grounded by attaching a copper grounding clamp to the galvanized fence railing. To prevent any electrolysis effect I'd suggest using dielectric grease on the connection between two the different types of metal.

In general copper should never touch galvanized material directly without proper joint protection because water shedding from the copper contains ions that will wash away the galvanized (zinc) covering. Stainless steel can be used as a buffer material, but you should be aware that stainless steel is not a very good conductor. If it is used as a buffer between copper and galvanized metals, the surface area of the contact should be large and the stainless steel should be thin. Joint compound should also be used to cover the connection so water can not bridge between the dissimilar metals.

Notes about grounding

In the early years SoCalFreeNet experienced a number of WiFi radio failures on various roof tops which we suspect was caused by wind or rain induced static buildup. To eliminate static buildup from destroying radios, the group started using dedicated grounding in various installs.

Since this non-penetrating mount is being used for a satellite dish as well as an omni WiFi antenna, a grounding block with a minimum 10 AWG ground wire in accordance with section 810.21 of the national electrical code should be the very minimum protection used with any satellite dish or outdoor Wifi gear installation. For the Meraki with a Reverse-Polarity SMA Jack connector, plans are to install a grounding device from hyperlinktech.com.

Notes about solar panels

Solar panels should always face true south in the Northern Hemisphere. The winter season has the least sun, so you want to make the most of it. The tilt should be designed so that the panel points directly at the sun at noon. To calculate, multiply your latitude by 0.9, and add 30 degrees.

For example: San Diego is about 32 degrees North of the equator so:

32 X .9 + 30 = 50 degrees tilt from horizontal

The photos above do reflect the optimum angle for the solar panel, it was just a quick and dirty "secure" example of what is possible without a special bracket for the solar panel. BTW one benefit of not using a special bracket for the solar panel and attaching it high up on the telescoping flagpole is it eliminates the problem of wind-loading.

Notes about roof sheathing rot

Traditional non-penetrating roof mounts that use some form of concrete for ballast, IMHO can lead to premature asphalt roofing surface failure. Basically I'm thinking about roof sheathing rot which is caused by persistent condensation by the mount/ballast that traps moisture and does not allow airflow.

water pooling on a roof under a non penetrating roof mount

This photo from a thread on DSL Reports is an example of a non-penetrating roof mount where water pools under a rubber mat (that is suppose to protect the roof and keep the mount from moving). In a case such as this my big question is what happens to the roof and the structural integrity of the building when moisture causes problems somewhere down the line...

By minimizing area of physical contact of the non-penetrating roof stand from the asphalt roofing surface and maximizing the airflow, its possible to eliminate the potential problem of roof sheathing rot; also note by making the mount wider than a standard off the shelf non-penetrating roof mount, this makes the rig I put together very stable and with long moment arms requires just four blocks of ballast.

If you have a non penetrating roof mount that sits on asphalt roofing I'd suggest attics should be inspected annually for water stains on the underside of the roof sheathing. Personally I've always wondered why any building owner would allow satellite TV installers to use non penetrating roof mounts that allow the buildup of condensation because of the very real and unappreciated issue of roof rot which can lead to really expensive problems to fix like attic mold.

Notes about a satellite dish policy

Since I own a few rental properties myself thought I'd add one last bit of info about a satellite dish installation policy. Basically the FCC permits an owner of rental property to restrict installation of satellite dish/antennas that would damage a structure by drilling any holes through interior or exterior walls or through the roof. However renters may install antennas within their leasehold, which means inside the dwelling or on outdoor areas that are part of the tenant's leased space and which are under the exclusive use or control of the tenant. In other words a tenant in an apartment is allowed to put a dish on a non-penetrating mount in balconies or a patio area which is part of their unit BUT not in common areas such as decks, hallways or yards.

Bottom line as an owner/manager for a satellite dish installation or any other antenna such as an omni for an 802.11 network, I'd look into having a written policy for a satellite dish or other antenna. I'd also require drawings, specifications and calculations be provided by any installer or service provider so as to eliminate problems with damage to the structure, damage to electrical systems, etc. which IMHO are common sense ways to avoid an ugly dish install.


Photos courtesy of UGLYDISH.com

Comments, suggestions or questions

If ya want to eMail me any comments, suggestions or questions about non-penetrating roof mounts try:

super_genius_hates_spam (at) phaster (dot) com

but just like the stock market there are no guarantees of a return.