ROHN BRM640M Non-Penetrating Roof Antenna Mount 4.00 in. x 4 ft. Mast
ROHN
Made in the USA!
Mast Dimensions - 3.5” STD. Pipe (4 O.D.) x 45-3/4”
This roof mount is able to support various Antenna EPA's depending on wind and Ballast load (see details). The base of the roof mount is 10' square with a 16” tray to fit concrete blocks, typically used as ballast. The base mount and mast pipe are Hot dip galvanized for corrosion protection and go together quickly.
This Item Ships LTL Freight ONLY.
Height and Antenna Loading capability are dependent upon ballast weight to counter the tip-over moment of the Windspeed rating desired. In addition to the Windspeed Loading Data found under the "Specification" tab (if Available), You need to Consult an Engineer to determine the Building Code Requirements and Load Bearing Capacity of the roof structure where you will be installing this mount. It is Important to choose a Mount and Mounting Location with a Picture of the Finished Installation in Mind. Be Sure to First select a location that lends itself to applying a Load without Compromising the Integrity of the Material you place the mount on top of; i.e. roof membrane, covering, decorative cover, etc., or the Structural Members beneath. Next consider the Location over a Lifetime of Adjustments, does it lend itself to modifications in Height or Direction? Larger Antennas increase the surface area presented to air movement and thus, Wind-load does increase. As the height of the mast increases from Its last attached point on the structure, the torque applied in cantilever towards the tip-over moment also increases with Antenna off-center Weight and Wind-Load EPA (Effective Projected Area), requiring a more substantive Downward Force and/or Load Dissipation; i.e. supplemental Down-guys may be required as to keep ballast weight within Load-bearing capacity. Keep the Distance Minimal from the Antenna to the Equipment you feed, as to minimize loss and the need for Amplification.
A Retention Tether SCK150 (Safety Cable Kit) is required for Commercial Installations to mitigate Loss and Damage to Property, Further, the FRM-PAD or FRM-MAT is recommended for all installations to prevent slippage, distribute weight more evenly and prevent damage to the roof surface
Download PDF
Antenna Mast Ground and Roof Base Mounts
Antenna Ground Base Mounts
Ground Level Base Mounts for Antenna Mast Poles typically provide for a Plate style Platform upon which will rest Antenna Mast and/or Telescopic Mast Poles of varying Outside Diameters, designed to take the weight and downward pressure of Down Guy Wires, Antenna Weight, Wind Load and the Mast itself and distribute/transfer to the foundation, pad, or soil. Being at ground level, it is important to elevate the surface upon which the plate will rest in comparison to surrounding grade as not to pool water and acids that would promote rust. The Plates typically come with a separate Stake which will fixate the plate to keep it from drifting. The stake can be driven into a foundation of gravel or concrete (better) and if integrally attached, can be direct embed into the soil itself for temporary fixtures.
The economy grade plates simply have the stake coming up through a center hole (about an inch) and the hollow mast tube rests on the plate covering this stake. As the stake and the Mast Tube will be of differing diameters, there is some rotational play as the Down Guy Wires provide the only means of securement and fixation. Premium Grade Base Plates will have a integral steel tube collar with set screws which will fixate and secure the mast in addition to the force of the Down Guy Wires. The base plates can be used in bracketed installations of One piece Mast Tubes or Telescopic Antenna Masts however; Manufacturers recommend that masts that rise 10 feet or more above the last bracket or guy level, should be guyed at this level also to keep from folding over in the wind.
Antenna Roof Base Mounts
Roof Base Mounts for Antenna Mast Poles are not centered upon a stake or fixated solely by the Down Guy Wires (keeping in mind there is no wall to bracket to) and therefore require a mechanical connection through the shingles, tiles, etc., past the vapor and weatherproof barriers to the structural load-bearing components that lay beneath. This attachment is usually made by means of lag screws and the watertight barrier is sealed with a pitch-pad between the base and shingle in which the lag screw will perforate and fixate.
Most Roof Mounts for Antenna Mast Poles these days are flexible enough to accommodate mounting on a Flat, Pitched or Peaked Roof location. Imagine a cup with two double jointed hinged feet with one on each side and you get the idea. This allows for the Antenna, Antenna Mast and Down Guy Wires to all be lowered and raised together even after the base mount being secured to the roof. The Universal style Cups may actually be a clam with two pieces squeezing the bottom of the mast pole via screws that draw to two pieces together. The cup style may come in a variety of diameters to accommodate a specific range of mast sizes then secured by set screws. It is important to note that as in the case of the Ground Base Mounts, No Base is "Freestanding" or "Self-Supporting" and rely on a combination of brackets and down guy wires to keep the mast pole in place and the antenna on target. The down guy wires then have to attach to another structural load-bearing component of the roof at several locations by means of round-eye lags, bolts and screws. The Pattern of down guys is 3 or 4 way. 3 way mostly used on the ground with 4 way mostly used on home roofs with a guy going to each corner.
