Managing Old Rooftop Antenna and Satellite Dishes
In recent blogs, here on our website, we looked at a couple different issues related to satellite dishes. Some of the particular issues that we discussed were related to the mounting of the satellite dishes. When the satellite dishes are installed on sleds, it’s simply better to separate the sled from the rooftop membrane with a sacrificial slip sheet. Today we’re looking at similarities issues, but we’re looking at a series of different satellite dishes that have been mounted through the rooftop membrane. This type of mounting is problematic.
We’re also looking at many defunct and abandoned type rooftop communications devices. Some of them are simple historic antennas. These old aluminum TV antennas are rarely seen in residential type roofs or in many buildings where they’re exposed from the street, in modern times, up until about the 1980’s or 1990’s. Somewhere around that time technology changed. We basically stopped using analog type television antennas and switched to the modern satellite dish type alternatives and or signals that went directly through the cable.
The picture below, for example, shows a low slope modified bitumen roof with several antennas mounted directly through the roof membrane bolting and mounting through the horizontal or low slope membrane is generally problematic.
The next picture below shows a historic type of antenna that is mounted to the side of the building next to the low slope roof. This is a better installation because it avoids a penetration or a fastening mount through the modified bitumen roof membrane. All mounting or fastening through the horizontal or low slope area of the roof should be avoided because it leads to leakage, in almost all cases.
Even when sealed on top of the fastener, if a sealant is not applied at the area underneath the base plate of the antenna or dish, etc., it can still lead to leakage. As well, most gun applied sealants are not as long lasting as intended low slope membrane life cycles. Even though gun applied sealants are used at areas of roofing installations, this is generally not, solely, a sufficient barrier.
In the majority of cases where we find this type of historic antenna, they have already been abandoned and are no longer in use. These types of antennas were used way before the modern wave of technology for televisions and or communications.
Like the antennas shown in the picture above, the next picture shows an antenna mounted with bands or straps that wrap around a brick chimney. This type of location for mounting is not as problematic to the roof membrane because it avoids penetration or piercing through the membrane itself. Nonetheless, as this antenna is defunct and or abandoned, it serves no useful purpose here on this rooftop.
We have had to make repairs to roofs where old antennas have collapsed and fallen and pierced through the membrane of a single-ply roof. Even though the risk of leakage through mounting fasteners is decreased, there are other risks associated with antennas. At points throughout the life cycle of a brick chimney, the chimney will need to be repointed. When the chimney is repointed it will need to be accessed at the surface of the brickwork. The bands used to mount these antennas block access to the surface required for repointing.
Often, people think of chimneys as being very separate from roof systems. We agree, to an extent. Generally, chimneys and brick facades, for that matter, have little to do with the roof itself. Here though, and particularly with many different types of configurations of flat roofs, the roof mustvterminatevandvsral to the chimney. Even though they’re separate systems, from a functional perspective, they matter.
As you can see in the picture above, the chimney is a penetration through the roof itself. Essentially the roof doesn’t require there to be a chimney, for the sake of the roof. However, the chimney happens to pass through the roof because the chimney must be built in a way that allows exhaust gas and indoor ventilation to move freely above many elements of the roof itself.
In this coming week we’ll talk about some of the elements of preservation of rooftop chimneys and we’ll also look at alternative types of installation. As we mentioned above, it’s always better to not bolt through the horizontal or low slip area of the rooftop membrane installation. For a lot of reasons, bolting through the membrane can be problematic. Without special types of sealant or additional roofing installations applied, the bolts can lead to or cause water leakage around the areas of their instalation.
We provide this information here on our blog, and our website, to help our customers and future clients, and we recommend every building owner in DC who values the longevity of their roof (and their investments) and building use a contractor who values the simple and important principles of proper roof construction like Dupont Roofing DC. Our company specializes in flat roofing here in Washington DC and we’re happy to help building owners of almost all types.
Learn more about our company and the proper techniques of working with roofing on historic buildings in Washington DC here on our blog at DupontRoofingDC.com, and you can call us at (202) 840-8698 and email us at dupontroofingdc@gmail.com. We are happy to help and at least talk through options.
