Satellite Dishes and Antennas on a Metal Roof
The technician wants to drill into your new roof. Here's why you should say no, what the alternatives are, and how to handle the mount you already have up there.
A technician arrives to install a dish, looks at the roof, and reaches for a drill. This happens often, and it is worth deciding in advance how you want it handled, because a lag bolt through a metal roof panel is a permanent decision made in about four seconds. The good news is that there are almost always better options, and most of them are easier than the roof mount.
Why drilling into a metal roof is a poor idea
A hole through a metal panel is a hole in the weatherproofing layer. It gets sealed, and the seal is a consumable material with a much shorter life than the roof around it. On a standing seam roof there is an additional problem: the panels are designed to move with temperature change, and a bolt driven through a panel into the deck pins that panel in place. Restrained thermal movement wallows out the hole, distorts the panel, and stresses the seam — and it does this quietly over years, so nobody connects the eventual leak to the dish that was installed six summers earlier.
Tell the installer before they arrive that the roof is metal and that no penetrations are permitted. Ask what mounting method they will use instead. It is a much easier conversation to have on the phone than on the driveway with a drill running.
The alternatives, roughly in order of preference
Most installations that could go on the roof can go somewhere better:
- ✓A wall or fascia mount on the side of the house, below the roofline — the most common substitute and usually the simplest.
- ✓A ground mount on a post set in concrete, which is ideal if you have clear line of sight and somewhere sensible to put it. It also makes future service easy.
- ✓A gable-end mount, which puts the dish on a vertical wall surface rather than a roof plane.
- ✓A non-penetrating ballasted mount — a weighted base that sits on a flat surface. Common on flat commercial roofs, occasionally useful on a low-slope residential section.
- ✓A chimney mount, using straps around the chimney rather than bolts into the roof. Only appropriate if the chimney is structurally sound.
- ✓A seam clamp on a standing seam roof — the same kind of hardware used for solar, providing an attachment point without a penetration. Verify clamp compatibility with your specific seam profile and confirm the load is appropriate.
- ✓A deck, railing or accessory mount, which is worth considering before anyone climbs anything.
Does line of sight actually require the roof?
Sometimes yes, often no. Satellite dishes need a clear view of the sky in a particular direction, and a technician will default to the roof because it is quick and usually clear. Before accepting that, ask whether a wall mount on the correct side of the house, a gable end, or a post in the yard would work. In many cases it will, and the technician simply has not been asked. If height genuinely is required, a mast on a gable end or a post can often get there without touching the roof plane.
Does a metal roof block the signal?
Not for a dish that has an unobstructed view of the sky — the roof is behind the dish, not between the dish and the satellite. Where metal can matter is with indoor equipment: a metal roof, like any large conductive surface, can affect indoor reception of over-the-air broadcast signals and can attenuate some wireless signals passing through the roof plane. In practice this shows up as an argument for an outdoor antenna rather than an attic one, and occasionally for thinking about where a cellular booster antenna goes. It has nothing to do with a properly aimed satellite dish.
Grounding and bonding
Antennas, masts and satellite dish installations have electrical bonding and grounding requirements, and these are not optional or cosmetic. They are handled by the installer under the electrical code that applies to the work, and a proper installation includes a bonded ground conductor to the building's grounding electrode system. If a technician mounts an antenna and leaves without addressing grounding, that is worth questioning. This is also a good reason to keep the installation off the roof plane, where routing a proper ground conductor is more awkward.
The dish that is already up there
Plenty of Ontario houses have a disused dish or an old antenna bracket on the roof, often from a service nobody in the household remembers subscribing to. These are worth dealing with, particularly if a new roof is going on:
- ✓Every abandoned mount is a set of penetrations with sealant that is years past its useful life.
- ✓The bracket catches sliding snow and debris, and can damage panels or trim when it moves.
- ✓Removing it leaves holes that must be properly patched — this is roofing work, not a job for a tube of caulk.
- ✓If a new roof is planned, have the old hardware removed before the work rather than roofed around.
- ✓Cabling left behind should come off with it, including anything running under trim or through a soffit.
If a penetration is genuinely unavoidable
Occasionally there really is no alternative. In that case the penetration should be planned and detailed properly rather than improvised: located deliberately relative to panel seams and framing, flashed with a purpose-made component, integrated so that water is shed over the top of the layer below rather than held out by sealant alone, and installed with hardware compatible with the roof metal to avoid galvanic corrosion. Have the roofing contractor do it, or at minimum specify it. Then note it in your records, because it becomes an item on your annual inspection list for the rest of the roof's life.
Frequently Asked Questions
The installer says they do this on metal roofs all the time. Should I let them?
Doing something frequently is not the same as doing it well, and the technician will not be there when it leaks. Ask what specific method they use, what flashing component they install, and how they account for thermal movement. If the answer is 'screws and sealant,' find another location for the dish.
Can I use magnetic mounts on a metal roof?
For a permanent antenna or dish, no. Magnets will not resist wind loading reliably, they can slide and scratch the finish, and they do not work at all on aluminum panels. They have their uses for something small and temporary, not for anything that has to stay aimed.
Will removing an old dish leave a visible patch?
There will usually be some evidence — a repair, or a replaced section of panel, and the surrounding roof has weathered while the covered area has not. A proper repair is watertight and reasonably discreet. It is still far better than leaving failing sealant in place.
Does mounting hardware affect my roof coverage?
It can, and it varies by manufacturer and installer. Before anyone attaches anything, check your project documentation and ask your roofing contractor whether the proposed method is acceptable for your specific system. Getting that answer in advance takes one phone call.
Get a Free Metal Roofing Quote.
We measure your roof remotely by satellite and deliver a written, itemized quote — same day, no obligation.