How to Install an Antenna Tripod

A roof tripod is only as strong as the wood its lags reach and only as dry as the seal under its feet. Most tripod failures are leaks and pulled lags, not broken steel. This guide covers how to install an antenna tripod from planning to plumb: finding the framing, fastening each foot, sealing the penetrations, setting the mast, then guying, grounding and working safely on the roof.

Before you climb: plan the tripod location

If you are still choosing between a tripod and a wall mount, settle that first with our comparison of a roof tripod vs antenna mast. Then plan its spot:

• Power lines first. Find the service drop and any overhead line, then check the spot against the clearance rule in our guide on how to guy an antenna mast. If the mast could fall onto a line, move the tripod.
• Height and line of sight. The antenna needs a clear view toward the transmitters; how high to mount a TV antenna covers how much height the site needs.
• Roof condition. Soft decking or worn shingles will not hold lags or seal well; fix the roof first.
• Attic access. You need it to find the framing and check for leaks later.

Roof safety and fall protection

Treat the roof as the most dangerous part of the job. NIOSH’s fact sheet Prevent Construction Falls from Roofs, Ladders, and Scaffolds states that falls are the leading cause of construction worker deaths on the job. It lists the factors behind roof falls, including no fall protection program or personal fall arrest system, incorrect anchorage, working alone at height and working in wind or rain.

Its recommendations for roof work:

• Implement a fall protection program, wear fall protection and use it correctly.
• Get training on fall protection, and have a trained person inspect the equipment before each use.
• Use correct anchorage for fall arrest systems.
• Extend the ladder side rails 3 feet above the roof edge.
• Use a buddy system when working at heights, and monitor the weather.

Employers must also meet the OSHA rules that apply to the work. If the roof is too steep or too high for the equipment and training you have, the job belongs to a crew that has both.

Roof tripod mounting: locating rafters or trusses

Every lag has to reach solid framing. A lag that only bites the roof deck will loosen in wind and leak. Find the framing from the attic, because shingles hide it from above.

1. In the attic, find the rafters or trusses under the planned spot and note whether the roof is framed with rafters or with engineered trusses.
2. Measure the position of each member from a fixed reference both sides can see, such as a gable wall, a plumbing vent or the ridge.
3. Transfer those measurements to the roof surface and mark the centre line of each member with chalk.
4. Spread the tripod legs to land on the marked lines, keeping the collar and the mast plumb.

Tripod legs rarely land on three members at once. Where a foot misses, fit solid blocking between two members from the attic so the lags have wood to bite. On engineered trusses, never cut or notch a truss member to make room, and fasten blocking without weakening the truss.

Tripod lag bolts and rafters: fastening each foot

Use the lags supplied with the tripod or the size and length its maker specifies. They must pass through the foot, any pad or flashing, the shingles and the deck, and still embed fully in the rafter, truss or blocking.

• Drill pilot holes at the size the instructions give, centred on the framing, so the lag does not split the wood.
• Drive the lags straight and snug, then stop. Overtightening crushes the shingles and can strip the hole.
• Use every hole in each foot that the instructions call for.
• If a lag misses the wood, pull it, seal the hole, add blocking and drive it again into solid framing.

Check from the attic that no lag tip came through beside a rafter instead of into it.

Sealant and flashing under the feet

Follow the tripod maker’s sealing instructions, and use roofing sealant suited to the roof material:

• Bed each foot, or its pitch pad, in sealant before the lags go in, so the sealant fills around every hole.
• Seal over every lag head and around the edges of each foot after tightening.
• Where you can, slip flashing under the shingle course above each foot so water runs over it, not under it.

Shingle roofs are the usual case for a tripod. Tile, slate, metal and membrane roofs each need their own flashing method; on a flat or membrane roof, a non-penetrating roof mount avoids holes altogether.

Mast height limits and guying

The tripod maker states how much mast the tripod can carry above its collar and when the mast must be guyed. It depends on the tripod, mast, antenna and any rotor, so take it from the instructions, not a rule of thumb.

Use mast sections sized to the tripod collar, seat the mast fully and tighten the collar bolts once it is plumb on two faces. If the instructions call for guys, fit them at the levels given; the guying method is in our guide on guying an antenna mast.

Comparing roof situations for a tripod

Not every roof suits a tripod:

Grounding and the coax run

A tripod mount does not change the grounding rules. Bond the mast and ground the coax as set out in how to ground a TV antenna before the system goes into service.

Run the coax down the mast with a drip loop, secure it so wind cannot whip it against the roof, and seal the entry into the house. If the job includes a mast-mounted preamp, see how to install an antenna preamplifier.

Where to find tripods and mounting hardware

The roof tripods category lists tripods in several sizes, and the antenna mast category lists the mast sections to go with them, within the antenna, tower and satellite division.

For pricing and availability, ask your sales representative through the Bursma contact page, or open a Bursma dealer account.

Frequently asked questions