Aluminum Fence Systems
Aluminum Fence Systems
The blog cover image is for reference purposes only and does not depict the actual Medallion Fence product.
If you live in Oak Bay, White Rock, Lunenburg or anywhere around Halifax Harbour, you already know the film. It shows up on the windshield two days after a car wash. It hazes the patio glass. Run a finger along a deck railing in February and it comes back gritty and slightly damp, even when it hasn't rained in days.
That film is sea salt, and your fence collects it every day of the year.
Most Canadian fence advice is written for Ontario, where salt arrives by snowplow and leaves with the spring thaw. On the coast it never leaves. It comes in on the wind, settles on every surface the rain can't reach, and pulls moisture out of the air to keep itself wet. That changes four things: which material makes sense, which hardware you can trust, how often the fence needs a rinse, and what the warranty will actually cover.
Breaking surf throws fine droplets of seawater into the air, and the smallest ones stay airborne for a long way. When they land, the water evaporates and leaves salt crystals behind.
This is the part that matters for metal. Sea salt is hygroscopic. Sodium chloride starts drawing water vapour out of the air at around 75 percent relative humidity, which on the BC coast and in the Maritimes describes a large share of the year. Once that happens, the surface carries a thin film of brine even on a dry afternoon. Brine is an electrolyte, and corrosion needs an electrolyte. A fence in Kamloops dries out between rain events. A fence 300 metres from the Strait of Juan de Fuca often never fully does.
Salt deposition drops off quickly as you move inland. Field research on marine atmospheres has found salinity falls roughly exponentially with distance from the shore, so the first few hundred metres take the heaviest load. Distance alone is a blunt measure, though. A lot on an exposed headland with onshore wind can be harsher at two kilometres than a cove lot at 200 metres sitting behind three rows of houses and a stand of spruce.
Specifiers have a better tool than distance: ISO 9223, the international standard for atmospheric corrosivity. Category C3 covers typical urban sites and low-salinity coast. C4 covers coastal areas with moderate salinity. C5 covers coastal sites with high salinity. The difference shows up clearly in zinc loss. In the first year of exposure, zinc loses roughly 0.7 to 2.1 microns in C3 and 4.2 to 8.4 microns in C5.
A simple field test for homeowners: if you can hear surf from the yard, see salt haze on your windows within a week of cleaning them, or watch outdoor light fixtures pit and blister, treat the site as C4 at minimum and probably C5.
This one surprises people. The face of the fence that takes the full force of onshore weather often looks better than the face toward the house.
Rain rinses. Salt that lands where rain can't reach just keeps building up: the underside of rails, the inside of a gate frame, picket bases behind a hedge, the run under a roof overhang or beside the garage wall. Powder coating manufacturers say this directly in their maintenance literature, flagging sheltered areas as higher risk than exposed ones.
Vancouver's wet winters help the exposed faces. They do nothing for the bottom rail tucked behind the hydrangeas.
A steel fence depends on the zinc or zinc-alloy layer under its powder coat. While the powder is intact, that zinc sits untouched. Once the powder is breached by a string trimmer, a ladder, a gate latch or a field cut, the zinc starts sacrificing itself to protect the steel. On the coast, that sacrifice happens faster.
Run the numbers. G60 galvanized sheet carries roughly 12 to 13 microns of zinc per side. At the C5 rate of 4.2 to 8.4 microns a year, the zinc at an exposed scratch could be used up in somewhere between a year and a half and three years. Treat that as an estimate rather than a forecast, because zinc loss slows as corrosion products build up, and zinc-aluminum-magnesium coatings protect damaged edges better than plain galvanizing. The direction is still clear. By the ocean, a steel fence is only as good as the owner's touch-up habits.
That doesn't rule steel out. A site set well back from open water, screened by other buildings, with a Zn-Al-Mg substrate and someone committed to sealing every chip, can be a reasonable steel job. On the front row facing open water, aluminum is the safer call.
No ASTM or CSA standard defines "marine grade." In boatbuilding the term usually points to the 5000 series alloys such as 5052, 5083 and 5086, which are used for hull plate. Fence pickets, rails and posts are extrusions, and extrusions come from the 6000 series: 6063, 6005 and 6061 are the common ones. Medallion's Alu-Tuff panels, for example, are extruded from 6061 in T4 and T6 tempers. 6061 has a long record in docks, gangways and boat fittings, which is why fence makers use the label. The honest spec is the alloy and temper, not the adjective.
Aluminum also isn't immune to salt. It doesn't rust because it contains no iron, and its oxide film is very stable. Chloride is one of the few things that can break that film locally, which produces small pits and a white powdery corrosion product. Under a powder coat, the bigger coastal risk is filiform corrosion: thin, worm-like tracks that creep under the film from a cut edge or a chip in humid, salty air.
The defence happens in the factory, not the backyard. It comes from proper cleaning and etching of the aluminum, a conversion coating before the powder goes on (Medallion uses chromate conversion under Alu-Tuff), and a high-performance powder. For the powder, ask which AAMA class it meets. AAMA 2604 requires five years of South Florida exposure testing; AAMA 2605 requires ten. Super durable polyester powders are generally formulated for the 2604 level, but ask for the data sheet rather than assuming.
What aluminum gives you is a far more forgiving failure mode. A scratched aluminum picket gets a blemish. A scratched steel picket starts a countdown.
Panels rarely go first. Hinges, latches, screws and anchors do. They are small, they trap brine in crevices, their moving parts wear through coatings, and they are usually a different metal from the frame.
Type 304 (often stamped A2 or 18-8) is fine inland. At the coast it tends to develop brown "tea staining" and pitting. Type 316 (A4) adds 2 to 3 percent molybdenum, which lifts its pitting resistance equivalent number (PREN) to roughly 23 to 28, compared with about 18 to 20 for 304. Specify 316 for every fastener, hinge pin, spring and anchor within sight of salt water. Even 316 can tea stain in sheltered spots, so it needs rinsing too.
In a salt film, aluminum is the anodic partner to stainless, so any galvanic attack happens to the aluminum around the fastener. A small stainless screw in a large aluminum rail is generally an acceptable ratio. The reverse is not. Where you can, break the contact with nylon or EPDM washers. During repairs, never mix in brass, copper or bargain zinc-plated screws from the hardware store.
Modern premium platings test well in salt spray and are rated compatible with aluminum. On an exposed C5 lot, 316 stainless is still the conservative choice.
Self-closing hinges and self-latching hardware, required on pool enclosures across most provinces, contain springs and small pins. Ask what they are made of before you order.
Fresh concrete is alkaline and aluminum doesn't like it. Keep the coating intact where the post enters the footing and crown the concrete so water sheds away from the post. Use 316 anchors for base plates on seawalls or deck slabs. Copper-based preservatives in modern pressure-treated lumber also attack aluminum, so where panels mount to PT posts or deck framing, use an isolation membrane and stainless screws.
A fresh-water rinse removes chloride before it builds into a permanent brine film. It costs a few minutes and the water from a garden hose.
How: work top down with a garden hose. If you use a pressure washer, stay well back and keep it under about 500 psi. At least one aluminum fence warranty is voided by higher pressure. When the fence needs more than water, use a mild pH-neutral soap and a soft cloth, then rinse off all soap. Never use solvents or abrasive pads.
Where: concentrate on the sheltered zones: rail undersides, gate frames, hinges, latches, post bases and anything behind landscaping.
How often: powder coating suppliers link cleaning frequency to exposure. One major supplier's guide calls for cleaning every three months at surf-exposed sites and every six months on calmer shoreline. One large fence manufacturer recommends quarterly cleaning for all its powder-coated fencing and monthly in harsher conditions. A Canadian coastal schedule that works:
Early spring, once nights stay above freezing, to clear winter sea salt plus road salt and ice melter.
Early summer.
Early fall.
Late fall, before freeze-up.
After any major storm, whether it's an atmospheric river in BC or a post-tropical system in Atlantic Canada.
Front-row C5 lots should add monthly rinses through the stormy months where possible. Don't rinse when it will freeze overnight, since water left in hinge mechanisms will expand.
Keep a record. A dated phone photo of each rinse takes five seconds. Some coastal warranties require proof of maintenance, and a camera roll is proof.
Touch up promptly. Seal any chip that exposes bare metal, and make sure every field cut is deburred and sealed. One major fence maker requires three coats of touch-up on cut ends in saltwater environments instead of the usual two.
Distance clauses are standard in this industry, and many buyers only discover them after something fails. A few published examples:
Fortress Building Products' fencing warranty, which applies in Canada as well as the US, cuts the warranty term to 25 percent within one mile (1.6 km) of a saltwater coastline and to 50 percent between one and ten miles (16 km). A 20-year steel warranty becomes 5 years or 10 years. Owners must also perform maintenance and be able to show a record of it.
A powder-coat warranty from US aluminum fence maker Ideal, as published by one of its dealers, drops from five years to one year within a mile of the saltwater coastline.
TrueBound's aluminum fence warranty states that it does not apply in marine, salty or coastal environments at all.
Sixteen kilometres covers most of Greater Victoria, all of the Halifax peninsula and nearly all of Prince Edward Island. If you live on the coast, assume a distance clause applies until a supplier shows you otherwise in writing.
Is there a distance clause, and how is distance measured?
Do estuaries, tidal rivers and salt-chlorinated pools count?
What maintenance do I have to prove, and how?
Is hardware covered separately, and for how long?
Is the warranty pro-rated, and does it transfer when the house sells?
Possibly. The lower reaches of tidal rivers and estuaries can be brackish, and warranty wording like "saltwater coastline" rarely says whether they count. Get the answer in writing.
Yes. Salt pools usually run around 3,000 ppm against roughly 35,000 ppm for seawater, so the water is far less salty. The problem is that splash dries on the same few panels every day and the salt concentrates there. Some warranties have a separate clause for fencing near salt pools. In season, rinse the pool-side face weekly.
Wind performance comes from post size, post spacing and footing depth more than from the alloy. Anyone who cleaned up after Fiona in 2022 knows what an exposed site can see. On exposed lots, choose a heavier commercial post section, tighten the spacing, and get footings below frost depth.
Nobody rinses from October to May, and that is storm season. Build a fall and spring rinse into your opening and closing routine, or put it on the property manager's list.
Once a year at high pressure is the wrong way round. Frequent, gentle rinsing does more good than one aggressive wash.
On the coast, the material you choose matters less than the details nobody draws: the hardware, the cut ends, and who rinses the fence after a storm. Put aluminum on the front row. Specify 316. Write the rinse schedule into the handover. Get the warranty's distance clause in writing before anyone digs a post hole.
Request a quote from Medallion Fence or call 905-832-2922, and ask for the alloy, finish and warranty documentation along with your pricing.
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