Three walls, hold the floor

boathouse

As far as cottagey icons go, boathouses rank right up there with canoe Paddles, s’mores, and loons. Which is odd, really, because these waterfront garages, whether grand or utilitarian, are actually a rarity on the lake scene, with most cottagers making do with a regular dock or a sandy shoreline to park their boats. Sex appeal probably has a lot to do with all the attention: The fanciest boathouses are certainly lovely to look at in their multi-storeyed splendour, with architectural flourishes worthy of Sir Christopher Wren. They hog the spotlight because we’re all suckers for copper cupolas and ornate dormers.

But a boathouse doesn’t have to feature any of those fancy details, and can be as simple—or as complex—as you choose. In fact, the above-water design options for a boathouse are almost limitless, because once a solid foundation has been established, boathouse construction is pretty much the same as building a house on dry land, where interior finishes, windows, siding, and roof materials can be whatever your heart desires and your budget will tolerate.

Before you dream about what kind of boathouse you’d like to have, find out what kind you’re allowed to build. Bylaws vary widely from one municipality to the next (and even among different lakes in the same township). Some jurisdictions allow two-storey boathouses with living quarters above, some only accept single-storey boathouses, and many expressly forbid boathouses, period. Where new boathouses are allowed, their height and size—and how much shoreline they occupy—is tightly controlled. Visit your township office or talk to an experienced contractor well before the design process gets going.

Because most municipalities insist that boathouses and boatports must be designed or approved by a structural engineer before a building permit will be issued, you don’t need to become an expert on engineered trusses or laminated-veneer lumber to make sure your boathouse won’t collapse. But you should consider the number and size of the boat slips you need for your current—and future—flotilla. Rather than tailoring slips to specific boats, create one or two oversized slips that will give smaller boats lots of room to bob with wave action 
yet still be able to accommodate larger vessels in the future. It’s a balance between creating maximum mooring area and leaving enough interior dock space to comfortably access watercraft, store extra gear, and maybe set up that boathouse poker table you’ve always wanted.

A modern boathouse can easily support run-of-the-mill cottage runabouts lifted out of the water for winter storage, without any major modifications, but large or heavy boats may need special engineering. More critical, from a builder’s perspective, are the devices you might use to get those boats 
out of the water. Will boats be winched up and slung from overhead, or do you prefer to use a marine railway or a boat lift? If you plan to store small aluminum boats on the decking 
or on beams laid across the slips, how will they be lifted and swung? If the hoist system you want requires special supports or gets in the way of a garage-style overhead roller door, the building plans—or the doors—will need to change.

Other boathouse features can have spinoff effects. While running electricity, water, and sewer service into a boathouse isn’t a big deal, your cottage’s electrical service and septic system must be up to the job. Ignore these details at your peril, because a building inspector will not.

What lies below decks

While the topside of a boathouse might get our eye-popping adoration, the most crucial bits of the structure, the cribs or steel piles that support the undertaking, are rarely remarked upon, hidden from view like an iceberg’s bottom.

All that stuff under the water merits careful attention and precise planning, because the very location of a boathouse, 
at that angry intersection of water and land, makes it an easy target for every knuckleball nature can deliver. Existing in 
a constantly humid environment (there’s always water in the basement) and battered by wind and waves and wakes, a boathouse takes more punishment than a regular building. But its biggest challenge is frozen water. Ice damage comes in three flavours of destruction, says Garry Best, owner of Garry Best and Sons Carpentry in Lake of Bays, Ont. “The first is in the initial freeze-up, when you get black ice without any snow on top,” he explains. “Then the sun comes out and the top of the lake wants to get four feet bigger.” This expansion ice can shove wooden cribs around and bend steel structures. “The second time is in the spring, when lake levels are dropped three feet to accommodate spring runoff. You’ve got tons of ice locked around the structure of the boathouse, and when the water drops it wants to pull that structure down and away from shore.” You can avoid this situation by using an agitator or a bubbler system, but the big doomsday daddy, the scenario that can’t be controlled by feeble human efforts, is drift ice. “You get three million tons of ice moving at one mile an hour,” says Best, “and something’s gotta give.”

Cribs: Building on a box of rocks

One underwater foundation able to take this abuse is an array of wooden cribs filled with ballast rocks. Best suited for flat and shallow lake beds, cribs are simple, durable, relatively inexpensive, and easy to repair—which is handy, because they often need fixing. Sure, some crib-based boathouses have remained as solid as Gibraltar for 50 years, but many others have not—settling into the bottom, slowly slipping deeper into the lake, or getting pushed around by ice. Cribs don’t work in locations with really deep water, which, on many cottage lakes, is not far from shore. In addition, the multiple cribs necessary to support a boathouse disturb valuable aquatic habitat. Once you need multiple cribs, you almost certainly need an MNR work permit. Strike three against cribs.

Piles: A structural steel solution

New boathouses are often supported by beefy steel piles driven into the lake bed. These vertical “stilts” are then welded 
to horizontal steel beams above the water (and a whole whack 
of engineered cross-bracing) to form a strong foundation. Because piles disturb only a tiny fraction of the lake bed (unlike cribs), an MNR work permit is not required for their installation. This detail, along with the strength of the 
metal, makes steel piles the preferred foundation for most 
new boathouse construction.

While the concept seems simple, the devil, as always, is in the details. Scott MacDonald, of MacDonald Steel Docks in Huntsville, is a metal fabricator who specializes in structural steel for docks and boathouses. He explains that the Ontario Building Code requires the piles to be founded on solid bedrock or driven into the lake bottom “until refusal,” when the steel will not budge another inch. Where exposed bedrock is under shallow water, MacDonald will “drill and pin,” working on top of a barge or winter ice to bore a hole in the bedrock with a compressor-driven drill. He then welds a steel pin onto the end of a pile, lines up the pin with the hole, and drives the pile down until it bottoms out. That’s the easy method.

More difficult is when solid bedrock lies beneath overburden. When there are at least three feet of something like sand or gravel that can give lateral support, piles often don’t have to be pinned, just driven until they hit bedrock or refusal. As one length of pile is driven down, another is welded on, and the process continues. “We’ve pounded in 100 feet of pile before hitting bedrock,” MacDonald says. “You never know where it is.”
Even more difficult, some sites have 
a rubble-strewn bottom with boulders too small for pinning but big enough to deflect the pile off-target. Other lake beds are covered with loose silt, affectionately known as “loon shit,” which isn’t solid enough to provide lateral support. The steel must penetrate the glop, then get pinned into the underlying rock. “It’s hard,” says MacDonald. “You have to drill that hole, then get the 
drill out and place the pin in the hole—without the hole filling with silt.”

It helps if the builder knows the lake. “You might stay on a single pile and pound for 20 minutes and you’ll think you’ve hit refusal, but then the pile 
will break through,” MacDonald says, describing certain misleading layers 
of clay or stones. “I call them ‘crusts,’ 
and if someone wasn’t familiar with an area, they’d stop there and think it’s fine.” It’s not. Garry Best knows of a boathouse that, over many winters, “settled with snow-load until the front was two feet lower than the end on shore. The piles simply settled further down.”

How long will steel piles last? The short answer: It’s hard to tell. Much depends on the steel’s thickness, but lifespan estimates generally vary from 
30 to 50 years. Structural engineer Joseph Ball of Muskoka Parry Sound Engineering and Design points out that wave action and pH levels affect corrosion rates. “The bottom line is that steel-pile boathouses haven’t been around long enough for us to know.” Galvanized steel or epoxy coatings can extend the lifespan of a steel-pile structure, but both solutions are expensive, adding 20 to 30 per cent to the cost of the steel.

Structural steel is strong, but ice is stronger. That’s why many steel-pile-foundation boathouses (like crib ones) have bubbler or agitator systems to 
prevent ice from forming around them. 
If piles near shore are left exposed when water levels drop, they can be susceptible to frost heave and may need the protection of a heat cable running down into the ground with them.

Piles can usually take a “bump” from drift ice, but heavier collisions can be disastrous. “There’s a bit of a misconception that steel will resist the force 
of the ice. It will not. Not even close,” Ball states flatly. “If you are on an open portion of a lake, sticking out on a point, and the ice comes, you’re done. It’s just going to twist it up. Then you’ve got bent steel and it’s hard to fix.”

Floating boathouses

On shorelines with fluctuating water levels—think Georgian Bay or Lake of the Woods or the Thousand Islands—traditional crib or steel-pile boathouses can be impractical, either left high and dry (with boat entry by stepladder) or decks-awash (with seaweed in the beer fridge). Floating boathouses, supported by steel floats (or occasionally plastic 
or extruded polystyrene foam), offer 
the ideal solution, provided they can be reasonably protected from the wind-whipped fury that big-water locations dish out. “Floating boathouses have 
an advantage because they always have 
a perfect relationship with the water,” says Steve Taylor, a builder based in Thousand Island Park, New York. “But they can’t take a big sea.”

Because of their low impact on fish habitat, floaters are generally smiled upon by Fisheries and Oceans Canada and the MNR and don’t require a work permit. In some municipalities, floating two-storey boathouses with living space above are also permitted. These taller structures, however, do pose certain design challenges, according to Joseph Ball, who must not only calculate loads but also their distribution, to make sure the boathouse floats evenly. “My preference is for 
a symmetrical building design but, 
of course, nobody wants that,” he says. “If someone wants a big sitting deck 
on one side and a narrow finger on the other, it gets quite tricky.”

While many builders make floating boathouses that are connected to shore and solidly moored with massive concrete anchors, Claude Lord, a designer in Kenora, has a different approach, using custom-engineered floats made of timber and Styrofoam. “With millions of tons of moving ice here, no matter how much you weld and brace, it will take a dock right out.” So, for his projects on Lake of the Woods or across the Manitoba border in Whiteshell Provincial Park, Lord designs floaters that can be moved into quiet bays to ride out the winter. “That’s why I like floaters. You can disconnect them from shore so that they can actually move with the ice.”

How much will this thing cost? Buckle up

The bill for a new boathouse depends on its overall size, the number of storeys, the number of piles or cribs needed, and the decadence of the above-water building materials and interior finishes. “There is no average number of piles 
for a boathouse,” says Joseph Ball. “Some of them have a hundred, and for some you could get away with thirty. 
It just depends on the configuration of the boathouse and the dock.”

Garry Best built a boathouse that ate up $150,000 for the steelwork alone. The house on top cost another $450,000. And while Randy Blain of Randy Blain Construction in Huntsville has seen a few water-garages that topped $1 million, much of that cost was optional 
elegance like $30,000 worth of tile or 
a $50,000 bronze eagle for the roof. “Those ones are way out of my league,” he says with a laugh. “But, with the 
ideal site conditions, you could probably build a pretty nice single-storey, two-slip boathouse for $185,000 to $200,000.” Claude Lord figures that for a “better than middle-of-the-road” single-slip boathouse, whether on floats or steel piles, you could expect to pay $150,000. That figure, of course, doesn’t include the boats.