Guide: Repairing the cottage roof
Weather conditions can do a number on the cottage roof. Here's how to make it watertight
When it comes to the cottage roof, early signs of aging may be hard to spot. Invisible leaks can start rotting rafters long before the first drip hits your head; and an all-too-visible spring dribble from the ceiling may signal ice under the roof, not water coming through.
Inspecting for roof damage
Too many trips onto the roof can cause more damage than it prevents, so combine a regular roof inspection with chimney cleaning or the gutter sweep-out. Avoid hot summer days when asphalt shingles are soft, and cold winter days when they’re brittle. Avoid any roof when it's slippery or when you’re alone at the cottage. Remember shoes with a good grip, ladder tied off at the eaves, insurance premiums paid-up, don’t touch the wires, yadda yadda yadda. And if that sounds like too much trouble, find a reliable local roofing contractor and a darned good pair of binoculars to inspect what you can see from the ground.
If a leak has prompted the inspection, start inside: in the attic or truss space. Follow the damp to its highest point and, roughly, identify the entry area. It’s a rough guess because the water likely took a less-than-direct route through various layers of shingle, underlay, flashing, and sheathing. From inside, you probably won’t see a hole and blue sky. However, if you know, in general, where water is coming in, once you’re on the roof you can have a closer look at the suspect area.
The most vulnerable parts aren’t the regular roof surfaces but the seams, along valleys and dormers, or wherever chimneys, guy wires, plumbing stacks, and vents break the surface. Some such interruptions may be sealed with metal or rubber flashing. Others are simply daubed with black goo that — for lack of a chemistry degree and the patience to nitpick brand distinctions — we’ll nickname tar.
You’re looking for loose or corroded flashing, and cracks or gaps where “tarred-together” seams have separated. “Water infiltration through a newer roof is probably coming through the flashing,” suggests Art Stanfield of IKO Industries, a major asphalt shingle producer based in Brampton, Ont. “I’d look at the chimney first, and then the valleys.” In most cases, flashing will be “shingled” into the roof: overlapped by roofing higher on the slope and, in turn, overlapping the regular roofing down-slope. But even a shingled flashing can fail if wind or ice dams push water up under an unsealed edge.
Stanfield’s choice of words is worth noting. “Infiltration” means water coming through the roof. Water can also condense against the underside of a cooler roof, building up in layers of frost that melt and drip through the ceiling when you heat the cottage in spring. This is not infiltration but a venting problem, something Stanfield insists is the number one cause of roof failure. It is especially critical in cottages where periodic winter visits charge the indoor air with humidity that will condense on any cool surface when you turn the heating down and leave.
Intermittent heating can also exacerbate ice damming, especially in cottages. The cold cottage collects snow on the roof. A weekend visit with a roaring fire and little insulation heats the roof and melts the snow. When the run-off reaches the eaves – which aren’t heated by inside air — the water refreezes, builds up behind this dam, and eventually rises up under the shingles and through the roof. Re-shingling alone won’t solve the problem.
All of which is to say that the roofing material itself may not be the problem. It is, however, the most visible part of any roofing system and the part where signs of aging are most easily seen.
On a metal roof, you’re looking for corrosion — possibly on the panels themselves, but more likely where two different metals might touch: around fasteners and flashings, chimneys, valleys, dormers, plumbing stacks, guy wires, and vents. You might find panels loosened by ice and wind, but you’re more likely to see gaps at the flashings, etc., where “tarred-together” seams have separated.
With asphalt shingles, look for cupped tabs, torn shingles, curled edges, and surface wear as well as the usual suspects: flashing, chimneys, valleys, and so on. Surface wear shows up as bare patches, where the granular coating has come off. The first hint of such aging might be a sediment of little stones in the gutter several years after installation. These are supposed to cover the shingle completely, protecting it from the sun. Sliding ice and snow can wear it off, as can too much foot traffic. Once the aggregate is off, the asphalt begins to break down even more rapidly and, when that cracks, there’s little left but the base material. The most common base is an organic felt — or mat — of wood fibre and recycled paper. The base without its granules and asphalt may be little more than a pulp of old telephone books.
Oddly enough, water is the other natural aging factor for asphalt shingles. Water absorbed by a shingle, starts to break it down, especially during freeze-thaw cycles. Moss and algae on the roof accelerate aging, not directly but by trapping moisture against the shingles. Then there’s the weight factor. By some estimates, an old organic shingle can almost triple its weight with water retention – something to think about if you’re wondering whether your roof can hold another layer of shingles atop the old.
Cedar shakes and shingles suffer some of the same weathering effects as asphalt. Cedar is naturally rot resistant, but wet-dry cycles lead to checking. Water, caught in the cracks or under moss, expands when it freezes and accelerates the deterioration. The good news is that the aging effect of sunlight on cedar — turning it grey — doesn’t have the same destructive effect as it has on asphalt.
If the problem proves to be the roof and not the flashing, it’s time to choose a replacement. With lifetime warranties on some materials and 20-year claims even on cheaper options, it’s not a choice you have to make often. What follows is an update on the more common materials. But before you flip straight to price and longevity claims, remember that success depends as much on installation as the material itself. Asphalt shingles may be more DIY- friendly than rigid metal panels for example, but Art Stanfield of IKO Industries, a major asphalt shingle producer, cautions that “you have to follow the instructions, or get a contractor who can.”
It would seem axiomatic that a roofer should know how to put on shingles, but Dan Trafford, a Rideau Lakes contractor, in his dozen years of repairing cottage roofs, warns cottagers to be wary. “Phone around,” he suggests. “Ask them how long they’ve been in business. And ask for references.” It’s a matter of faith, he says, because most cottagers aren’t there to inspect the job until it’s done, with all the mistakes and shortcuts buried. Which is why you want a contractor who’ll guarantee his work and be around in the future to make good on it.
“Take a simple instruction like nailing tabs below the tar line,” says Trafford. “It’s printed right on the wrapper. But I’ve hired guys who’ve been putting on shingles for 20 years and never read the wrapper. If they put the nail above the tar line, the wind works at the edge and breaks the seal. And the manufacturer won’t honour the warranty if it’s been nailed improperly.”
Start with the selection of a reliable contractor and then worry about what you’re going to put on the roof. If your favourite contractor isn’t trained to install a particular roof, he/she can advise you on the alternatives. Unlike manufacturers, a good contractor can also advise cottagers on local concerns, like how and where to dump several tons of old nail-riddled roofing. It’s no small problem, especially on an island or a steep site where parking a dumpster at the eaves is impractical. Undamaged metal roofing can be reused, and sometimes resold. Old cedar shingles provide a lifetime supply of kindling. While asphalt shingles can be recycled for paving material, small municipalities aren't set up for this and many impose tipping fees on old shingles.
However you handle it, there is a cost for removal and the first question to prospective contractors might be whether to strip the old asphalt or roof over it. Most local building codes will allow two layers of asphalt shingles. Some roofers readily shingle over an old roof because it’s cheaper. Others prefer to start with bare wood; it’s more expensive but eliminates the possibility of repeating any bumpy faults in the original. There’s one other question in the decision to strip or not to strip, and that’s the state of the wooden sheathing, or deck. An older deck, especially on a roof with a history of leaks, may be starting to rot. You won’t get another chance to check it for 20 years or more. Finally, consider covering materials. Properly installed, they will all keep out the water. The differences come down to looks, longevity, weight, ease of installation, ice and snow retention, wind resistance, fire resistance, and cost.
There’s no shortage of new roofing products. The trick is finding new ideas that last as long as their warranty claims. An internet search that turns up as many class-action suits against product claims as it does new products is a sobering message. Look for products and installers who are most likely to be around for the life of the warranty. Check references, ask for proof of insurance, ask the manufacturer for a list of approved or trained installers in your area, and ask the installers about a manufacturer’s record on warranty claims.
Asphalt shingles still dominate 85–90 per cent of the residential market, according to Art Stanfield. He doesn’t hesitate to credit cost advantage for that success. A “square” of economy asphalt shingles, or three bundles, starts at about $50. And application is straightforward enough to invite DIY installation, which is where the real savings come in. It may be false economy if the weekender doesn’t follow instruction to the letter, or drops the ball on the more complicated and more critical business of working around chimneys, valleys, and flashing, but that will be the case with every kind of roof covering.
The basic shingle is a felt mat, saturated with asphalt and coated with granules of crushed rock. The granules are given a coloured ceramic coating before they go on the asphalt. The wide palette of colours gave asphalt an edge in times past when the competition was limited to cedar’s brown turning grey with age, and steel’s grey turning brown with rust.
Asphalt options include a fibreglass mat, tougher than felt but impervious to asphalt. In other words, it can be coated but not impregnated with the stuff. Laminating two mats together can sandwich more weathering asphalt into the shingle, but it costs more and it’s heavier. At the top end are the so-called “architectural” shingles, fat enough to cast shadows at the edges (or have faux shadows coloured along the edges) in order to look more like shakes. In general, the thicker the shingle the more it costs and the longer it lasts.
Longevity is where it gets tricky. First, much depends on roof conditions. As we’ve seen, water retention advances weathering. Where they’re well-shaded and gathering moss, shingles won’t last as long as they might on the sunny, airy side of the roof. A special copper-granulated shingle discourages moss and algae growth, or you can retrofit zinc strips to the roof. It works: Though neither metal will remove existing moss and algae, both will stop further growth.
Then there’s the weather. Philip Steiner had “25-year” shingles installed on his Georgian Bay cottage seven years ago and already finds five or six ripped away each spring. Steiner blames the wind, but his case illustrates the potential gulf between manufacturer, installer, and cottager. The tarred strips across the face of each shingle are hidden under the tabs on the next shingle above. The strips are designed to soften in the sun and seal the two layers together. First, Steiner had his roof installed in October, which might have been too cool for the sun to do its sealing. Secondly, in high-wind areas and cold-weather installations, IKO advises installers to hand-seal each tab with a dab of cement. In high-wind areas, they also call for six nails in each shingle instead of four. And these extra precautions have to be taken during installation, not the next spring when the shingles are flapping in the wind. When installers don’t follow the manufacturers’ advice, any warranty on the materials may be void. The cottager is left to fight it out with the installer.
Ice dams are of particular concern with asphalt. “It’s the biggest complaint in cottage country,” Stanfield acknowledges. The rough surface holds ice on the roof. And if the slope is steep enough to let the ice slide off, it will certainly take some of the protective granules along for the ride. To stop the dam leaks, installers used to apply an impervious ice-and-water shield as an underlay, extending from the eave to 12 inches past the interior wall. Now, six feet is more common, according to Stanfield, and covering the entire roof would be even better. The premium underlay is a bitumen membrane that seals itself to the sheathing and seals around any nails.
Roll roofing is a kissing cousin of the asphalt shingle. Both are fibrous membranes impregnated with bitumen and protected under a granular coating. Roll is solid, not tabbed, more flexible than shingle, and covers with fewer seams. Roll roofing has never been in the good-looks game. But then it doesn’t have to be. Its niche is low slopes. At the cottage, that usually means outbuildings and lean-to additions with short rafter spans that don’t need to shed snow load. Shingles don’t work on these flatter roofs, and looks don’t count where the birds have a better view than passersby.
Unlike shingles, roll roofing has to be carefully and completely sealed when it’s laid down. Each three-foot strip is sealed to the roof deck and to adjacent, overlapping strips. That part has gotten easier. In conventional applications, the adhesive is heated with tar pots and torches. This torch-down application may be safe in the hands of a pro, but weekenders will want to check their insurance for fire coverage in the event of a DIY mishap.
The DIY alternative is self-adhered roll roofing. No stink, no flame, no black footprints on the patio. There are one-ply and two-ply options. In either case, you have to start with a sound plywood deck. One-ply requires a special primer on the deck before you roll out the roofing. With two-ply, you nail the first layer to the deck then peel-and-stick the cap layer.
Bob Sims, customer service manager for Bakor, a “building envelope systems” company headquartered in Mississauga, Ont., says two-ply’s double coverage is a little more foolproof for DIYers. And it carries a 20-year warranty against 15 years for the one-ply. Foolproof? Sims knows at least one first-timer who installed the product upside down, and, like the shingle manufacturers, he stresses the importance of the instructions printed on the packaging. For example, unlike self-seal shingles, roll roofing doesn’t rely on the sun to seal the overlaps, but heat is nonetheless important to get the roofing to lie flat. Sims says 5°C is a minimum temperature for safe application, and 10°C would be better. Unrolling the material ahead of time allows it to “relax” in the sun.
Corrugated galvanized sheets covered farmhouses and barns from the days when looks were less important than steel’s ability to slough off snow and chimney sparks. Now that the old grey ware has been updated with factory-applied colours, steel is taking some of that looks-conscious market share from asphalt, especially in cottage country where steel’s slippery, snow-shedding talent may be worth paying two to three times the price of asphalt.
It can be a mixed blessing for the unwary, however. That rafter-warping weight of snow doesn’t come off a flake at a time but avalanche style. Enough to destroy eavestrough, chimney, deck, or even the odd family car left parked too close to the cottage. While the avalanche solves ice dam problems, you’ll need snow guards (as shown in the photo above) to solve the avalanche problem. The guard, a rake of teeth near the eaves, breaks up the slide into smaller, less destructive pieces.
Steel is still available in long “standing seam” panels, in lengths to fit in one continuous run from eave to ridge. In any colour, they still look like a corrugated steel roof, however. The style upgrade is to smaller steel panels that can be stamped out to look like cedar shakes, like Mediterranean tile, or even — with a granular coating — like asphalt shingles. The smaller panels can also be made of lighter steel than the standing seam; Clyde Pangburn of Bil-Den Home Improvements in Whitby, Ont., a distributor of MetalWorks steel roofing products, offers a 16-gauge panel that weighs just 68 lbs per 100 sq. ft., less than one-third the weight of asphalt. Pangburn claims the panels can withstand winds of 177 km/h and last for 50 years, which is a lifetime in the roofing business.
Dan Trafford finds cottagers more cost-conscious than style-conscious. His clients don’t seem to mind if their standing-seam steel roofs look like steel. “Steel has better results and requires less maintenance than asphalt,” he says. “And for cottage additions, which often have a low-slope roof, continuous-panel steel is the only way to go. Low-slope shingles don’t even exist anymore.”
Like Pangburn and other installers, Trafford stresses the importance of maintenance and service, not one-time installation costs. And that is not to contradict the long-term warranties on the materials. It is a frank recognition that leaks can occur around chimneys, valleys, and flashings no matter what the roofing material might be.
In fact, rigid steel flashings are even trickier to install than pliable, goo-able asphalt. Which is why the cost of a steel installation jumps with the number of hips, valleys, and dormers and why Trafford balks at the very thought of a DIYer trying it. “A lot of steel flashings have to be custom made on the site,” he says. “Then there are the fastenings: roofing screws and neoprene washers. There are special brackets if you want eavestrough. And the steel has to be absolutely square to begin with or you’ll be in trouble at the end.”
Western red cedar shingles cost about $200 a square. And it’s a labour-intensive installation. There may be 1,000 shingles in a square. Each shingle has to be hand-fitted to stagger the joints, and many have to be trimmed at angles in order to fit hips and valleys. Expect labour to add at least another $100–$150 a square, depending on the complexity of the roof. Like any shingle, cedar is ineffective on low slopes (less than 3/12). Even on steeper slopes, shingles may need a good underlay to stop leaks from ice dams and wind-driven rain. Ask the installer to quote on the best full-roof coverage of ice-and-water shield. At about 10 per cent of the total cost it’s probably good insurance on such a big investment.
Traditionally, installers nailed the shingles directly to the sheathing, or to horizontal strapping nailed across the roof at intervals equal to the exposed length of the shingle, giving each row its own nailing strip. The strapping allowed air to circulate under the shingles so that any water infiltration would dry naturally rather than sit there rotting the roof. Unfortunately, the traditional nailing space also made a terrific bat nest. The modern approach is mesh at the openings and latticed airways through the strapping, leading from eaves and gables to a continuous ridge vent.
Or, skip the strapping and use an open mat of synthetic fibre. Installers nail the shingle through the mat, through the ice-and-water shield, and into the deck.
Cedar shingles are also prone to holding moisture and rot faster if they’re tucked under a shady tree or – worse – a spongy patch of moss or pine needles. Zinc strips keep the moss at bay, but leaves and needles should be swept off regularly. Roof maintenance means keeping it clean, which keeps it dry.
Properly maintained, a natural red cedar roof can last 35 years.
Eastern white cedar is about 20–25 per cent cheaper for the material but has about half the lifespan. The biggest attraction of red cedar is the rich natural look. It ages well, fits a cottage landscape, and will never offend the neighours. Shakes, thicker than shingles and usually split rather than sawn, show an even rougher, more rustic texture.
One part of the cedar tradition that has happily fallen by the wayside is the extra cost of insuring a flammable roof. According to Perth insurance broker Richard Schooley, the industry no longer applies the old rating surcharge on shakes and shingles. He attributes the break to a general shift away from solid fuel and falling sparks.
Aluminum shares some of the qualities of steel: Both shed snow and ice, stay put in a wind, and come with long product warranties. Neither metal absorbs moisture and thus neither gains weight on the roof, as asphalt does. The light weight makes aluminum easier to install over some existing roofs. However, aluminum shingle manufacturers, like many steel suppliers, insist on using factory-trained installers. Peter Demchuk of Mississauga, Ont.-based Interlock Roofing, says that the company’s aluminum shingles and tiles resist winds up to 200 km/h. The shingles are fastened with four-way locking clips so “the wind has a better chance of lifting the roof than the shingles,” he states.
Demchuk acknowledges that golf ball-size hail could damage the surface, but he claims that aluminum is superior to steel in holding its colour. The prime attraction of aluminum is longevity, with lifetime guarantees on the material. Eternity has its price, however. Demchuk admits that aluminum is the most expensive product on the market, “maybe three times the cost of cedar. But it’s the last roof you’ll ever buy.”
This article was originally published on November 4, 2003