Cedar Shake Roofing and Ice Dams
Do you have cedar shake roofing, or are you considering it? If so, I’ve written this for you.
Cedar shake roofs look great, but the bad news is you’ll probably pay much more for ice dam removal than your asphalt-shingled neighbors might. That’s because often it takes longer to remove ice dams on cedar shake roofs.
Why does ice dam removal take longer on cedar shake roofs? Because it’s extra slippery, and often times we have to work from a ladder.
Stepping onto a cedar shake roof is like stepping onto a thousand banana peels. It’s more dangerous. Because we often times can’t stand on the roof safely (even with a rope & harness), we’re forced to do our ice dam removal from a ladder, leaning against the house. Removing ice dams from a ladder almost always takes longer, and sometimes much longer. You constantly need to move the ladder a few feet down the overhang, and you’re not able to work from the top down as you can when you’re standing on the roof, above the ice dam. Because hot water – the byproduct of steam and ice – runs downhill, standing above the ice dam (having gravity on your side) can help you melt ice much more quickly. When you’re fighting gravity (working from a ladder), ice dam removal can take much longer.
It doesn’t help that ice becomes part of each shingle. When ice grabs onto an asphalt-shingled roof there’s not much for it grip to: just the surface of the shingle itself (usually with granules), and the small lip between each of the shingles (the overlaps). Ice freezes onto an asphalt roof.
Ice freezes into a shake roof. With cedar shake roofs you’ve got thick, porous wooden shingles. Every shingle offers countless pores for ice to stick into, not to mention the much-thicker lip between each shingle. Also, wood is absorbent. If your bath-time rubber ducky is made of wood, he’ll leave your tub heavier than he entered. The same is true of your shake roof whenever it’s exposed to water – even if it’s been sealed.
The ice eventually just “pops” right off of asphalt shingles. That’s why we like to remove ice dams a section at a time – with our “chunk-cutting” method. Not so with wooden shingles, though. The ice just hangs onto the building like Bruce Willis near the end of Die Hard. On a shake roof, even a pea-sized piece of ice can stick on for long enough to make your ice dam removal expert most likely to melt the ice with his tears. On a shake roof, you can’t often remove chunks of ice, and instead you’re most often times forced to melt away every last piece of ice.
We have to go extra slowly, too, so as not to fray the wood and make your home resemble a thatched hut.
One more reason to think twice about a cedar shake roof: because wood is porous, it gets dirty and weathers very quickly. What’s that got to do with ice dam removal? Well, as our steam melts the ice off of your roof, the steam also cleans and brightens the wood. Those freshly steam-blasted areas will have less grime, and will appear lighter in color. But because our job is to remove the ice dams rather than clean the whole roof, some parts of your cedar shake roof will appear cleaner and lighter than others. Your cedar roof make may very-well look like an wet calico cat when we’re finished.
Why ice-covered cedar shake roofing leaks so much.
Even if the costs of extra-long ice dam removal don’t deter you from installing cedar shakes on your roof, perhaps the near-certainty of a leak will.
Asphalt shingles form a reasonably tight seal. The shingles are thin, heavy (much heavier than they look), and lie almost perfectly flat. Water doesn’t seep in easily. In some cases it’s even possible to get an ice dam and not get leaks, even if you don’t have proper ice & water shielding.
The thinness, heaviness, and flatness of asphalt shingles help stave off water. Cedar shakes have none of those properties. Shakes are not truly flat. Look closely and you’ll notice they’re slightly cupped. You can put one on top of another and see right through them. There is no natural seal between each layer of shingles. Cedar shakes are very light, too. Cedar shake roofs operate on the assumption that all the water will run off. When an ice dam forces the roof to hold water, the small gap between each shake will invite water onto your roof deck, and eventually right into your home.
In a nutshell: cedar shake roofs are pretty, but they may not be worth it.
If you don’t have a cedar shake roof already, save yourself the heartache and do not get one. I’m not saying to build your home around the possibility that you might get ice dams. The larger issue is that cedar shakes simply aren’t the right kind of roofing for a wintry climate. But if you must have a cedar shake roof, then do yourself a massive favor and absolutely insist the the entire roof deck is covered with premium ice & water shielding.
If you do have a shake roof already (and have probably run into issues with ice dams and leaks), you may save yourself some money and anguish if you switch to an asphalt-shingled roof with complete ice and water shielding. Even better yet, a metal roof! These roofing options will cost you less than all the water damaged property and ice dam removal costs you may incur as a result of your shake roofing.