Houseworks: Taking care of roof and deck duties

Lichen growth like this will shorten the life of most roofs, but it can be removed and prevented.  Photo by Lois Sampson 

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Cleaning a cedar roof 

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Q How can I get lichen off my cedar shake roof? I’m a recent widow on Vancouver Island and don’t know who to turn to and what they might recommend. The roof is over 10 years old but only started to grow lichen last year.  

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A Sorry to hear about your loss, and I’m happy to help with your situation. The photos you sent were helpful. 

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Cleaning lichen off cedar shake/shingle roofs is somewhat different than with asphalt shingles because cedar is soft and easily damaged. Here’s what I’d recommend for a procedure: 

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1. Have the roof sprayed with an oxygen bleach solution or something designed to kill rooftop growths. You want something that’s completely non-toxic to plants, people and animals but kills lichen. 

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2. Let the solution sit for half an hour or so, ideally on a cloudy, cool day so the solution doesn’t dry too quickly. 

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3. Lightly brush the roof downwards with a long-handled nylon brush. Don’t scrub upwards on the roof slope.  

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4. Rinse the roof with plenty of clear water. 

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5. Repeat the process if any lichen remains. 

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6. Install copper or zinc strips underneath the cap shingles on the peak so about an inch or two of metal is exposed, and every 15 feet down the slope. This releases small amounts of dissolved metal into water that runs down the roof, preventing or limiting future moss and lichen growth. 

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The key in all this is to find the right kind of person to do the job. Roofing contractors aren’t typically the best for this since they’re focus is usually replacing roofs, not applying the kind of careful and delicate attention you need. A better option would be an experienced handyman; someone who can take direction from you and not try something on their own. Handymen (could be a woman) generally charge by the hour, so this will give you a better idea that you’re not being taken advantage of. Those large quotes you mentioned in your note ($7,500 to $15,000) seem quite ridiculous and over-done. 

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How large is your house (length x width roughly)? Is the roof too steep to walk on unaided, or can people walk around up there just on their feet?  

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Ballparking the job, I’d say it might take three to five days of work, eight hours per day @ $40/hour = $960 to $1,600.  

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Have you searched for handymen in your area? You’d want one with experience on roofs, and also you should ask for and check at least three references. Some of the best home maintenance results come from experienced handymen precisely because they’re generalists. And home maintenance is often about doing things beyond just the immediate main task that one trade knows, pivoting to new tactics when the unexpected arises. 

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I’ve had great results personally with a product called Wet & Forget Moss Mold, Mildew, Algae Stain Remover.  

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After application, just wait and see what happens. It’s possible that the lichen will die and eventually wash off with rains and such. If not, then scrubbing gently with a long-handled brush from a ladder will help. You want to avoid having anyone walk on those cedar shakes if at all possible. If walking up there is necessary, have your worker wear soft-soled shoes and keep walking to an absolute minimum.