MOSS ATTACK! How Can I stop Moss Growing on My Roof?

May 7, 2021

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How can I stop moss growing on my roof? If you’re a homeowner, you might find yourself asking that question at least once over the lifetime of homeownership, and more often if you live in the tropics or anywhere with high humidity levels!

A soft-bristled outdoor brush can remove most moss growth from roofs, while over-the-counter and DIY moss treatments kill spores and growth, to keep moss from returning. Powdered oxygenated bleach is also an excellent solution for stopping moss and cleaning roof surfaces!

Moss is not something to ignore as it can cause roof materials to degrade, shortening their lifespan and leading to otherwise unnecessary roof repair and replacement costs. The sooner you tackle growing moss, the less damage it will cause and the easier it will be to remove as well!

growing moss on a roof

Check out some tips on how to stop moss growing on a roof and clean away moss, mold, mildew, algae, and other residues and debris. This information will ensure your home’s roof is always clean and pristine and protected from damage, and in good condition over the years.

How to Stop Moss Growing on a Roof

The first step to stopping moss from growing on a roof is to remove any moss that’s already covering shingles or tiles. You’ll then want to saturate the roof with a moss killing agent or cleanser and rinse the roof clean. Note a few specific tips on how to get this done for your home:

  • First, ensure your safety when on the roof. Invest in work boots or sturdy shoes with nonslip soles, safety glasses, and thick rubber gloves. It’s also helpful to use a safety rope designed for roofing contractors, to avoid falls and injuries.
  • You’ll also need a proper extension ladder or, ideally, a lift or platform that allows easy and safe access to the roof. If you use a ladder, ensure it’s in good condition, have a helper hold it for you while climbing, and always practice safe ladder use.
  • Choose a soft-bristled brush meant for cleaning roofs. Never use a stiff-bristled brush or other tools on the roof even for thick moss and debris, as these can damage shingles, tile, flashing, and other materials easily.
  • You’ll need to rinse the roof thoroughly; if your garden hose doesn’t reach the roof’s surface, you can typically buy an extension with the length needed for roof access.
  • Cleansers are best applied with a spray bottle, so choose one with a large capacity and nozzle, to make quick work of saturating moss spores and growth.

Start by hosing off and brushing the roof

hosing off the roof

Your first step in removing moss from the roof is to hose off as much growth as possible. Start from the top of the roof and work your way downward; never spray upward, from the edge of the roof, as this can loosen shingles and tiles.

Once you’ve hosed off as much moss as possible, gently brush the rest of the growth. Again, work from the top of the roof and move downward, using firm but gentle motions. Never scrub or scrape the roof roughly, as this can damage clay tiles, strip granules off shingles, or otherwise lead to costly repairs!

Add treatments where needed

Over-the-counter moss treatments are excellent for killing spores and roots, helping to prevent moss from returning. Moss B Ware and Wet & Forget are two excellent products that work well for killing moss; apply them as directed on their packaging.

adding treatment to roofs

You can also add any of these everyday products to 2 gallons of water and apply them to your home’s roof, to kill moss and remove dirt and grime at the same time:

  • Eight ounces of dish soap (without lotion)
  • Two cups white vinegar
  • One pound oxygenated bleach (powdered)
  • Two cups chlorine bleach

Remember to mix these well in water before applying. Allow the mixture to soak the moss for about 30 minutes and then brush away any growth.

Give the roof one last rinse to remove as much moss as possible. Note that it might not all come off, but your treatments should work to dry up moss spores so it then falls away from the roof within a day or two.

Stopping Moss From Growing on the Roof

Zinc and copper are both toxic to moss and can help prevent it from growing. Most hardware and home improvement stores will have zinc and copper strips meant for roof installation. Add these just below the top ridge using roofing nails or screws with rubber washers.

When it rains, these metals will leech onto your home’s roof in amounts just sufficient for keeping moss and other growth at bay. A professional roofer can also apply these strips for you if you prefer to stay off the roof! Once installed, you should see at least a significant decrease in moss growth over the years.

Note, too, that sunlight and fresh air are both natural enemies of moss, mold, mildew, and algae! Trim back overhanging tree branches and keep the roof clean of storm debris and other residues, to increase sunlight exposure and fresh air and help keep moss growth to a minimum.

Should I Clean Moss Off My Roof?

technician performing soft wash roof cleaning in Cape Coral

Moss is not just unsightly; it’s also damaging to roofs. Moss eats away at wood, asphalt, and other roofing materials, and works its way underneath tiles, shingles, and flashing. The thicker the moss, the more likely it is that you’ll lose roof pieces during a storm or in high winds.

Pulling at shingles and tiles also means exposing the roof underlayment and decking to water and direct sunlight. These can also degrade those materials, increasing the risk of cracks, leaks, and gaps in the roof. The longer you ignore moss, the more damage your roof is likely to suffer, so ensure you clean it as the first sign of moss, mold, and other contaminants.

What to Do with Dead Moss

Some species of moss can reappear after having been dried out for months! If it’s been especially dry in your area, moss on your home’s roof might appear dead; moss might also appear dormant after the winter months.

However, this doesn’t mean that the moss is no longer damaging to your home’s roof. In many cases, that moss will start to regrow after the first rainfall, or once the air is saturated with humidity. Rather than ignoring this issue and assuming that dry moss is dead and not a threat to your home’s roof, wash it away or have a contractor clean it as soon as possible.

Why Am I Getting Moss on My Roof?

Moss is actually a type of plant that gets moisture through its leaves and not roots. Moss spores become airborne in high winds or get scattered by birds and other animals, and then end up on your home’s roof. Those spores then begin to absorb moisture and grow.

cleaning moss off a roof

Since moss loves cool, damp environments, it’s more likely to grow in areas of high humidity and on roofs shaded by tree branches and other obstructions. Moss also absorbs rainwater easily, so it thrives in areas with heavy rainfall. While you obviously cannot control your area’s weather condition, you can remove moss at the first sign of growth, to help keep it from spreading.

Natural Moss Killers

Bleach, household dish soap, and vinegar all kill moss naturally and can also help remove other dirt and grime from your roof! Baking soda also helps kill moss spores and roots and will choke its leaves so it cannot get the moisture needed to grow.

Ensure you dilute these products in water and apply liberally to moss during the cleaning process. If needed, wait a few days for the products to dry up lingering moss and then apply again, for a thorough clean.

Getting Rid of Moss Without Using Chemicals

While bleach is an excellent substance for killing moss, mold, and other growth on the roof, its smell can be somewhat overpowering and bothersome, especially for those with asthma and other sensitivities. It can also be difficult to enjoy your outdoor space if the air smells of bleach and other cleansers!

cleaning a metal roof with moss

If you want to avoid bleach, try sprinkling baking soda onto the moss and then gently brushing it into the roof surface. The alkalinity of baking soda can often kill growing roots and spores, while also gently dislodging moss from shingles and tiles.

Zinc and copper strips are also excellent for preventing moss growth, as said. These strips don’t use chemicals, emit fumes or pollutants, or produce any odors! If you do decide to use these strips, ensure you have them inspected every few years for a needed replacement.

When mixing bleach solutions for addressing moss on your home’s roof, you can also add a few drops of essential oils to the mixture. Peppermint, rose, and other such oils can help reduce chlorine smells, ensuring a more comfortable environment on your property.

Pressure Washing Moss Off the Roof

pressure washing moss of a roof

When you see moss, mold, mildew, algae, and other debris on your home’s roof, your first instinct might be to rent a pressure washer and blast away all that unsightly residue! However, a homeowner should avoid pressure washing a roof. Improper power washing techniques might pull shingles and tiles from connectors, dent or crack roofing materials, and blow granules off asphalt shingles.

A professional power washing contractor is actually an excellent choice for removing moss and other debris from your home’s roof. Soft wash pressure washing uses specialty cleansers that dissolve moss and mold spores so that a low-pressure rinse can then remove that growth from the roof without damage.

Soft wash roof cleaning by a professional power washing contractor can also clean away thick dirt, grime, mud, dust, soot, and other debris. Washing away that damp residue means less risk of moss and mold returning over the years.

Can Moss on Roofs Cause Leaks?

Roof shingles and tiles are designed to encourage water runoff from a roof’s surface. These materials protect roofing underlayment, decking, and other layers that protect a home’s framing and interior spaces from water.

moss growing on slate roof shingles

When moss develops on a roof, it can grow underneath shingles, tiles, flashing, and other materials, pushing these upward and away from their connectors. As it does, it creates gaps between shingles or tiles and the materials under them.

Those gaps let water seep into those other roofing layers, risking damage including cracks, tears, and holes. Your roof can then eventually leak and cause water damage to your home’s interior. To avoid this risk, address roof moss, mold, mildew, algae, and other residues at the first sign of growth!

Cost to Remove Moss From a Roof

Most power washing contractors charge by the square foot, and prices will average between $0.20 and $0.70 for roof cleaning. Some power washing professionals might evaluate your home’s roof and then charge a flat rate, usually between $200 and $400 or more for roof washing.

Note that cleaning moss usually requires more work and added cleansers, so expect to pay at the high end of these averages the more moss, mold, mildew, algae, and other debris covering shingles and tiles. Roof washing contractors might also charge more for especially seep roofs, for working around lots of obstructions such as skylights, and for especially filthy roofs that haven’t been cleaned in years!

cleaning off a roof professionally

While you might hesitate at paying a few hundred dollars for moss removal and roof cleaning, consider the cost of roof repairs if you should neglect this service! Replacing shingles and decking, patching leaks, and other fixes can often run into the thousands of dollars and will typically just get costlier the longer you ignore needed roof cleaning and moss removal.

A pressure washing contractor can also provide expert gutter cleaning, which also protects a home from water damage. Clogged gutters let rain and snow back up onto the roof, where that moisture is absorbed by shingles, decking, and other materials. Rain washing over gutter sides also collects around the foundation, risking damage to its concrete!

ProClean Pressure Washing Cape Coral is proud to offer this information to our readers and we hope it helped answer the question, how can I stop moss growing on my roof? If you need moss or any other residues cleaned from your roof, or are in the market for expert power washing, rely on our trusted Cape Coral pressure washing contractors! We have over 20 years of industry experience and stand behind all our work with a full guarantee. To find out more, give us a call today.

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