Can You Pressure Wash Shingles? A Friendly Guide to Cleaning Your Roof
Keeping your home’s exterior clean matters, but pressure washing your shingles calls for caution. It’s effective on plenty of surfaces, but shingles aren’t one of the safe ones.
Pressure washing shingles can cause more harm than good. The high-pressure water strips away the protective granules, leading to premature wear, and if water gets under the shingles, it can damage the roof deck and lead to leaks. That’s why it’s worth looking at alternative cleaning methods first.
Can You Pressure Wash Shingles?
I’ve pressure washed just about everything around my own house over the years, from the basement floor to the siding. But shingles are one thing I’ve learned the hard way to leave alone.
Pressure washing shingles just isn’t a good idea. It might feel satisfying to blast a dirty roof clean, but it can cause water-related damage and structural problems down the line.
Most roofing experts recommend against it altogether. The high pressure can dislodge shingles and cause leaks, which turn into expensive repairs fast. It also damages the shingles’ protective coating, shortening their lifespan and pushing you toward an early replacement.
A soft wash is the better approach. It uses low pressure paired with a cleaning solution to lift dirt and grime instead of blasting it off, and it’s both safer and more effective, without risking your shingles or any installation warranty.
Understanding Pressure Washing
It’s tempting to reach for the pressure washer for everything around the house, shingles included. Before you do, it helps to understand what pressure washing is and how it works.
Pressure washing uses high-pressure water to strip dirt, grime, and stains off surfaces. The washer forces water through a narrow nozzle at high pressure, creating a stream strong enough to cut through even stubborn buildup.
Not every surface can handle it. Pressure washing can damage delicate surfaces like wood, paint, and some roofing materials, shingles included. Check the manufacturer’s recommendations before you start, and when in doubt, call a professional.
Potential Risks of Pressure Washing Shingles
Damage to Shingles
I learned this one the hard way. Years ago, I decided to give it a try myself, and I was a quarter of the way across my roof before I noticed something wasn’t right.
I hadn’t realized the high-pressure water strips off the protective granules, which leads to premature wear, or that it can dislodge shingles enough to loosen or knock them off outright. That’s exactly what happened to my roof, and it cost me another $500 and two days of work to fix.
Water Intrusion
Water intrusion is another real risk. Force water under the shingles and it seeps into the roof deck, leading to water damage and even mold growth, both expensive to fix and the mold potentially harmful to your family’s health.
Decreases Lifespan of Roof
All of this adds up to real financial risk, since pressure washing shortens your roof’s lifespan. The high-pressure water wears down shingles and ages them prematurely.
That leads to leaks, water damage, and costly repairs, or in the worst case, a full roof replacement, one of the biggest expenses a homeowner can face.
Safety Concerns
There’s a safety angle too. Climbing a ladder to reach the roof is hazardous on its own, especially if you’re not experienced with a pressure washer, and wet roofing materials get slippery fast, which can lead to a fall.
The high-pressure water itself can injure you on contact with skin, so wear the right protective gear and take safety precautions seriously if you go ahead anyway.
Alternatives to Pressure Washing Shingles
Is a Pressure Washer Even Needed?
My default is to reach for the pressure washer, but shingles are the exception. If they’re not too dirty or covered in moss, a garden hose and a soft-bristled brush might be all you need.
If you do use a pressure washer, set it to the lowest pressure setting and keep the nozzle at least 12 inches from the shingles.
Soft Washing
Soft washing is the better alternative. A low-pressure spray applies a cleaning solution to the shingles, then a gentle stream of water rinses it off. It’s both gentler on your shingles and more effective at clearing dirt, grime, and moss.
Chemical Cleaning
Chemical cleaning works too: apply a cleaning solution, let it sit, then rinse with water. It clears dirt, grime, and moss without the risk pressure washing carries, though some solutions can harm plants and animals, so pick one that’s environmentally safe.
When Does it Make Sense to Pressure Wash Shingles
Pressure washing shingles is tricky, but a few situations still call for it.
Stubborn stains or dirt that soft washing can’t touch might call for it. Durable shingle materials, like metal or clay, also hold up better against a pressure washer than standard asphalt shingles do.
Either way, keep the pressure on its lowest setting and the spray tip at least 18 inches from the roof. Angle the spray downward, toward the ground, so you’re not forcing water up and under the shingles.
Go slow and careful if you do it yourself, and if you’re not confident you can pull it off safely, call in a professional instead.
Tips for Pressure Washing a Roof
It’s not as simple as pointing and spraying, and it’s generally not advisable. If you’re set on doing it anyway, keep these tips in mind:
- Be careful with the pressure: Shingles are delicate. Too much pressure damages them and causes leaks, while too little won’t get the job done. Aim for a pressure washer set to 1200-1300 PSI with a wide-angle spray tip.
- Use the right cleaning solution: Plain water only gets you so far. Use a cleaning solution made specifically for roofs, and read the label closely for mixing and application instructions.
- Spray downward, toward the ground: keep the spray angle down the roof face, not up it, so you’re not forcing water under your shingles, which can cause mold and damage to your roof decking.
- Protect your plants and landscaping: Cleaning solution and runoff can harm nearby plants, so cover them with plastic sheeting or a tarp before you start. Once you’re done, rinse the area well to dilute anything left behind.
Safety comes first here. Wear slip-resistant shoes, a safety harness, and goggles, and if you’re not comfortable working on your roof, hire a professional instead.
Useful Video from a Professional Pressure Washer
Professional Help for Cleaning Shingles
Shingle cleaning isn’t a job for the faint of heart. It’s tempting to DIY it, but this is one job worth handing off to a professional. There’s no shame in asking for help.
Professional roof cleaners have the expertise and equipment to clean shingles safely and effectively. They rely on low-pressure methods that won’t strip the protective granules or let water seep in and damage your roof.
They also know which chemicals and mix ratios work best. A sodium hypochlorite (bleach) mixture is often sprayed on and left to dwell before rinsing with a garden hose, what’s known as soft washing. Many professionals never touch a pressure washer on a roof at all.
Hiring a professional costs more than doing it yourself, but it’s worth it for a roof that’s properly cleaned and maintained. A thorough wash also restores color and brightness, giving your home an instant facelift.
Cleaning shingles is best left to the professionals, who have the knowledge, experience, and equipment to get the job done right while protecting your roof.
What Time of Year Should Your Roof Be Cleaned?
Timing matters when it comes to roof cleaning. You want your roof free of debris, dirt, and other contaminants that can cause damage and shorten its lifespan.
Spring or fall is the best time to do it. The weather’s mild, temperatures are moderate, and it lines up with when trees shed leaves and debris that build up on your roof.
Skip the rainy season. Wet shingles get slippery and dangerous underfoot, and water can seep in and cause damage. Hot, dry weather isn’t ideal either, since high-pressure water can crack or break shingles that are already brittle from the heat, leading to leaks.
Stick to spring or fall, steer clear of rainy or extreme-heat stretches, and your roof stays clean and well-maintained year-round.
How Often Should You Clean Your Roof?
Finding the right balance matters here, clean enough to maintain your home’s exterior, without damaging the shingles in the process. So how often should you clean your roof?
It depends on a few factors. Live near a lot of trees or the ocean, and you’ll likely need to clean more often, since debris and saltwater build up fast and lead to discoloration and damage. In a dry area with little tree cover, you might only need to clean every few years.
My advice, after years of pressure washing everything else around the house: leave your shingles alone. The risks outweigh the benefits. High-pressure water can lift and crack shingles, drive water beneath the layers, and soak the underlayment and sheathing, all of which lead to leaks and further damage down the line.
It also strips the protective coating that shields shingles from UV rays, wind, and water, along with the granules themselves, aging your roof prematurely and opening the door to water damage and mold.
It might look like a quick fix, but it’s not one worth taking. Hire a professional roofer instead. They’ll have the equipment and technique to get your shingles clean without putting your roof at risk.
