When Bellevue homeowners gaze up at certain roofs, a common question arises: “Why are there rocks on roofs?” This isn’t just a quirky architectural choice – it serves important functions. At Bellevue Roof Repair, we often explain that those “rocks” (usually gravel or stone) are a deliberate part of the roofing system. In Bellevue, WA’s climate (around 42 inches of rain annually, higher than the U.S. average), using gravel on some roofs helps protect homes from the elements. In this comprehensive guide, we explore the reasons for gravel on roofs, discuss roofing do's and don'ts, and highlight common DIY roof repair mistakes to avoid.
The Purpose of Rocks (Gravel) on Roofs
On many flat or low-slope roofs – especially commercial buildings or mid-century homes – you’ll notice a layer of small rocks or gravel spread across the surface. Why is it there? In short, gravel is added for protection and stability. According to roofing manufacturer IKO, gravel on flat roofs serves two main purposes: protecting the underlying roof materials and weighing down or securing the roof against wind. This design is most common in two roofing types:
Built-Up Roofs (BUR or “Tar-and-Gravel” roofs): These roofs consist of layers of felt and hot asphalt, topped with gravel. The gravel layer shields the waterproof asphalt from UV radiation and physical damage. It acts as a protective blanket against sun exposure, hail, and foot traffic. In fact, a gravel topcoat helps prevent the asphalt layers from cracking or degrading under sunlight. This extends the roof’s lifespan and reduces the risk of leaks. (The gravel is often pea-sized aggregate embedded in the top asphalt layer.) Importantly, this gravel also contributes to fire resistance – a thick gravel coating can help a roof achieve a Class A fire rating.
Ballasted Single-Ply Membranes: Modern single-ply flat roofs (like EPDM rubber) sometimes use ballast – meaning loose stones or concrete pavers – to hold the roofing membrane in place. Instead of being glued or nailed, the membrane is laid down and then covered with heavy gravel to keep it from lifting in wind. These large round stones serve as weights, securing the roof while also offering similar protection from UV and impact. In essence, the rocks prevent the roof from blowing away in high winds. This approach has historical precedent: in very windy regions (like mountaintops), builders even used heavy boulders on roofs to hold down materials. For example, in parts of the Swiss Alps traditional homes had rocks on the roof to keep shingles from lifting in strong gusts. In Bellevue’s milder climate we don’t use giant boulders, but the principle of ballast remains in flat-roof design.
What about ordinary pitched roofs? Typical sloped residential roofs (e.g. those with asphalt shingles) don’t have visible loose rocks, but they do rely on mineral materials for protection. Asphalt shingles are topped with tiny crushed stone granules – essentially very small “rocks” embedded in the shingle. These granules give the shingle color, but more importantly they protect the asphalt from UV rays and add fire resistance. Without the granule coating, asphalt shingles would deteriorate much faster under sunlight. (This is why seeing lots of granules in your gutter is a warning sign – your shingles may be aging.) It’s worth noting that asphalt shingle roofing is extremely common (used on about 4 out of 5 U.S. homes), so almost every homeowner has “rocks” on their roof in one form or another.
A roofing contractor spreads pea gravel on a flat roof. The gravel layer protects the underlying asphalt and adds weight to hold the roof membrane down in wind.
In summary, those rocks on roofs are there by design. They shield the roof from weather, sunlight, and impact, help anchor the roofing materials in wind, and even contribute to insulation and drainage. A gravel-covered flat roof can dissipate heat better (the stones absorb and release heat), and they help water drain by preventing puddling in any one spot. The gravel can also catch floating debris like leaves, stopping them from clogging drains. Far from being mere “filler,” the stone layer is a critical component of a well-built roof system.
Common DIY Roof Repair Mistakes (and Why to Avoid Them)
Knowing that gravel plays a vital role, it’s clear that handling it improperly can cause problems. Unfortunately, well-intentioned homeowners sometimes attempt fixes that do more harm than good. Let’s highlight some common DIY roof repair mistakes and pitfalls – the roofing “don’ts” – especially relevant to gravel roofs and shingles:
Removing or Displacing the Gravel: A classic mistake is sweeping away gravel to address a leak or install something, and then not replacing it properly. Remember, that gravel is protecting your roof. Leaving sections of the roof uncovered (bare) exposes the waterproof layers to UV damage and speeds up deterioration. Don’t ever permanently remove the rocks on a gravel roof as a “solution” – you’d be stripping away critical protection and inviting leaks.
Improper Sealing and Patching: Another pitfall is trying to seal a leak with the wrong materials. For example, slathering on general hardware-store caulk or roof cement without cleaning the area or matching the roof type can lead to improper sealing. Using the wrong sealant or applying it incorrectly may trap moisture or fail to adhere, resulting in a leaky mess once the next rain comes. Do use only materials compatible with your roofing (e.g. specialized asphalt cement for BUR, or manufacturer-approved patch kits for single-ply membranes). Don’t just slap on silicone sealant or tar as a cure-all – improper sealing is a leading cause of continued leaks after DIY repairs.
Using Incorrect Fasteners or Materials: We have seen cases where people use nails or screws that puncture the roof membrane, or try to “improvise” with materials not meant for roofing (like using sheet plastic weighted with bricks). These quick fixes can create new holes or fail under weather stress. Don’t use makeshift materials that aren’t designed for roofing applications. Every component on a roof – from the type of gravel to the nails – is carefully chosen by professionals for compatibility. For instance, using a standard nail instead of a roofing nail with a proper cap can lead to water intrusion. Do follow roofing do’s and don’ts as advised by experts: use the right materials in the right way, or call an expert if you’re unsure.
Neglecting Safety Precautions: Climbing onto a roof is dangerous, period. One of the biggest DIY mistakes is underestimating the risk. Working at heights without proper safety equipment (harness, sturdy ladder, non-slip footwear) can lead to severe accidents. Unfortunately, falls are all too common – every year about 500,000 people are treated for ladder-related injuries in the U.S., and 300 die from those falls. Roofing work is even recognized as one of the most dangerous jobs (with falls being the leading cause of fatalities). We strongly advise against inexperienced homeowners going onto their roof. A slip on loose gravel or a misstep on a steep shingle roof can be life-threatening. Safety is a non-negotiable “don’t” for DIY: if you aren’t trained and secured, don’t attempt it.
Overlooking Underlying Issues: A DIY repair might address what’s visible – say, re-cementing a loose flashing or replacing a missing shingle – but miss deeper damage. One common mistake is patching the symptom but not the cause. For example, you might seal a crack in the roofing felt, but if that crack was caused by a rotting roof deck or poor drainage, the problem will recur. Professionals inspect for hidden issues (wet insulation, structural rot, etc.) that DIYers often don’t catch. Don’t assume the first obvious issue is the only issue.
Roofing Do’s and Don’ts for Homeowners
To sum up the best practices, here are some quick roofing do’s and don’ts to keep in mind:
Do perform regular roof inspections (or have them done professionally) to catch issues early. Check that gravel on flat roofs is evenly distributed and no bare spots have formed after storms. For shingle roofs, look out for granule loss, cracked shingles, or loose flashing.
Do keep your roof clear of excessive debris. While a gravel layer will trap some leaves (by design), you should still carefully remove large piles of leaves or branches, as they can cause water backup. Remove debris gently to avoid dislodging the protective gravel.
Do prioritize safety above all. If you must go onto your roof, use a sturdy ladder with someone stabilizing it, and wear proper gear. Maintain three points of contact on the ladder at all times and never work on a wet or icy roof.
Don’t attempt major repairs alone if you’re not experienced – especially anything involving structural elements, extensive re-roofing, or complex leak diagnostics. Mistakes can lead to greater damage or voided warranties.
Don’t use pressure washers or aggressive methods to clean a roof. For example, don’t power-wash a shingle roof; it can strip away the granules that protect it. Likewise, don’t try to wash away the gravel on a flat roof – you’ll only hurt the roof.
Don’t ignore small problems. A tiny leak or a few missing gravel pieces might seem minor, but in our rainy Bellevue weather, even a pinhole can let in significant moisture. Over time, that can rot wood, ruin insulation, and lead to costly repairs. It’s estimated that the average water damage insurance claim is over $11,000, so preventing water intrusion is well worth the effort.
By following these guidelines, homeowners can avoid the most common pitfalls. The key takeaway is that while basic monitoring is wise, significant roof work is best left to professionals who know the roofing do’s and don’ts inside out.
Professional Roof Repair vs. DIY
It’s understandable that homeowners may consider DIY repairs to save money or time. However, as we’ve outlined, the roof is a home’s first line of defense and mistakes can be costly. Here’s why professional help often outweighs DIY:
Expertise and Proper Fixes: Experienced roofers (like our team at Bellevue Roof Repair) know how to fix the root cause of an issue, not just the surface symptoms. We ensure that repairs are done with the correct technique and materials, preserving the roof’s integrity. This includes correctly reapplying gravel on a flat roof after repair, properly sealing around vents and skylights, and using compatible patches for the roofing membrane. A professional repair comes with the benefit of trained eyes spotting other potential trouble spots while up there – saving you future headaches.
Avoiding DIY Traps: Professionals avoid the common DIY errors by default. For example, we will never use the wrong caulk or forget to secure a flashing. Unfortunately, we often get called to fix DIY roof repair mistakes made by well-meaning owners. In many of those cases, the initial DIY attempt not only failed to solve the problem but also made the repair more complex than it would have been. Hiring a pro in the first place can actually save money in the long run, because it prevents compounding damage.
Safety and Insurance: Professional roofing contractors are trained in safety and carry insurance. When we go up on a roof, we use proper fall protection and equipment. This eliminates the risk to you. It’s worth noting that if a homeowner falls or gets injured doing their own roof, homeowner’s insurance may not fully cover that kind of accident – a sobering thought given the statistics on ladder falls. Professionals also carry liability insurance to cover any accidents or unexpected damage, giving you peace of mind.
Quality Materials and Warranty: A reputable roofing company uses high-quality, vetted materials. For instance, if a section of a gravel roof needs new bitumen and aggregate, we’ll use commercial-grade products that match the existing roof. We also stand behind our work with warranties or guarantees. DIY fixes typically have no warranty – if it leaks again, it’s on you. With professional repair, if an issue persists, you have recourse to get it corrected at no extra cost.
Local Knowledge: Being local to Bellevue, WA, we’re familiar with the specific weather patterns and building codes in our area. We know what 42 inches of rain a year means for a flat roof’s drainage, or how occasional windstorms can scatter roof gravel if not properly embedded. This local expertise means we can tailor solutions that are ideal for our Pacific Northwest climate. A generic online DIY tutorial might not account for our region’s heavy winter rains or moss growth tendencies. Bellevue Roof Repair will ensure your roof is ready for our weather.
In sum, while there are some roof maintenance tasks a careful homeowner can do (like cleaning gutters or replacing a very small area of shingles), many aspects – especially anything involving gravel roofs, major leaks, or safety risks – should be handled by professionals. The cost of a pro repair is often a fraction of the cost of interior water damage, medical bills from a fall, or the frustration of a failed DIY attempt.
FAQs: Rocks on Roofs and Roofing Repairs
Q1: Is it normal to have rocks on my roof, and what exactly do they do?
A: Yes, if you have a flat or low-slope roof designed for it, a layer of small rocks or gravel is completely normal and intentional. The gravel protects the roof from UV rays, hail, and weather damage, and in some systems it weighs down the roofing materials to prevent wind uplift. In other words, those rocks are working to keep your roof durable and leak-free. They are not just for looks – they prolong the life of the roof. If you have a traditional pitched roof with shingles, you won’t see loose rocks, but the shingles themselves contain mineral granules that serve a similar protective purpose.
Q2: Should I remove the gravel from my flat roof or can I replace it with something else?A: No – you should not remove the gravel permanently. The gravel is a crucial part of the roof system. Taking it off would expose your roof to sun damage and could invalidate the roofing design. If you are concerned that the gravel layer looks thin or has bare spots, the best course is to call a professional. An expert can redistribute existing gravel or add compatible gravel if needed. Never replace it with random rocks from your yard; roofing gravel is specific in size and weight. In short, keep the gravel in place. It’s protecting your home. If it’s been displaced (for example, after a repair or a storm), have it correctly re-installed rather than leaving the roof surface bare.
Q3: What are the risks if I try to fix my roof myself (DIY)?
A: DIY roof repairs come with significant risks. The first risk is safety – climbing onto roofs is dangerous. Falls from ladders and roofs cause hundreds of thousands of injuries each year. Professionals use proper safety gear that homeowners typically don’t have. The second risk is making the problem worse or voiding warranties. Common DIY mistakes include using the wrong materials, poor sealing that leads to leaks, or inadvertently damaging the roof’s protective layers. For example, using a pressure washer can strip off shingle granules, or failing to reseal a gravel roof properly can invite water intrusion. These mistakes can result in costlier repairs down the line. Finally, any temporary savings from DIY can evaporate if a small leak turns into major water damage – which is expensive to remediate. That’s why we recommend being cautious: handle minor cleaning or inspections if you’re comfortable, but for any actual repair, consider hiring a qualified roofing professional. It’s safer and more cost-effective in the long run.
By understanding why there are rocks on roofs and respecting the do's and don'ts of roof maintenance, Bellevue homeowners can make informed decisions about their roofing care. Remember that your roof is a system designed by experts – each element (even a simple gravel stone) has a purpose. When in doubt, Bellevue Roof Repair is here to help maintain that system, ensuring your roof remains a reliable shield over your home for years to come.
Check out this guide on safe and effective DIY roof repairs here before starting your next project!