Will Moss and Lichen Affect My Slate Roof?

Overall, moss and lichen will NOT adversely affect the integrity of your slate roof but there is one caveat to that answer.

Moss growth primarily occurs on the southern slope of your roof but can certainly grow on other slopes, just not usually to the same degree as the southern slope. We do not believe moss has any negative effects on the integrity of your slate tiles but on a low slope it can impede the water flow which can lead to leaking.

A leaking roof can be fixed or avoided by professional moss removal. If leaking has already occurred, offending slate tiles need to be removed, cleaned/scraped, and reinstalled after proper preparation including new sarking under the battens. Moss removal can be accomplished through scraping, pressure cleaning, and/or chemicals but keep in mind that all methods are temporary since regrowth will eventually occur.

Provided your roof has steep enough pitches to prevent these natural growths from impeding water flow, removal is simply a matter of personal choice. Many people prefer the moss and lichen as “character building” qualities that money can’t buy and only time can add. Architects will often even specify mossy reclaimed slates, especially with an extension to match the existing slate roof and home.

Do Hail Storms Damage Slate Roofs?

You obviously want the answer for your roof to be no but we have seen many cases recently where the answer is yes. The determining factor, not surprisingly, is the quality of the slate.

Melbourne has experienced some very intense and damaging hail storms in recent years. Quite a large number of older and softer slate tiles did not fare well in these storms. Damage ranged from only a few perforated or snapped tiles to a need for complete replacement of the entire roof, and everything in between.

There were some instances we inspected where the roofs were relatively new but poor quality tiles were used and the damage was considerable, requiring complete replacement of the roof. Overall though, roofs with concrete or terracotta seemed to sustain more damage than slate roofs did.

There is definitely good news for everyone choosing good quality slate for their roofing. ALL of the roofs we inspected that had good quality slate, both new and old roofs, were completely unfazed. They were undamaged, water tight, and worry free. You could easily say this makes a strong case for choosing good quality slate roofing installed by master slaters.

Can You Walk On Slate Roofs?

The best answer to this question is no. That answer should include other tradesmen like house painters, satellite dish installers, etc.

The problems with walking on slate roofs include both safety concerns and damage to the roofing material.

Safety Concerns

Steep pitched roofs are both difficult and dangerous to walk on. The risk of personal injury is significant. It ought to go without saying but we’ll mention anyway that a slate roofing professional is much cheaper than a hospital or funeral home.

Even lower pitched roofs at 28 degrees or less still pose significant hazards. Melbourne roofs are prone to moisture, moss, and other naturally occurring growths that are harmless to the roof but make the surface slippery. Slippery + slope + gravity = quick trip to the ground.

Roofing Damage Concerns

The quality and age of the slate roofing material is a major determining factor in how well the roofing holds up under human feet. Good quality slate holds up well under everything Melbourne weather can throw at it, but is doesn’t necessarily hold up to foot traffic. Lesser quality slate most definitely caves under pressure.

Without the knowledge a slate roofer has for being on the roof, any attempts to walk on the roof can and probably will result in snap, crackle, pop, perforation, or even dislodging of the slate tiles, along with other potential damage.

Here’s a great way to put this in proper perspective: In 10 minutes, an inexperienced person can do more damage to your slate roof than 100 years of nature could!

Why Do So Many “New” Slate Roofs Fail?

The answers to that question probably aren’t going to offer very many surprises, but the one factor that does surprise people is how quickly a new slate roof can fail. It can happen in as little as 3 years! Most owners of a bad slate roof learn that lesson the hard way but if you’re one of the few people who ask this question beforehand, congratulations.

This is going be less about why a slate roof can fail so you can avoid having it happen, or worse, having it happen again if you’ve already been burned. Knowing why they fail does equip you to avoid the heartbreak and expense of a failure.

Not all slate is created equal

In other words…quality. Slate is a natural product. Many people falsely assume that because slate is mined from the earth, it is essentially all good. That is very incorrect. The facts are that slate varies widely in its resistance to moisture and water absorption, delaminating, its stability and longevity, and its overall suitability for being used on your roof.

Another factor that is not helping your situation is that testing slate quality is voluntary so a great deal of slate being sold on the market isn’t tested, or it is only tested for a standard used to mislead uninformed buyers. The downside for natural products is they don’t have the same accountability that applies to the manufacturers of manmade roofing products.

There are stringent testing standards like the French NF30 which is generally regarded by experts as the most rigorous testing standard in the world. Having slate tiles that pass tough testing standards may appear to make them cost more, but the reality is, if you don’t have the right slate quality installed, you’ll just spend money on better quality later, and that’s the real expensive option.

Poor quality workmanship

Again, no surprises as we state the obvious, but unqualified slate roofers are at least as bad as poor quality slate material. We dedicated much of our previous post (and other posts) into some basic rules for qualifying a good slate roofer, but because so many new slate roofs in the Melbourne area have suffered the consequences of poor quality workmanship, we can’t overemphasize how important this is.

Melbourne is subject to torrential downpours. That’s what makes slate such a great choice when quality tiles are properly installed. But improperly installed, all the benefits get cancelled out. Melbourne is also subject to some high velocity winds. Properly installed, your slate roof is like armor plating. But poorly installed your slate tiles can become dangerous projectiles posing a serious threat to persons and property.

Climbing on the roof

Slate roofing will withstand everything nature can throw at it better than any other roofing material. People on the slate roof does not fall under the nature category. You should consult with a slate roof professional before anyone climbs on the roof. A satellite dish, skylights, or a better view are not worth ruining your slate roof for.

How to Tell if You Need a New Slate Roof

Waiting until the obvious signs appear like ceiling stains, buckled walls, and chunks of wall and ceiling material falling would be the worst advice for detecting the need for a new roof. Visible damage means the things you don’t see have been a long time in the making and the “maturity” of that damage will cause deep wounds in your economic situation when you’re faced with fixing it.

Like pretty much anything else in life, early detection of the need for new slate is your best defense and least expensive option. If you suspect that your old slate may be getting tired, you can have a professional inspect it for you, but inspecting it yourself is an easy and viable option if you are able to access the underside inside the ceiling cavity.

Yes, it’s the underside of your slate tiles that tells the real story. Failing slate tiles will exhibit easily identifiable characteristics, including:

  • Delaminating, flaking, and peeling
  • White, powdery surface formation
  • Softness

Those visible signs are easy to see. You may even observe color variations that signal moisture penetration. The surest sign of leakage in the near future is softness. Good slate tiles will be firm and hard.

To check for softness, a standard screwdriver is an easy test. Apply a firm pressure as you drag a screwdriver across the underside of your slate roofing. If you can easily score the slate tile, you can be sure it’s time for new slate on your roof. It’s a good idea to perform this test in multiple locations.

There, if you thought that might be difficult, you can be pleasantly surprised. If your roof passes these simple tests, you have peace of mind on the structural integrity of your slate roof. If it doesn’t pass, some of the other information on this site and blog will help you find a reputable and experienced slate roofer.

Slate Roofing Durability in Coastal Areas

The question often comes up about how well slate roofing holds up against the effects of coastal conditions like salt air, high winds, brutal winters, and other demands that nature throws at the roofs located in the coastal areas of Melbourne. The answer is divided into two seemingly paradoxical replies:

Slate roofing holds up exceptionally well against anything coastal conditions can throw at it, and, slate roofing can fail miserably when exposed to the ravages of salt air and other coastal conditions.

How can both be true?

Though they seem to contradict each other, the answer isn’t likely to surprise you when you have life experience. It all comes down to the quality of slate roofing materials used and skilled workmanship just like so many other things in life.

On the downside, salt air in coastal areas is a major catalyst for promoting rust. Nails used to secure slate roofing tiles to your roof can serve as a source for rust. Rust inevitably degrades the slate roofing and leads to delamination, cracking and/or breaking, leakage, and even dislodging of the slate tiles. High winds typical in coastal areas can turn slate roofing tiles into dangerous projectiles causing additional property damage or even personal injury.

How quickly can this failure occur?

As little as 3-4 years!

Yes, that sounds scary, and it should. But the good news is, there’s no better solution for roofing that endures the ravages of nature in coastal areas than slate roofing. Properly installed slate roofing tiles that are lab tested to assure strict quality standards for water and salt air resistance will protect your home or building for decades—typically 15 decades or longer!

Having a “master slater” doing your roof is vitally important. Due to the short life and premature failure, even potential danger of cheap slate roofing, it is no bargain. For a modest price difference, a proven professional will provide a roof that withstands the coastal conditions of Melbourne not just for your life, but your children’s and even grand children’s and great grand children’s.

Rust Stains On Slate Roofs

Poor quality slate roofing with faulty installation rusting after only 4 years!We’ve all seen rust stains on slate roofs here in Melbourne. What’s worse is that it happens surprisingly quickly even on new slate roofs.

What can you do about it?

Unfortunately, nothing. The problem is unrepairable. The only solution is to replace slate tiles that have rust stains.

There is one good thing to say about rust stains. They at least alert you to a problem because those stains will eventually become leaks so you know the roof needs attention. Not all slate roofing problems are so easy to see.

When you need a new slate roof or new slate tiles on an existing roof, there is only one effective strategy to avoiding rust stains…prevention. Rust stains are caused by faulty slate roofing installation. It is imperative that your slate roofer be experienced and use quality slate tiles. You’ll want to screen your slate roofing contractor very carefully.