Licenced Builder (and My Home Improvements’ Managing Director) Greg Catton explains why lichens form and why you should remove them with a tile roof restoration …fast!
If you lived out in the Simpson Desert, you probably wouldn’t have to worry about mould, moss and algae (also known as lichens) growing on your tiled roof.
Poisonous snakes, scorpions and dying of thirst maybe, but mould…I very much doubt it!
You see mould doesn’t grow in full sun. Or perhaps I should say it “rarely” grows in full sun.
Lichens and other algae are some of the hardiest growth organisms found in nature, and they can grow in the harshest conditions on the planet, so I wouldn’t put anything past them.
However, generally speaking they prefer dark, damp spaces, like the minute space between a cement roof tile and the roof paint that covers it.
If that concrete tile roof just happens to be facing south, in a leafy suburb, and spends much of the day under a shady tree, the roof lichen will positively thrive and that can be fraught with problems.
And I don’t just mean cosmetic problems – although the lichen will turn your roof an unsightly blackish green, and make it look old before its time.
The problem with moss and lichens on tile roofs.
You’ll notice that I didn’t say on metal roofs. That is because lichen don’t take to metal roofs because:
- there are no nutrients for them to feed on, and
- metal is less porous, so they would simply wash off in the first downpour.
The trouble with lichens on your roof is that get under the paint surface and start to leach the nutrients out of the binding cement and other minerals in the concrete. This can in time make the cement roof tile dryer and more brittle, thus potentially shortening the tile’s lifespan.
On top of that, as the lichens get bigger, the roof paint starts to lift and will eventually begin to crack, peel and lift off exposing the tile to the damaging elements.
– peeling roof paint can be a big problem.
Moss and lichens are also like mini-sponges – they retain a lot of water and their added weight (concrete roof tiles already weigh 5kg) can, over the course of several years, cause the supporting timber framework to bow and warp… leading to even further complications.
The wrong way to remove moss from roofs
In my experience, a lot of people turn a blind eye to roof moss removal and think: “If I don’t see it, I don’t need it”. The old ‘out of sight, out of mind’ approach. Or they hope it will just go away. Trust me, it won’t.
They also baulk at the relative high cost of quality roof fungicides, and consider taking their gurney up on the roof and hosing it off themselves.
There are three things very wrong with this.
- Stomping around on a wet, slippery roof carrying a relatively heavy high pressure sprayer with a cumbersome hose attached is an accident just waiting to happen. (NB. NEVER do this near the powerline! Broken legs are one thing, but electrocution is just not worth it.)
- This is only a short term fix. The same conditions that led to the lichens growing in the first place are still there, and will definitely grow back, and
- The high pressure spray WILL remove the moss and mould. However, the force of the spray may also crack the tiles and damage the pointing, causing unwanted damage. On top of that, the concentrated spray can remove the paint and the tiles’ protective coating. This defeats the purpose and allows even more lichens to get a REAL foothold in the exposed aggregate and flourish. If left, they will break down the concrete structure of your roof.
The bottom line is, you really can’t take short cuts. You definitely need a fungicide. Unless, of course, you use TileFlex Roof Paint (more about it in a minute).
The right way to remove lichens from roofs.
The right way – in fact the only way – to carry out black mould removal is with a roof fungicide (also known as a roof moss killer).
You could consider doing your own roof moss removal, or you could engage a professional roof cleaning service, such as the one offered by My Home Improvements, to take care of it for you.
We have the experience and the equipment to remove roof moss and mould safely, and that way you’ll know that the roof mould will be well and truly goooooone!
According to the CSIRO, lichens can be eradicated by a number of toxic washes.
A fungicide comprised of a 4% copper sulphate solution will do the job and, best of all, it will have residual effects that will prevent the lichen and mould from growing back for several years.
Of course the lichens won’t be dislodged the instant they are killed; instead they will be removed gradually by the weather over time.
If you’re impatient like me, our roof cleaning service team can speed up this process by waiting a week or so after the initial application – for the growth to completely dry out – and then brushing it off.
Of course, once the lichens are completely gone, this is an excellent time to consider re-painting your roof – after all, a lot of the prep work will have already been done.
And I say without favour, or fear of contradiction, that if you’re going to have your roof repainted, then you really must insist on TileFlex roof coatings.
The roof paint with a built-in fungicide.
Not only do TileFlex roof coatings stay cleaner and glossier for much longer than any conventional acrylic roof coating thanks to their inbuilt Nano Technology, but they come complete with anti-fungal additives that will keep your roof free from moss, lichen and bacteria.
Its highly effective polymer preservatives provide long lasting broad spectrum, algaecide and fungicide protection to prevent polymer discolouration and deterioration and moss and lichen growth for many years.
And unlike many other roof coatings, TileFlex is also user friendly because it does not contain environmentally harmful formaldehyde preservatives. That makes it suitable for the collection of drinking water.
Keeping lichens off your roof.
As I mentioned, lichens, moss, mould and other algae love damp, dark places, so you need to make sure your roof is exposed to as much sun as possible.
If you can, try trimming back the branches of overhanging trees to let the sunlight onto your roof and dry them out.
Plus, keep your gutters and valleys as free from leaves as possible to ensure that water drains away quickly so your roof will be dryer.
For more information and advice about roof fungicides – or to arrange an obligation-free Consult – please call 07 3808 0700 and speak to one of our friendly, helpful roof cleaning consultants, or simply click here to contact us.