Our photographs above show lichens growing on an asphalt roof shingle in situ above left.
Why does lichen grow on roof tiles.
Both of the organisms and plants like wet conditions therefore they tend to grow better on north facing roof slopes.
Traditionally lichen have been used to make dyes and this may be one reason that lichen can actually remove the dye from concrete tiles.
In the picture to the right you can see patches on the tile that are no longer red this is from lichen that has removed the concrete dye from those areas.
Moss lichen and mould can build up on your roof and degrade your tiles and also restrict the water flow off your roof.
If tiles become too brittle they can break even from basic cleaning activities.
Because lichens growing on a roof surface does not have as much thickness of body as moss it will hold less water on the roof surface and is less of a wear factor than moss.
The main reason moss is able to grow on roofs is that the surface of roof tiles filter out dirt from rainwater over time.
This can be aggravated by dead leaves blowing onto the roof becoming lodged and then decaying.
When this surface moisture freezes in cold temperatures it can lead to frost damage to roof shingles and other exterior surfaces.
Moss and lichen will grow on slates and clay tiles but their preference is concrete tiles or fibre cement slates sheets.
The older the tiles are the more brittle or fretted they become.
That is one of the reasons that you see a lot of moss and lichen on houses near the sea.
Another reason to remove lichen growth is your homeowner s insurance rates may increase.
Lichen holds moisture against the surface thus speeding up the wear and tear.
Mould when mould is growing on top of your roof it is often indicative of problems that started within the home.
Lichen holds moisture in place against surfaces which speeds up normal wear and tear.
Spores and seeds of mosses weeds and lichens can then be blown on top of these elements and sooner or later they begin to grow.
A quality anti fungal coating solution should be applied before any cleaning process is undertaking.
Lichen on terracotta roof tiles is particularly unappealing to the eye and is best handled before it has a chance to cake in and ruin the tiles.
So over time your roof shingles may bend and warp.
Steeper pitched roofs are less likely to support moss and lichen growth as they shed water more quickly than roofs with a low pitch.
Your insurance company may send out an inspector to drive by your home to observe any changes.
The lichen can also penetrate your roof s exterior causing the shingles to separate and spell disaster for your roof.
Moss and lichen tends to flourish on roofs in rural areas where trees are nearby and where there are shady damp conditions.
Roofs are especially susceptible to the growth and can be significantly damaged by lichen.
