About Your Roof: 

Cleaning Monier Roofs

Moss, Algae, and Lichen erode the cement based colour coating and mortar joints on your concrete tile roof.  Regular roof cleaning will extend the service life and improves the appearance of Monier tiles and your home.

How to Clean & Maintain Monier Tiles

New Monier concrete tiles  will resist moss, algae and lichen growths for up to 4 years.
Moss, algae and lichens will then begin to naturally grow once the factory colour begins the weather and erode.  Lichens and moss easily grow on the  flexible pointing mortar that secures the ridge tiles, and will be noticeable before any growth appears on the roof tiles.

These growths not only look unsightly – they will damage to the high quality factory colour coating, shortening your roofs  service life and eroding the mortar joints.

Bio-Shield cleans algae, moss and lichens and maintains your Monier roof without harsh pressure cleaning, aggressive cleaning chemicals or washing down, – its a simple, quick and no mess application and reccommended by Monier Roofing


The Bio-Shield Cleaning Process

Bio-Shield gives excellent cleaning results on concrete tile roofs, with a faster clean up than comparable cleaning products.
We apply Bio-Shield to your roof to kill all the moss, algae and lichens within  1 to 2 hours.
After 2 to 4  weeks the cleaning process will be visible, as rainfall and wind begin to remove the dead growths, revealing more and more of your roofs original colour.
After 6 to 12 months, the roof will be fully clean and stay clean for up to 2 years.


Maintain your roof with Bio-Shield

We recommend re- application of Bio-Shield every 2 to 3 years, to keep the roof clean and protected.
With regular applications of Bio-Shield, algae or lichen spores and light re-growths will be quickly removed, and the roof will stay clean for another 2 to 3 years.

Lighter colours will show up even low levels of re-growths so should be treated with Bio-Shield every 2 years

WARNING – Water Blast / Pressure Cleaning:
Concrete tile roofs should only be water blast cleaned as preparation for repainting, never to remove lichen and algae growths, it will damage the cement based colour coating and mortar joints, and allow water to enter the roof space.
For repainting water blast cleaning is essential.
Best practice is to apply Bio-Shield then wash the roof down carefully after 2 to 3 weeks as the perfect  preparation for recoating.


2 Year Guarantee

Bio-Shield applications are covered by a written 2 Year Guarantee

Expert Monier Tile Cleaning

Roof Cleaning Ltd are genuine specialists in Bio-Shield roof cleaning, with over 40 years experience and more than 10,000 + roofs cleaned and treated with Bio-Shield®. Expert Application, Proven Performance, Reliable Results

Is Bio-Shield safe to use on my roof?

Yes, Bio-Shield has been used commercially and safely for over 36 years and on more than 9300 roofs in New Zealand. It is not acidic, not a bleach and not abrasive like pressure washing, so won’t cause any damage to the cement color coating, pointing mortar, skylights, vents, solar panels or other fittings and fixtures commonly found on roofs.

How long will my roof take to clean up after being treated with Bio-Shield?

 A general guideline for the clean up time after initial Bio-Shield application would be 3 months and up to 6 months, if the growths are heavy and well established on the roof. Modern concrete tiles in good condition will clean up fastest – in as little as 3 months while older concrete tile roofs with heavy black algae and moss will take up to 12 months. 
Other factors that affect clean up times is the pitch of the roof and how much rain falls on the roof once the dead growths have begun to break down.
 Roofs that have previously been cleaned with Bio-Shield and is having a 2 or 3 yearly maintenance treatment can clean up in a matter of weeks if the growths are light.

Can I still collect rain water from my roof once its been treated with Bio-Shield?

Yes, Bio-Shield is water based, water soluble and bio-degradable so it is safe to use on roofs that collect drinking water. The storage tank will be disconnected before application and can be reconnected after a minimum of 3 to 4 weeks and at least one day of rain has flushed the roof clear of Bio-Shield residue.

A diverter can be installed on the tank inlet pipe, on above ground tanks to isolate the water tank form the roof and make reconnection and any future disconnections a 15 second task. No need to remove down pipes or fit expensive and ineffective diverters to the down pipes

We do not recommended cleaning a roof over the summer months, from January to March , in drier areas as there may not be enough rain to flush the roof and refill the tank after it is reconnected.

How often should my roof be treated with Bio-Shield?

Concrete tile roofs should be treated every 2 years to maintain them in a clean condition. Regular treatments will help to preserve the factory colour coating in good condition.

The micro climate around a roof will have a large influence on timing between the maintenance treatments.

If there are trees near the roof, the roof is steep pitched or birds habitually use the roof to rest or nest, annual or 2 yearly treatments may be required to keep the roof clean.

My roof was treated by another company and it did not clean up. What happened?

Unfortunately some applications by companies that are not specialists in roof cleaning, for example house wash, gutter cleaners or handymen, are not being done correctly and leaving a patchy clean up from incorrect or incomplete application.
Bio-Shield gives a faster and superior clean up on concrete roofs. When Bio-Shield is applied to your roof, we give a written guarantee  it will clean up and stay clean clean up.

Will Bio-Shield kill my plants?

Bio-Shield can not kill plants, it is a surface santizer, not a systemic garden spray.
It can safely be used on lawns to kill moss and on tree trunks and branches to kill lichen.
In sunny conditions, some delicate leaved plants can get spotting on leaves from contact with Bio-Shield so any affected plants are hosed down after the application.

Edible plants near the roof are always hosed down after the application.
Bio-Shield is fully bio-degradable when in contact with organic matter and soil

Is Bio-Shield harmful to animals and pets?

The active ingredient in Bio-Shield has been safely and continuously used in the the food industry, in hospitals, veterinary clinics and zoos as a hard surface sanitiser for over 60 years.

The only precautions we take are to move feed bowls and toys away from the roof, and flush them out after the application is complete.

Is there a Guarantee?

When Bio-Shield is applied to any roof we provide a written 2 year Guarantee on the effectiveness of the application.

While there are conditions to this warranty, these are common across all roof treatments as they relate to the  situation, pitch and conditions around the roof, not the quality of the application.

You should be aware of the limitations that the above conditions – Read More