Humming and hawing over whether to clean the exterior of your building? For many businesses, it is perceived as a costly exercise that can be put on the long finger while budgets get gobbled up on interiors. However, cleaning your facade should be seen as a preventative measure and used as a diagnostic tool to assess the condition of your substrate. Failed pointing, water ingress or organic growth can cause costly structural damage if left untreated.
Of course, one of the most obvious reasons to clean your facade is aesthetics. Let’s face it, a building looks its best when it is free from grime, pollutants and unsightly growth. A build-up of grime and pollutants can obscure the architectural detail of a treasured building. However, cleaning is also necessary for the conservation of your facade and is an essential process for defending your building against the elements. Pollutants such as exhaust fumes can react with water and become acidic which causes damage to masonry. Paints and coatings on a building inhibit its ability to breathe, therefore trapping water in the substrate which can also damage your masonry.
The delicate matter of building restoration
As previously mentioned, it is also necessary to clean your facade for diagnostic purposes. It is essential to have a clean substrate in order to analyse the extent of damage and assess restoration work to be carried out. However, as with a lot of things in life, quite often the fastest and cheapest route is by far the most expensive in the long term. Before undertaking any cleaning and restoration works it is very important to positively identify all the substrates on the building. Each type of substrate may require a different approach to the task.
Test samples should always be carried out on each substrate to establish the most appropriate method and set out client expectations. Not all mistakes can be fixed. Water is the single most damaging element to masonry and attempting to clean your facade by saturating it with water will cause major damage and further deterioration of your masonry. Saturating your stone or brick façade will activate inherent soluble salts, resulting in efflorescence. This is a white powdery residue that you often see on brick facades. Stone facades can develop brown staining on drying out if contaminated with ferrites i.e. iron found in water. This is very difficult to rectify and can only be removed by using harsh chemicals over numerous applications.
A statue cleaned using DOFF steam cleaning – before and after
High-pressure washing is not the solution
High-pressure washing is not advised, as it drives water too deep into your substrate, leading to possible surface damage. This kind of washing will remove the natural patina of bricks which act as a waterproof membrane. It can cause pitting in your bricks, leaving them completely exposed to our wet climate. High-pressure washing also facilitates the penetration of water through defective joints and will dislodge pointing. Once water is trapped in your substrate, it will cause cracking and spalling as it expands with thaw/freeze cycles. Pressure washing can break delicately carved detail on stone facades, and don’t even get us started on the damage pressure washing will cause to modern-day thin renders such as monocouche!
Pavement steam cleaning
P Mac’s foolproof exterior cleaning methods
Water is required to clean a building, but we advise using it very sparingly with low pressure and at a very high temperature. A trained expert will know what pressure can be applied to different substrates and an experienced operator will also not saturate the surface so it can dry quickly. At P Mac, we abide by minimum intervention and will always use the least destructive method when it comes to cleaning and restoring surfaces.
Facade cleaning using DOFF steam cleaning and a chemical clean
DOFF steam cleaning
When it comes to cleaning stone, brick, concrete or render, our first line of cleaning is usually a low-pressure steam clean using the DOFF system. DOFF uses steam and superheated water to 150°C in a unique way tailored to the type of material that needs to be removed. The DOFF system is ideal for removing superficial soiling. The various sizes of lance and nozzles on the machine make it perfect for reaching recesses in carved surfaces. It is able to remove many paint coatings, light greasy soiling and chewing gum. It will also remove algae, bird droppings and can kill off spores, avoiding the need for chemical biocides.
Cleaning the granite walls of Liffey Quay
TORC cleaning system
Our next line of cleaning is the TORC system. The TORC system is a gentle, safe and effective cleaning system for use on historic buildings and their particularly delicate and friable surfaces. The TORC system creates a soft swirling vortex using a mixture of low air pressure, low water volume and fine granules to ensure its effectiveness. This cleaning method is used for more targeted cleaning and it is ideal for removing carbon, heavy staining, limescale and graffiti. It will also remove some paint types from materials such as stone, brick, metals, wood and plaster.
We know what type of cleaning system is best for your building
In a lot of cases, we employ a combination of cleaning methods best suited to each individual project to achieve the best possible result. Chemicals are often introduced to tackle paints, graffiti and specific staining, such as rust and oil stains. Chemical cleaners work on the principle of dissolving dirt by combining chemical reactions. We use different chemicals and chemical strengths depending on the type of contaminate. Alkaline cleaners are used for the effective removal of heavy carbon deposits and organic soiling. This type of cleaner is suitable for most stone surfaces – except for polished marble. Acidic chemicals are ideal for removing decades of soiling and can be used only on acidic resistant masonries.
Chemical cleaning is a science. Knowledge and experience are crucial to achieving the desired result in a safe manner. The incorrect use of chemicals can cause irreversible damage to your substrate. It is also paramount to ensure only trained operatives are working with chemicals as they will adhere to all health and safety regulations, ensuring protection for themselves, the public as well as all areas not to be treated.
If you would like to know more about our expert cleaning and restoration services, please get in contact today.