My Blog

Render cleaning

05/15/2014 22:09:00

Greening render :

Why and how to control it.

In the past 3 decades or so self finished renders became popular among architects. There are good reasons for this, both architectural and practical. For the designer, new finishes difficult to obtain with paint were offered. Smooth, textured, with mica sparkles or colour pebbles. They are low maintenance too. Every now and again cleaned, but never painted again. On site, no more curing time before finishing the building. It suits modern building constraints.

However, the cleaning periodicity has reduced from 5 years to 4 and sometime 3 years. The introduction of wall insulation appears to be the prime reason. Broadly, more heat transfer through the wall means a drier render and less microbial growth. The amount of insulation conditions the rapidity of the microbial growth. The position of the insulation within the wall is also instrumental in that if will affect the thermal inertia of

the outer leaf, and it’s behaviour to diurnal cycles.

Architecture is also responsible.

Flush, crisp line facades without shadow gaps at parapet and sills will inevitably lead to microbial disfiguration in a wet climate. Published studies show that a temperature increase of 1 to 2OK leads to decreasing the relative humidity of the render by approximately 10%. The white patches on soiled render correspond to a small variation in the heat transfer across the wall, sometimes revealing the position of the insulation fixings or a radiator. The white patches have stayed cleaner.

Formation & composition of a biofilm.

A biofilm forms when certain microorganisms adhere to a surface in a moist environment and begin to reproduce.

Biofilm formation on surfaces usually starts with phototrophic organisms (algae, cyanobacteria) which use carbon dioxide (CO2) from the atmosphere and sunlight as their carbon and energy source.

Heterotrophic organisms (most bacteria and all fungi) need some organic source for their growth, and this is provided by the metabolites of phototrophic organisms or by air- borne deposition. The biofilm community is therefore sometimes formed by a single microbial species, but in nature biofilms almost always consist of mixtures of many species of bacteria, as well as fungi, algae, yeasts, protozoa, and

other microorganisms, along with non-living debris and corrosion products.

Red algae

The genus would not, at first glance, be taken as a green alga. Free-living species are mostly yellow to bright orange or red-brown in colour, due to the orange pigment, haematochrome ( β‐carotene), which usually hides the green of the chlorophyll. The genus is terrestrial and is often found in

Europe on rocks, walls and tree bark. Where they are found on

buildings, they can cause severe mechanical degradation and

deterioration.

All biofilm forming microorganisms may cause biodeterioration

and degrade stone or render mechanically, chemically and aesthetically through the metabolic activities and biomineralization process in these biofilms. The porosity of the surface, it's mineral composition, alkalinity and it's ability to retain air borne sea salts creates an environment favourable to the settlement of microrganisms.

Trentepholia have been identified as one of the most common

species to be isolated from walls and buildings in Western Ireland

Cleaning a contaminated render.

The straight forward way of controlling the biofilm is by impregnating the

surface with a solution of quaternary ammonium. The product Algoclear

Pro works on the biofilm by puncturing microorganisms cell walls. It does not interact with the mineral components of self finished renders and does not contain any compound deleterious to the colouring agents or

the surface cohesion. In particular, the product has a neutral pH.

On porous render, the surfactant active will decontaminate deep into the surface porosity by capillary action.

The reaction to the treatment varies from specie to specie:

Algae - green and red - will die within minutes of the application. If the algal film is thick enough, a milky sheen will replace it for a short period, before dispersing in the wind. The orange pigment originating from the red algae Trentepholia may dwell in the surface porosity, but being water soluble will wash away with the rain. 10 days is a reasonable prediction.The treatment is by spray.

Bacteria and cyanobacteria have thin cell walls and die at rates varying

with the concentration of the Algoclear solution. At a normal rate all studied species die within one hour. The self cleansing process takes a few days in normal exposure. The treatment is by spray.

Moulds : They are a group of filamentous fungi. Their structure enable them to key their filaments in the porosity of render and even rock. As a result, moulds do not self cleanse as readily as algae.

The most common species of fungi on facades are the Cladosporium spp and Alternaria spp. Both metabolise a black pigment protecting them from UV radiations, and causing some staining of the

surface. Moulds are killed by a solution of Algoclear within approximately one hour. The self cleansing however can take several months, or is helped in a second visit by rinsing with fresh water.

The treatment of moulds is best carried out in 3 steps. First remove the thick with a scraper or brush and water until the substrate is clearly visible. Apply a 1/30 solution of Algoclear Pro using a soft bristle brush. This helps softening the biofilm. After brushing, a rapid rinsing with a solution 1/30 Algoclear Pro will complete the second step. About 6 weeks after the treatment the black discolourations should have significantly receded. It will normally wash away naturally but it has been observed in a minority of cases that some rinsing had to take place as a final step.

It must be noted that a key to durability of render cleaning lies in how

clean the water running over it is. If it transports more of the same

cocktail of species, the treatment will not be durable. Care must be taken in thoroughly decontaminating parapet copings, verge overcloak and ideally the roof above.

Rough cast and pebble dash.

Textured surfaces generally catch some grime as well as hosting life. The

best option is to brush a solution 1/30 Algoclear Pro into the surface using a soft brush. The hardness of the bristle is a matter of personal preference between soft and medium soft. Upon brushing an area, it is best to rinse the dirt lifted by the brush from the surface with a solution of Algoclear.

Breaking the Mould

03/27/2014 19:48:00

Breaking the Mould

Mould is easier to clean than the soot of old, but with the return of clean air, nature has reclaimed ground in a way not always foreseen. Problems sometimes arise when a building does not receive its full share of sun. In other places there are not enough sunny days in a year to stop deleterious growth. The issue does not affect all materials in the same way. Most roofing materials will someday need cleaning, but not all, and not at the same intervals. Choosing a roofing material with regard to its susceptibility to mould and moss encroachment is good design practice in shady locations. Below is a brief summary of material behaviours towards biological growth and reactivity to a non-aggressive biocide treatment.

Natural slates are not porous and display a smooth surface. As a result the material dries rapidly and is not naturally prone to roof growth with the notable exception of yellow lichen in coastal environments. The material cleanses readily upon treatment. It is a product of choice for shady locations.

Man-made slates offer some of the advantages of natural slates, but not always to the same degree.

Fired clay of good quality is not porous. The surface dries rapidly and sheds the bio film satisfactorily when treated. The roof surface is however more textured than slates offering intersects where growth can take a foothold.

Old clay tile roofs are fragile and are best treated from the eaves.

Concrete tiles are not indicated in the vicinity of tall trees. The high porosity combined with a rough surface provides a natural host surface. Removing mated moss from concrete tiles is labour intensive. The material cleanses well, but more slowly than other materials. The alkalinity of the surface seems to benefit black blanket moulds. In recent years smooth and less absorbent concrete tiles have arrived on the market. They are a better choice for higher humidity regions.

Metals:

Zinc is not a natural host to live contaminants. It is however susceptible to organic acid releases from rotting leaves, moss and lichen and should be avoided on lower draining slopes and box gutters.

Lead is also not a natural substrate for life. It is vulnerable to mild organic acids but paradoxically resistant to harsher mineral ones. Mossy tiled roofs draining into lead gutters will eventually jeopardise its integrity.

Copper has biocide properties. Water running over copper will acquire some of its cathodic properties by contact and hampering further downstream growth. The protection may not be sufficient to maintain the tiles in pristine condition along the whole rafter length. On canal tiles the protection is limited to the trough, where it is still the most needed.

Aluminium is not particularly affected by acid releases. Water running over it will become anodic and display the reverse effect to that observed on copper. The illustration of this is seen in the splash area of TV aerials.

Flat roof felts of bituminous kinds are not unduly prone to moss, but ponding, cluttered designs and raised walkways will host them. PVC felts become very slippery, but as is usual with algae, the treatment is rapid.

Organic materials are best used in full light where they can dry rapidly. Durable presence of mould and algae will eventually jeopardise their integrity as roof covering. As the lining of wood shingles washes away, the grey cellulose needles are exposed and offer a slightly abrasive surface hosting algae. The treatment will reinstate the silver grey appearance for some time. Thatch, if badly affected will need combing beforehand.

For the existing stock, periodical maintenance is the solution. The general wisdom is to opt for the milder cleaning processes before considering harsher ones. Blanket moss has to be removed by hand, bagged and disposed of in all cases. The tiles can then be treated by the appropriate biocide.

After the treatment, the dead bio-film will begin to loosen under diurnal and seasonal cycles, until the roof has regained the true original colour of its material. The rate of cleansing will vary greatly with the type of material, and the exposure to wind and driving rain. Not all chemicals are appropriate, and a few only authorised by the Health and Safety Executive (HSE). All formaldehydes, caustic soda or bleach based chemical are proscribed.

The application method and knowledge is as important as the biocide itself. Jet cleaning is seldom appropriate to roof cleaning. The pressure removes surface aggregates, creating a moisture retaining surface favourable to the return of the contaminants. Tile impregnation and coatings are ways of mitigating the damage done by jetting, but at a cost sometimes higher than simply replacing the tiles by new ones.

In conclusion, the return of clean air means new parameters for the choice of roofing materials by the Architectural Technology professional, and the specification of a non aggressive maintenance procedure for existing roofs. This is easily searched for on the Internet. A comprehensive approach to roof cleaning and the provision of specification support is a sign of an experienced specifier.

The author is Managing Director of TVSPLtd, which specialises in a roof cleaning process known as the Algoclear Pro Roof System, supplier to HD Roofing Services Ireland.

Keeping a roof clean.

03/10/2014 17:56:00

Keeping a roof clean

By F. Moal

When looking at an ageing building, few people cast a critical eye at the state of the roof. The windows are clean, the garden tidy and the interior spotless, but the roof is almost invariably unkempt. Black moulds hide it's colour and moss slowly mats itself in the bonds, so slowly that few take notice.

The encroachment of grime and moss has it's effects : Beyond the architectural downgrade the fabric of the building is at risk. Doing nothing is ultimately the expensive option. The risk varies with the nature of the roofing material : Thatch and wood shingles are at a more immediate risk of decay.

Metals erode under the acidic releases of lichen and moss. Lead and zinc used in soakers and rainwater disposal will thin down to eventually leak. Clay tiles need to dry between rainfalls to fulfill the promise of durability - if not premature shaling or frost damage may occur.

On all material the permanent presence of a bio film is deleterious by increasing capillary creep in laps and interstices. This in turn leads to undetectable moisture ingress. Generally materials retaining moistures are prone to contamination and combined with a shady winter exposure porous materials such as concrete tiles will become a good host for moulds such as A. Niger, then algae, followed by moss and lichen. As the bio film becomes established, the moistures are more permanent, and the cycle accelerates.

Architects do not seem to enter this constrain in their choice of roof material :

This was of no consequence in the days of acidic rain, but cleaner air results in nature reclaiming it's place in unforeseen ways. There is no easy answer to the return of nature :

Excessive moss has to be removed by hand. Mechanical means used on the ground are ill adapted to a pitch roof.

Jetting causes irremediable erosion to the surface. As a result the un-wanted host returns with a vengeance, only to hide the uneven, permanent discolorations of the roofing tiles. After clearing the roof from the bulky growth the next and final step is to spray the area with a dedicated anti algal wash. The right product, such as Mossgo-Pro will kill the remaining biological life at the surface and, most importantly, in laps and interstices. The dead bio film will soon loosen under diurnal cycles, helped by the wind, rain, heat and frost.

Self cleansing is a lengthy affair - months in most cases with latent effects stretching over a period of two or three years. The roof will become cleaner with the change of seasons and reveal it's original colour and texture.

There is no known preventative measure of any durability.

Clear hydrophobic resins degrade under UV in a matter of months. The same causes - substrate porosity and sun exposure - will have the same effects, at the same rate. This however is slow and a roof treatment is to be regarded as decennial maintenance.

Further maintenance will not be as heavy as the first clean, if carried out as or before the surface contamination triggers the condition for accelerated growth.

On the continent, antiseptic roof shampoo has been standard practice for decades. Roofing firms offer it as a standard way of finishing remedial work and as preparation to fitting out solar panels. In Britain the practice is expending quickly : The process has been adapted to the northern more demanding climate of the British Isles.

The website www.roofclean.co.uk hosts a wealth of information on roof maintenance treatment.

HD Cleaning Services in Ireland, are among the most experienced contractors to use the Algoclear pro soft wash cleaning system. For more info or advice call Andrew on 087 9323863 or mail him at hdsoftwash@gmail.com

Soft Wash wall cleaning

03/07/2014 18:18:00

Hi Folks,

Just a quick one today on something that we are coming across a quite a bit lately.

Wall Cleaning..

Walls, roughcast renders and pebble dash treatment.

The extensive use of rough cast renders and pebble dash on walls has led to the development of appropriate cleaning techniques.

Coloured renders or Monochouche as it’s also known was particularly popular during the most recent building boom here in Ireland.

Although the new build industry has all but gone these types of plastering finishes are appearing more and more as services such as External Insulation continue to grow.

There’s nothing wrong with these wall coverings, done right they actually look really well and versus a traditionally plastered then painted wall I’d choose a coloured render all day long.

Like all external surfaces though it’s only a matter of time before they become dull, discoloured and stained from growths such as red and green algae or lichen. Trouble is, due to the granular type finish to render or the easily loosened pebbles on pebble dashing the very last thing you would want near these surfaces is PRESSURE WASHERS!

I recently treated a roof for a girl whose house was finished in a bright yellow render, the place was immaculate, you could tell she spent many hours in the garden and cleaning her home. A little too much as it happened. I asked what happened to the gable wall where I noticed a section where there was streaks going in all sorts of directions. Putting her hand to her forehead she told me that after noticing a red colour appearing on the wall she decided to try and rinse it off with her little electric pressure washer, big mistake!

Like our Roof Cleaning technique, our treatment of Moss, Algae and Lichen is soft and safe enough to use on any type of external surface without any risk of damage to the substrate, and without the use of PRESSURE WASHERS!

Specialist cleaning for all types of exterior surfaces.

Very effective on roughcast render and pebble dashed surfaces. These types of surfaces are especially sensitive to all forms of aggressive cleaning.

Soft wash exterior cleaning

03/05/2014 20:01:00

Hi!

Welcome to my web page softwashcleaning.ie and to my first blog post.

I hope to add a post here regularly, and my main aim is to show and explain the service we provide and hopefully help people to make educated decisions when it comes to the exterior maintenance of there home, business premises or local authority surroundings.

First of all a little about us.

We began in 2011 our first business, HD Roofing Services, one of our principal services involved the cleaning of roof surfaces using a product know as Algoclear. Since the beginning, our roof cleaning service has gone from strength to strength, it has been a huge help in us sustaining what is basically a construction business in the middle of recession that has seen countless numbers of guys like us, have to up and leave in search of work.

With roof cleaning we found that more and more people were asking us if our products and methods were suitable for other surfaces, such as paths, drives, decking and so on..

This demand has lead us over the last couple of years to start familiarising ourselves with the pro's and con's of different types of exterior cleaning and what is the best practice for each surface you encounter, this led to us starting our sister business if you like, HD Cleaning Services.

What makes us different to every other exterior cleaning business?

Show me another that doesn't own a high pressure washer!

Our business is all about 'Soft Wash'.

No high pressure jetting and no harmful chemicals.

Effective cleaning methods that provide longer lasting results whilst prolonging the life expectancy of the surface material, be it concrete, stone, render, wood, plastic, metal and so forth..

So that's it for my first post, short and sweet.

Now i'm off to take the pressure out of cleaning!

Asbestos slate roof.

Moss and algae had completely covered the original colour of the slate.

These three pics show the progress of our soft wash cleaning method.

Top: Before

Middle: During treatment

Bottom: After. Roughly three months of weathering later, the slate had completely returned to its original appearance.

No paint gimmicks or high pressure washers were used.