Natural stone is one of the world’s oldest building materials, and its attractiveness, strength and durability have ensured it is still as popular today. But whether York stone, Bath stone or any other type of natural stone, it can become damaged by ageing, extreme weather, and pollution. When done correctly, cleaning natural stone will help to preserve the building’s beauty and ensure it will continue to serve you for many years. However, while stone might be durable, incorrect cleaning methods can cause considerable damage either immediately during the cleaning process or some time afterwards. 

A historic dark stone building being steam cleaned by a person in high vis on a MEWP

Before you go ahead with cleaning natural stonework, make sure you know the type of stone it is, what kind of staining you are dealing with and the most effective and safest cleaning method for the stone.

Why clean natural stone?

Cleaning the stonework of a building improves its appearance, removes any impervious paintwork, and can help to blend the original stonework with new work carried out such as repairs or an extension. It is also essential for the overall structure of the building. Vehicle exhausts release nitrogen dioxide and sulphur dioxide into the air which reacts with the stone to form calcium sulphate. If not washed away by rainwater, these crystals will trap the polluted air particles producing a black crust, causing the stonework to deteriorate, triggering blisters and spalling of the surface. The effect of limestone decay is particularly severe along heavily trafficked roads. 

Cleaning natural stone helps to slow down the damage caused by deposits on masonry and will reveal the overall condition of the stonework where the deposits have concealed cracks, failed pointing, damaged stonework, or serious structural faults.  

Pre-cleaning survey

Before any stone cleaning begins, a survey of the building should be carried out to provide crucial background information on its style and construction. This survey should also take into account any conservation objectives. For instance, if the building has certain marks that reflect its age, this may need preserving. A pre-cleaning survey will identify the type, pattern and cause of the soiling and examine the building’s structure to see whether the soiling has caused damage or decay. These issues will all need reviewing within the context of the building itself, its history, location, construction and proximity to other buildings. The findings in the survey may decide the method of cleaning the building’s stonework is required, where and how. 

Natural stone cleaning methods

There are several different natural stone cleaning methods. However, the type of soiling, the pre-cleaning survey and pre-project cleaning test trial will determine the most appropriate form of cleaning. Some of the techniques commonly used include:

Some cleaning methods such as dry air abrasion, high pressure or continuous water spray can damage delicate stonework such as soft Bath stone if not carried out correctly by a professional. See our blog post Choosing the best cleaning solution for your stone building for more information.

Benefits of steam cleaning

Person in high vis in front of a brick and terracotta wall carrying out steam cleaning with hot steam flowing away.

Hot water cleaning, low-pressure cleaning, and steam cleaning are one of the safest methods of restoring and maintaining soiled building façades and exteriors made from natural stone such as sandstone, limestone, slate, or quartzite, and other natural stones. This process effectively removes staining such as traffic film, carbon, leeched salts, effluence staining, organic matter, environmental pollution and paint from the natural stonework. When just the right amount of pressure is applied, steam cleaning will remove dirt, and debris and restore a building’s natural stonework to its former glory without the use of harsh chemicals. 

Choosing the correct method for cleaning natural stone will help to preserve this precious piece of history and ensure the building continues to look its best for years to come.

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Building Transformation’s unquestionable honesty and enthusiasm for ensuring the client receives the correct whole-life solution (rather than a quick fix) resulted in us being able to ensure the building was not only returned to its former glory, but will stay that way for years to come. I would recommend them to anyone.

Kenny Gash - Carillion Amey

The work provided by Building Transformation was excellent. Their product and building exteriors knowledge is detailed, comprehensive and practically applied to the client’s needs. They offer a professional, detailed, high-quality and customer- focused service which meets the short, medium and long-term needs of the client, and provides practical, cost-realistic advice.

Kerry Quinn - Echo Arena

Customer service is paramount to Building Transformation and they invested vast amounts of time in providing me with a programme to facilitate what was a very complex and time-specific programme of work for the site. The quality and level of support provided by Building Transformation is priceless to any client/contractor.

Marc Blow MCIOB MBIFM - Carillion Amey

The approach and advice on setting up the works at the Wolverhampton Civic Centre were first-class. Building Transformation’s attention to detail was excellent and the RAMS were followed meticulously to every detail. We were delighted with the works and service, and would not hesitate to use them again, nor hesitate to recommend them to any organisation.

Kevin Egginton - Wolverhampton Council

A 200,000 sq. ft., four-storey leisure venue in the heart of Nottingham city centre surrounded by major traffic routes needed work to be done overnight to deal with the traffic issues, while the site remained open throughout. The project took around three weeks to complete and went exceptionally well; the Building Transformation staff were flexible and able to work round dynamic operational issues. The clean was of a high standard and has made a significant different to the image of the building. A very difficult job done well.

Suzanne Green - Land Securities

May & Co have worked with Building Transformation on a number of projects which have included external building cleaning and refurbishment. They provided a great service, supported by the high level of documentation from the initial quotation to books and industry-related guidance, all relevant to our project.

Anton Theobald - May & Co

I am very satisfied in the manner the job was conducted. Also the level of cleaning provided and attention to detail is much appreciated.

Waqas Bin Tahir - Ibis Southampton

I am using Building Transformation’s work to help justify façade restoration works around our business. They have produced excellent presentations on what can be achieved and is a brilliant piece of informed marketing that is helping slowly win people over in our business to take façade cleaning and restoration more seriously.

Needless to say Building Transformation is a name that is now becoming known and respected.

Simon Attwood - Broadgate Estates Ltd.

Building Transformation gave great communication throughout our projects.
It will be my pleasure to recommend Building Transformation.

Sarah Cameron - My Hotels Group

Just signed off the job with Richard. Myself, the bosses and the tenant all are very pleased with the work. It definitely looks rejuvenated just a case of painting the concrete window surrounds in the new year to finish it off. Have found your company and staff very professional and helpful which has facilitated a project with minimal inconvenience and disruption to our in situ tenants.

Mark Hollinshead - Headruddy Property Development

I had a walk around today with Dave and am impressed with the work so far. Dave and the team have done a great job.

I’d certainly love to work with you in the future so perhaps before the job is completed we could look at what opportunities there are for the future.

Marie Green - Novotel Sheffield

At this stage, from my point of view your team has been extremely professional, informing us of what was happening at all times and most importantly no disruption whatsoever to our guests and business.

Ludovic Verzi - Novotel Leeds

We are very satisfied in the manner the job was conducted. The operatives on site were very professional and communicated to us at all times.

Maria Pinana Mateu - Science Museum

The team at Building Transformation understood our challenge of finding a facade cleaning solution that would initially restore the glazing to its original state, protecting our building for years to come. Through intelligent and thorough testing right through to the full restoration of Block D, we have been very satisfied with the project management and delivery of the cleaning programme.

Colin Pilkington - Renaker Build Limited

Thank you for all the work that you carried out in cleaning the outside of our school. We are delighted with the results. You have managed to completely remove heavy staining from many areas around the building.

We found you extremely easy to work with: your quote was reasonable, you carried out the work quickly and you were very flexible in terms of timings.

Tamsin Griffith - Courtney Road Primary School, Bristol

have worked with Building Transformation on several projects within the hospitality industry and have found
them to provide high levels of professionalism and workmanship.


e will definitely be working with you again! Your engineers were very polite and accommodating every time they visited site and have done a first class job. I will be recommending Building Transformation to everyone!

Mark Healy - One Facility


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