Asbestos in Swimming Pools
Can a pool have Asbestos?
Yes, a pool can contain asbestos. Marblesheen is the most widely known swimming pool product to contain asbestos. However many swimming pools have asbestos products such as cement sheeting from the 60’s & 70’s that was used to hold the top of the skimmer box into place, in most cases the sheeting was tiled over making it hard to notice until the removal / demolition is done.
What is Marblesheen?
Marblesheen is a pool interior coating that is rendered over the pool concrete, marble-sheen consists of crushed white marble and white cement or offwhite cement.
Marblesheen in many cases is also known in the pool industry to contain asbestos, many pool owners are unaware.
It is not common for Marblesheen to get installed in swimming pools anymore & it has a reputation for deteriorating, becoming unstable, and crumbling away from the pool surface. While Marble-sheen surfaces did last a very long time, it wasn’t without issues.
Where is Marblesheen found in pools?
Marble-Sheen is rendered over the top of the concrete pool shell. Asbestos can also be found in other places in or around a pool. Sometimes when installing pebblecrete coping, an asbestos cement sheet was used over the swimming pool skimmer box as support for the installation of the pebble, the cement sheet would stay embedded under it, usually the pool tiler would tile over it making it difficult to spot and unintentionally making it a secret danger.
How was Marblesheen installed & where is it located?
Marblesheen was usually mixed in a cement mixer by the pool, the installers would open the bags of asbestos fibres and shake the bag into the marblesheen mix, which consists of white crushed marble and cement, once mixed they would carry the marblesheen into the pool with buckets and trowel it onto the surface.
Asbestos in Marblesheen
Prior to 1984 asbestos mixed within the marblesheen was very common practice, however asbestos has been found in Marblesheen pools built up to around the mid 90’s, so any marblesheen pool should be tested for asbestos.
The most common type of asbestos found in Marblesheen is chrysotile also known as white asbestos , while it is the most common in Marblesheen it is not the only type of fibre that can be detected, in some instances organic fibres including horse hair can be found in cementitious products or worse blue asbestos.
For more information regarding asbestos, you can learn more here Asbestos Information
What does Marblesheen look like?
Identifying Marblesheen
Marblesheen can be tricky to identify.
It can take many forms and develop many colour patterns over the years. The first step is your pool colour, a white/grey Marblesheen when filled with water typically makes your pool look like a light sky-blue colour, though this alone means nothing unless the pool is emptied.
- Greenish stains, from chemical burns or metals in the water can sometimes disguise Marblesheen.
- Deteriorated spots is usually a good indicator only if a pool surface has never been renovated. (Though this can also occur in Quartzon)
- Little spiders web cracks or larger cracks throughout the pool surface.
- Marblesheen started as white, and can still be white or greyish, greenish white/grey, stained and offwhite / yellow-ish, Unless painted.
How likely is a pool to have asbestos?
It is recommended to have an expert look at the swimming pool to make this determination. If the swimming pool was built in the mid 1990’s or earlier, it should be treated as highly likely to contain asbestos and you should get in touch with a swimming pool professional.
Marblesheen zoomed in has small crushed pieces of white/greyish Marble.
How to recognise Marblesheen
Here are some photos to help find / detect or recognize Marblesheen in a swimming pool, it is important to know that Marble-sheen can have these features individually as well as a combination of some or all of them!
Grey Marblesheen
Marblesheen was intended to be white since the main ingredient in the Marble mixture is white cement, many factors can come in to change the look of Marblesheen, time is the biggest culperate for any changes in the look and feel of the Marblesheen. Pool Chemicals can also affect the colour of the Marblesheen.
Calcium spots in MarbleSheen
Most Marblesheen will have calcium spots throughout the surface, in many cases it indicates hollow spots within the pool surface and can develope into what we call pot holes, this is when the marblesheen deteriorates so badly it goes right through to the concrete shell of the pool. This can be hard to see as calcium and Marblesheen can be similar in colour.
Cracks in Marblesheen
Marblesheen has a reputation for becoming unstable and loose, it can crumble and crack, in many instances the fine web cracks may not appear unless the pool is empty, and the cracks may be more visible if there is still some moisture within the marblesheen surface.
Off-white Marblesheen
Off-white Marblesheen is quite normal to come across, marblesheen can vary between White & Grey, to an off-white with a hint of green or yellow tone. Just like this picture shows you, Marblesheen can be prone to having calcium spots throughout the surface.
Green Stains in Marblesheen
Not to be confused with the previous Marble-Sheen, green stains such as these in the photo are typically inconsistent through the pool surface. Typically these stains are from metals in the pool water such as copper and they can oxidize on the swimming pool surface causing a greenish stain. Green or Blue stains can also be from burning the pool render with chemicals and is an important reminder as to why granule Salt or Chlorine should be diluted prior to be released into a swimming pool. Granule pool chemicals should be left to dissolve in a bucket prior to being added to the swimming pool water the so that the sediment does not sit on the pool surface. This is what the stains look like on a Marble-sheen surface.
Painted Marblesheen
This is considered the most dangerous of all Marblesheen. Painted Marblesheen means the asbestos is contained making it safer, usually until the paint has faded or a pool renovation is set to commence. Many people including professionals may not realize there is marblesheen behind the pool paint, which makes it a danger, when a pool has been painted it is advised to treat it carefully until it has been determined safe. In most cases a swimming pool renovation may require sandblasting, which should not and would not be done unless testing for asbestos was done & a certificate can be provided. Chemical peeling is the best option to remove swimming pool paint when asbestos fibres have been detected.
Swimming Pool Expert
For expert advice regarding asbestos in swimming pools.
Melbourne, VIC
You can also get in touch via email: andrew@localpoolrenovations.com.au
Images of your swimming pool are recommended to be attached to your emails, you can also include asbestos reports.