Can you use polished concrete outside?
We often get asked at Policrete: “Can you install polished concrete outside?”. While concrete is an extremely durable and versatile material, the downside to a high polish is that it can make the concrete surface slippery when wet, meaning it’s not ideal for use in outdoor areas that might be exposed to wet weather.
Fortunately, there are other options available. Honed concrete and grind and seal concrete finishes are two of them. These finishes make concrete suitable for outdoor use, meaning you can achieve the concrete look in outdoor entertaining areas, swimming pools, external walkways, commercial foyers and outdoor public spaces.
What is honed concrete?
When installing concrete surfaces, the concrete is first ground down to expose the desired level of aggregate (the sand and stone that sits underneath the surface). This varies from nil exposure, where none of the stone is visible, to full exposure, where all of the stones are visible on the surface.
After grinding, concrete floors are then ‘honed’ using different levels of diamond grit to achieve the desired level of shine. The finer the diamond grit used, the higher the degree of shine.
While highly polished concrete looks great, the downside is that it can be slippery when wet. This means that while you’re free to choose the desired level of aggregate exposure for you outdoor surfaces, honed concrete for outdoor use can’t be highly polished and is only available in a matte finish.
Honed concrete is then sealed with a penetrating sealer to protect the concrete and help prevent staining. Because the sealer is absorbed into the concrete and doesn’t sit on the surface, it can’t be damaged, worn away or scratched by heavy foot traffic, making it a lower-maintenance and longer-lasting option than the grind and seal method explained below.
What is grind and seal concrete?
Another option for outdoor areas is the grind and seal method. Unlike honed concrete, grind and seal is available in matte, semi-gloss and high-gloss finishes, meaning it’s easier to achieve the polished concrete look.
The difference between polished concrete and grind and seal is that instead of mechanically polishing the surface with resins and polishing machines, the appearance of polished concrete is achieved by applying a topical sealer in your choice of matte or gloss. If using outside, a non-slip grit is added to this coating to ensure the surface is slip-resistant.
One of the advantages of grind and seal is that you can carry the polished concrete look from internal to external areas. In fact, grind and seal can be used in both indoor and outdoor areas.
On the downside, while still more durable than other outdoor flooring options like tiles, grind and seal concrete requires more maintenance than honed concrete. Unlike the penetrating sealer used on honed concrete, which is absorbed into the surface, the sealer used on grind and seal concrete sits on top of the surface, meaning it can be worn away, scratched and scuffed. Because of this, grind and seal floors may need to be resealed after a few years.
Installation of grind and seal concrete in outdoor spaces can be complex. For example, if moisture is trapped between the slab and the coating, it can cause discolouration of the surface. That’s why it’s important to consult an expert polished concrete specialist at the planning stage of your project. A professional concrete installer will be able to advise you on whether grind and seal is suitable for your outdoor area.
Using the right concrete for your outdoor space
At Policrete, we source all of our concrete from Hanson, a supplier of premium decorative and landscape concrete. Hanson supplies a number of different concretes suitable for outdoor use.
The Hanson Imagecrete Exposed concrete is a hard-wearing and low-maintenance surface that has a natural look and is slip-resistant, making it perfect for use in outdoor spaces that needs to withstand a lot of foot-traffic, such as commercial foyers, footpaths and outdoor public spaces.
Hanson’s Imagecrete Colour concrete is also great for outdoor use and is available in 62 different colours. The colour is achieved by dispersing a liquid oxide colour mix into the concrete. Because these oxides don’t break down and are UV-resistant, the colour won’t fade and will remain bright and vibrant, even if the surface is exposed to full sunlight day after day.
Using concrete around a swimming pool
Concrete around pools should never be highly polished. Instead, we recommend an acid wash and seal finish. The surface treatment makes the concrete surface more slip-resistant and more suitable for use around pools.
Acid wash is used to clean and prepare the concrete before you apply a sealer (if the concrete is dirty, the sealer may not adhere to the surface properly and could start to peel away after a few months).
If considering an acid wash and sealer for use around your pool, it’s best to hire a professional concrete installer. Working with acids can be hazardous, and working with a specialist will ensure the job is done safely and properly, resulting in a high-quality, long-lasting surface around your swimming pool.
How to get a safe, long-lasting and great-looking concrete floor for your outdoor space
If you’re looking for a hard-wearing, safe and stylish floor for your outdoor space, honed or grind and seal concrete are two great options. As always, it’s important to consult with an expert concrete installer to determine which option is most suitable for your project. Careful planning and quality installation will ensure your outdoor surfaces look great for years to come. Get in touch with the Policrete team to learn about using concrete to create a stunning outdoor space.
Are you an architect or builder considering polished concrete floors for your next build? Get in touch to speak to one of our specialists.