Limestone Learning Center

Cleaning Exterior Limestone Walls

Restoring Beautiful Limestone

Limestone is a great choice for exterior walls. Not only is it durable, but limestone comes in a huge variety of visually pleasing colors, ranging from standards tans to grey, blue, pink, green, and more. Our team at Impression adores creating custom home pieces to last a lifetime, but what happens when your limestone needs upkeep? In our years of expertise, we’ve learned a lot, including how to keep exterior limestone walls looking beautiful forever. Read on for the steps to cleaning your exterior limestone walls, keeping in mind that more severe signs of degradation may require professional cleaning.

Recognizing Damage

The first question you may be asking is, “How do I know if my exterior limestone wall needs cleaning?” When you look at your exterior walls every day, you may not notice gradual changes. Key characteristics to look for are mold and dark streaks from dirt and moisture. Overall, the limestone will look more “cloudy” and splotchy.

Marking the Area

To ensure that cleaning agents don’t affect any other materials your building is made of, tape off the area you will clean (or want to be cleaned by a company). This prevents a mixture of cleaner and dirt from spraying onto surrounding walls. If possible, aim for an eco-friendly spray that won’t harm surrounding plants and animals when it comes into contact with the ground.


The next step is to actually get to cleaning! A pump sprayer should be filled with a mild cleaner specific to limestone in order to properly remove any dirt and debris without etching or damaging the limestone. Even if harsh agents don’t leave obvious marks, using the wrong cleaner can affect the porosity, leaving the limestone open to further damage and a shorter lifespan. After being applied, the product will continue to fight deeper-than-surface-level mold for up to two weeks. In order to push the cleaner into deeper pores of the limestone, natural fiber brushes should be used to rub it in. Then, rinse the exterior at a low-pressure. Approximately 1600 psi is enough to wash off the surface-level product.

Take Some Time

After rinsing, it’s time to let the limestone dry. There’s no way to manually and effectively dry it; it must be left alone for a few days to dry on its own. Make note that some sections of the wall may receive more direct sunlight, and will dry faster. The exterior limestone wall must be left to dry until all portions are entirely dry.


The last step is to reseal your limestone. You’ve just cleaned out all of the mold and dirt – now keep out future damage! A limestone sealer can protect the surface level from absorbing water, preventing the growth of mold. Because of limestone’s porosity, it’s best to use two coats, but allow the first coat to fully dry before applying a second one. For hard-to-reach areas and crevices, rolling on the sealant can be more effective.

Impression Does Limestone Right

When properly cleaned and resealed from time to time, your exterior limestone walls can last for years. For additional tips or professional cleaning, contact Impression for advice and referrals! And if you don’t yet have limestone exterior walls, contact Impression today! Our team specializes in artisanal, custom home features, and we’re ready to make your home stand out with limestone.

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