How to Maintain Rammed Earth Structures

Rammed earth, an ancient building technique, has proven its ability to stand the test of time, but some maintenance is required to keep structures standing tall. Aussie Built uses Tech-Dry® Plasticure in all of our projects to ensure waterproofing for the lifetime of each build, but surface sealers are also effective when it comes to protecting earth structures.

Without the use of Plasticure, we recommend using both Tech-Dry’s Earth Binder and Stabilised Earth Water Repellent W. Surface sealers require regular maintenance every 3-5 years to ensure the rammed earth structure stands tall for years to come. Here’s our how-to on rammed earth maintenance.

What you’ll need:

• Clean sponges
• Clean water
• ½" nap roller
• 5-gallon bucket
• Pump sprayer
• Muriatic acid
• Ammonia
• Tech-Dry Earth Binder
• Tech-Dry Stabilised Earth Water Repellent W

Step 1: Clean the rammed earth walls

Before the resealing process can begin, rammed earth walls may need to be cleaned, removing any unwanted efflorescence or other staining. Efflorescence is the process of salt leaching from the earth mixtures, causing chalk-like staining. If your rammed earth structure has accumulated staining, this process will help clean up your walls.

To properly clean each wall, you’ll need to use a muriatic acid and ammonia wash. Make sure to use gloves and protective eyewear during this step.

1. Begin by diluting the products using the ratios below:
   — 12oz Muriatic Acid to 1 Gallon of Water (1:10)
   — 8oz Ammonia to 1 Gallon of Water (1:16)
2. Spray muriatic acid dilution using a pump sprayer directly on a small section of the wall to ensure it doesn’t dry during the cleaning process.
3. Scrub the entire wall with a sponge to remove stains and efflorescence
4. Spray ammonia dilution while the wall is still wet, soaking to neutralize the muriatic acid.
5. While the wall is still wet, spray with a water hose from top to bottom to remove all the remaining muriatic acid and ammonia.
   — Sponge the wall with a clean sponge to remove any runs so they aren’t locked in with sealers.

Step 2: Apply Earth Binder

Once the walls have been cleaned and dried, it’s time to apply the Tech-Dry Earth Binder sealant. Earth Binder helps bind and seal internal and external walls from dust and residue, enhancing the texture, finish and color.

1. Begin by diluting the products using the ratios below:
   — 16oz Earth binder to 1 gallon of clean water (1:8)
2. Spray the Earth Binder dilution directly on the wall using a pump sprayer, soaking thoroughly from top to bottom.
3. Wet-on-Wet Application: Apply a second application once the first coat is absorbed and the wall is still wet.
   — Avoid excess accumulation or runs by backrolling with a ½" nap roller. This helps avoid streaking or an uneven finish.

Step 3: Apply Stabilised Earth Water Repellent W

After Earth Binder, it’s time to waterproof. Tech-Dry’s Stablised Earth Water Repellent W is a clear, water-based silicone sealer that makes rammed earth water repellent. This product is for exterior walls ONLY.

1. Begin by diluting the products using the ratios below:
   — 14.4oz sealer to 1 gallon clean water (1:9)
2. Spray Water Repellent using a pump sprayer and soak the wall section from top to bottom.
3. Wet-on-Wet Application: Apply a second application once the first coat is absorbed and the surface is still wet.
   — The number of coats depends on substrate permeability. Two coats is general recommendation, but it may require more for very permeable substrates.
   — Like the Earth Binder, avoid excess accumulation or runs by backrolling with a ½" nap roller. This helps avoid streaking or an uneven finish.

General maintenance of rammed earth structures should be expected, especially on structures without Plasticure. Earth Binder and Stabilised Earth Water Repellent should be reapplied to external walls every 3-5 years depending on weathering and climatic conditions.

How to get Tech-Dry® products

At Aussie Built, we’re committed to distributing the same products we trust ourselves. Tech-Dry products are essential to the success of our builds and we want to make them accessible to all rammed earth builders. As the exclusive U.S. supplier of rammed earth products for the construction and maintenance of earth structures, you can find the Tech-Dry lineup and more available in our online store.

Want to learn more?

For a deeper understanding of waterproofing, earth binding and maintenance of rammed earth structures, contact Aussie Built for consulting services on your next build.