Keystone Retaining Wall Installation Guide

A Comprehensive Guide to Keystone Retaining Wall Installation

Keystone retaining walls are a versatile and durable way to create beautiful and functional outdoor spaces, and their installation can be a straightforward process with the right preparation and technique. Here's a detailed guide to help you through the essential aspects of keystone retaining wall installation:

1. Site Preparation

Begin by marking the outline of the wall and excavating the area to a depth of 8-12 inches below the intended wall height. Compact the soil at the bottom of the excavation and install a layer of crushed gravel or paver base for drainage. This base layer should be at least 4 inches thick and compacted thoroughly.

2. Base Course Installation

The first course of keystone blocks forms the base of the wall and requires special attention. Start by laying a level bed of mortar or polymeric sand on the prepared base. Place the first course of blocks on the mortar or sand, ensuring they are level and plumb. Use a rubber mallet to tap the blocks into place.

3. Keying the Blocks

Keying refers to interlocking the keystone blocks to enhance stability. Each block has projections that fit into recesses on adjacent blocks. As you stack the wall, alternate the orientation of the blocks so that the projections and recesses align, creating a strong interlocking bond.

4. Wall Alignment and Stability

Maintaining the wall's alignment and stability is crucial. Use a string line or level to regularly check the wall's height and verticality. To prevent the wall from leaning or bowing, install geogrid reinforcement every few courses. Geogrid is a fabric material that helps distribute weight and improve soil stability.

5. Backfilling and Compacting

As you build the wall, backfill the excavated area behind it with crushed gravel or soil. Compact the backfill in layers of 6-8 inches to ensure proper drainage and support. The backfill should be compacted to approximately 90% of its maximum density.

6. Drainage

Proper drainage is essential to prevent water buildup behind the wall, which can cause it to fail. Install a perforated drainage pipe along the base of the wall on the backfill side. Extend the pipe to a suitable drainage point, such as a storm drain or dry well.

7. Capstones and Finishing

The final step is to install the capstones on top of the wall. Capstones are larger blocks that protect the wall from the elements and provide a finished look. Use mortar or polymeric sand to set the capstones in place and ensure they are level and secure.

Keystone retaining walls are a great way to create attractive and functional outdoor spaces. By following these steps, you can ensure a successful and durable installation that will enhance your property for years to come.