How to Build an Interlocking Retaining Wall

Build a strong, stylish retaining wall without mortar. We'll show yous how.

Published on June 15, 2018

  • Total Time: 15 hours
  • Skill Level: Intermediate

Interlocking concrete block is a way to build a strong wall without mortar. Some such blocks are fabricated with flanges that slip over the rear edge of the preceding course; others rely on a organisation of pins. With both types, you don't have to practise throwing mortar or setting block, but you will become an attractive add-on to your landscape. The flanges slope the wall dorsum into the gradient for boosted strength.

Interlocking-cake walls don't require a basis, simply some styles require you to fix the start course in a trench to hold the bottom of the wall in place. Cut the slope back 12 to 15 inches from the rear of the trench to go out room for gravel backfill and a drainpipe—a must for retaining walls. Save the topsoil and utilize whatever extra as make full elsewhere in your landscape.

To lay a 3x16-human foot wall, expect to spend 10 to 20 hours. You'll demand to feel comfortable digging, designing a layout, leveling, and laying brick. Before y'all begin, phone call your local hotline to mark whatever clandestine utilities.

Instructions

  1. Lay Out Wall

    Lay out the wall and remove the soil from the gradient. Post-obit the manufacturer'southward recommendations, dig and level a trench for the first course. Stake a mason's line to assistance align the blocks.

  2. Spread Landscape Fabric

    Starting a foot beyond the height border of the slope, spread landscape textile down and over the trench. Put stones on the tiptop to concord the fabric in place. Overlap the fabric edges by 6 inches. Tamp 3 to 4 inches of gravel into the trench and back to the bottom of the excavation.

  3. Lay First Course

    Using the line or the edge of the trench to guide you lot, lay the showtime form in the trench. The first course blocks are set up backwards for many styles. Prepare each block with a prophylactic mallet. Make sure each cake is level front to back and with the adjoining blocks. Use a iv-foot level to check—shorter levels are non long enough to ensure accurateness. If you need less than a full block at the end of the wall, lay smaller blocks or trim full blocks to fit.

    Editor'due south tip: Precast block is trimmed the same fashion other masonry materials are trimmed. If you're using solid block, score the line yous want to cut with a brick ready and minor sledgehammer. Repeated blows will split the block. Hollow-core blocks don't break cleanly. Buy half blocks and smaller blocks to fit where you need them, or cut them with a masonry blade.

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    Set up Remaining Courses

    Set the remaining courses with the flanges tight confronting the back of the preceding course. Showtime every other form with a one-half or fractional block then the joints are offset by at least three inches or the amount specified past the manufacturer's instructions. Equally you work, check the blocks for level. Shim the low end of a block with a small piece of cedar shingle.

    Editor'due south tip: Some blocks have pin-lock systems (run into illustration, above). Ane of the nearly mutual employs vertical and horizontal pins. Blocks fit over the vertical pins as you lay them. After laying each course, horizontal pins lock the blocks laterally.

  5. Gear up Drainpipe

    Afterwards the third course of block, backfill the surface area between the wall and the slope with gravel, just virtually fifty-fifty with the 2nd course. Lay in a perforated plastic drainpipe on the gravel (holes downwardly). Let the pipe daylight across the edge of the wall, or run information technology into a French drain.

    Editor's tip: If your wall is designed with corners, the corner blocks must overlap at the joints to tie the ii legs together. Cutting half blocks and alternate them with full blocks as shown, following the manufacturer'south instructions. Chisel off the lip of the block if it gets in the fashion. As y'all place the block, strengthen the bond with a bead of construction adhesive.

  6. Backfill Wall

    As you build the wall, backfill gravel backside information technology at least every other form, covering the pipe and bringing the level of gravel up merely below the top of the terminal form y'all laid.

  7. Tuck Textile

    Using the aforementioned techniques and starting every other row with a partial block, continue building the wall and backfilling it with gravel. When you're one or 2 courses beneath finished height, fold the landscape cloth over the gravel and tuck it behind the block.

  8. Tamp Soil

    Shovel about ii inches of the topsoil you removed (non the subsoil at the base of the slope) on top of the landscape cloth. Tamp the soil lightly with a garden rake and replace the sod.

  9. Apply Adhesive

    The capstones fabricated for block of this or a like shape embrace the V-shaped gaps between blocks in the lower courses. Set up the next-to-concluding course by applying a bead of structure adhesive on the surface of each block.

  10. Identify Capstones

    Post-obit the manufacturer'due south instructions identify the form of capstones on the wall.

  11. Cease Base of operations

    If you're not building a patio or other structure below the wall, spread and tamp the topsoil you removed from the excavation. Fill in around the base of operations of the wall and level the soil as far forrard from the base of operations as the landscape allows. Tamp the soil and supercede the sod. Water the sod frequently until it is well established.