Retaining wall block selection comes down to four real choices for DIY work: segmental concrete blocks, natural stone, pressure-treated timber, or poured concrete. Each has a wall height range it serves well, a labor reality, and a long-term failure mode. This guide compares the four by the criteria that actually predict whether the wall will still be straight in 20 years.
What a retaining wall has to do
Any retaining wall has to resist three forces from the soil behind it:
- Lateral earth pressure from the weight of the soil pushing horizontally
- Hydrostatic pressure from water in the backfill
- Surcharge loads from anything sitting on top of the retained soil (driveway, parking pad, structures)
The wall handles these forces through its own weight (gravity walls), through reinforcement extending back into the retained soil (reinforced walls), or through a footing and stem that resists overturning (cantilever walls).
For DIY scale (walls 4 feet or shorter), gravity walls handle the job and all the materials below work as gravity walls. Above 4 feet, walls typically need geogrid soil reinforcement and engineered design.
Segmental concrete blocks
Segmental retaining wall blocks (SRW blocks) are the standard DIY choice. Brands include Versa-Lok, Allan Block, Pavestone (Anchor), Belgard, and many regional manufacturers. Common sizes range from 6 inches tall by 12 inches wide for landscape walls up to 8 inches tall by 18 inches wide for structural walls.
The defining feature is a built-in mechanical interlock. Most blocks have either a back lip that hooks behind the block below, or pin holes that accept connecting pins. The interlock automatically creates a slight setback (typically 1/4 to 1 inch per course) that leans the wall back into the slope for added stability.
Best for: Walls 1 to 4 feet tall. Predictable DIY results. The fastest material to install.
Pros: Uniform size. Built-in setback. Stack dry without mortar. Predictable cost. Available at every big-box garden center.
Cons: Concrete appearance that some people find less attractive than natural stone. Specific brands may discontinue and limit future repairs.
Cost: 25 to 45 dollars per linear foot of wall face for a 3 foot tall wall.
Natural stone
Natural stone walls use cut stone (squared and dimensioned), random rubble (irregular stones), or boulders. Stones can be dry-stacked or mortared.
Dry-stacked stone walls rely on careful stone-to-stone fit, weight, and friction. The art of building one is in selecting and placing stones so their weight pins lower stones in place and so the wall battered (leaning) into the slope.
Mortared stone walls use the stones for facing and mortar for binding. They look like dry-stacked walls but behave more like poured concrete walls. They are less forgiving of frost movement and require properly designed footings.
Best for: Walls where appearance is the primary goal. Walls in formal landscape designs. Walls with budget for materials or skilled labor.
Pros: Distinctive appearance. Long lifespan if dry-stacked correctly. Stones can be reused if the wall is rebuilt.
Cons: Each stone requires individual fitting, making the labor 3 to 5 times longer than equivalent SRW block work. Quality dry-stacking is a learned skill. Sourcing stone in some regions requires special order.
Cost: 60 to 150 dollars per linear foot of wall face for a 3 foot tall wall, depending on stone choice and region.
Pressure-treated timber
Timber retaining walls use 6x6 or 8x8 pressure-treated landscape timbers stacked horizontally and pinned through with rebar or long screws into the ground or into deadmen (perpendicular timbers extending back into the slope).
Treated timber walls were the default 1980s and 1990s residential retaining wall. They are still allowed in most areas but have largely been replaced by SRW block for new walls.
Best for: Short walls (under 3 feet) in informal landscapes. Replacing existing timber walls where matching appearance is preferred.
Pros: Lower material cost. Faster to install than stone. Familiar materials for many DIYers.
Cons: Shortest lifespan of any retaining wall material at 20 to 30 years. Treated timber chemicals leach into soil, restricting use near vegetable gardens. Increasingly hard to source 6x6 ground-contact-rated landscape timbers in some regions.
Cost: 15 to 25 dollars per linear foot of wall face for a 3 foot tall wall.
Poured concrete
Cast-in-place concrete retaining walls require formwork, rebar, and a concrete pour. The wall is a continuous structural element, typically with a footing wider than the stem.
Poured concrete walls are common above 4 feet of height and on tight property lines where every inch of footing matters. Below 4 feet, the formwork labor usually makes SRW block or stone more economical.
Best for: Walls above 4 feet (with engineering). Tight space constraints. Foundation-integrated walls.
Pros: Highest structural capacity per inch of wall thickness. Smooth uniform appearance. Long lifespan.
Cons: Formwork is technical and the concrete pour cannot be staged easily. Cracking is common without proper joints. Most demanding DIY option of the four. Often requires concrete pump trucks for access.
Cost: 50 to 90 dollars per linear foot of wall face for a 3 foot tall wall, much higher with pumping or tight access.
Drainage applies to all of them
Regardless of which material you choose, the wall needs proper drainage behind it. The basic requirements:
- Gravel backfill (3/4 inch crushed stone, not pea gravel) extending at least 12 inches back from the wall face
- Geotextile fabric between the gravel backfill and the native soil to prevent soil from migrating into the gravel
- Perforated drain pipe at the base of the gravel backfill, sloped 1 to 2 percent to daylight at one end
- Footing or base course of 4 to 6 inches of compacted crushed stone below the bottom block, stone, or timber
Skip the drainage and the wall will fail at year 2 to 5 from frost heaving and hydrostatic pressure, regardless of material.
See the methodology page for our hardscape evaluation approach. Pair this guide with the paver patio installation article and the french drain installation guide for a complete backyard hardscaping sequence.
Frequently asked questions
What is the tallest retaining wall I can build without an engineer?+
Most municipalities allow DIY retaining walls up to 3 to 4 feet tall measured from the bottom of the lowest exposed block to the top of the wall. Walls above this height typically require an engineered design and a permit. The height limit exists because the lateral soil pressure on a wall increases roughly with the square of the height. A 6 foot wall has about 4 times the lateral pressure of a 3 foot wall. Above 4 feet, geogrid soil reinforcement, deeper footings, and engineered block placement become necessary. Check your local code before starting any retaining wall over 2 feet tall.
Segmental concrete blocks vs natural stone: which is better for DIY?+
Segmental concrete blocks (Versa-Lok, Allan Block, Pavestone, etc.) are easier for DIY because they are uniform in size, have built-in lips or pins that lock courses together, and stack quickly without mortar. Natural stone walls take 3 to 5 times longer to build because each stone needs individual fitting and may need mortar or careful dry-stacking technique. Cost is similar per square foot of wall face. Choose segmental concrete for DIY speed and predictable results. Choose natural stone if appearance matters and you have time or are hiring out the labor.
Do retaining walls need a French drain behind them?+
Yes for any wall over 2 feet tall, and recommended for walls of any height. Soil behind a retaining wall holds water. That water creates hydrostatic pressure on the wall, which can be many times the dry soil pressure. A French drain (perforated pipe in a gravel backfill, sloped to daylight) relieves the water and prevents the pressure buildup. Skip the drain on a wall over 2 feet tall and the wall will bow, lean, or fail within 2 to 5 years. The drain costs about 10 percent of the total wall material budget and pays for itself in longevity.
How much does a retaining wall cost per linear foot?+
Materials only for a 3 foot tall wall: segmental concrete block 25 to 45 dollars per linear foot. Natural stone 60 to 150 dollars per linear foot depending on stone choice. Timber (pressure-treated 6x6) 15 to 25 dollars per linear foot but with shorter lifespan. Poured concrete 50 to 90 dollars per linear foot. Hiring a contractor adds 30 to 70 dollars per linear foot for labor depending on region and access. Materials roughly double for a 4 foot tall wall because of additional courses, longer backfill, and increased base requirements.
How long do retaining walls last?+
Segmental concrete blocks: 50 to 100 years if properly drained. Natural dry-stacked stone: 100 plus years with periodic resetting of frost-heaved stones. Mortared stone: 50 to 75 years before the mortar joints need repointing. Timber (pressure-treated 6x6): 20 to 30 years before rot begins. Poured concrete: 50 to 75 years. The actual life depends entirely on drainage. A wall with a working French drain and proper backfill outlasts a wall with poor drainage by 3 to 5 times regardless of the material chosen.
Morgan Davis
Morgan Davis writes for The Tested Hub.