We are Your Hillsboro Retaining Wall Construction Company

Hillsboro’s position on the floor of the Tualatin Valley means that retaining wall construction here contends with some of the heaviest, stickiest clay soils in the Pacific Northwest. The Missoula Flood deposits that blanket the valley to depths of several hundred feet create a construction environment where water management is the defining challenge of every retaining wall project. Prodan Construction builds retaining walls throughout Hillsboro — from the massive new developments in South Hillsboro to the established neighborhoods near downtown and Orenco Station — with drainage engineering specifically calibrated for the Tualatin Valley’s demanding clay conditions. Our experience with these soils across dozens of Hillsboro projects means we know exactly how to build walls that perform in ground where lesser construction sinks, tilts, and fails. Call (503) 773-6949 for your free Hillsboro retaining wall consultation.

A Good Retaining Wall Needs a Solid Construction at All Levels

It surprises homeowners when they learn that the flat terrain of Hillsboro can be just as challenging for retaining wall construction as the steep hillsides found elsewhere in the metro. The Tualatin Valley clay — classified as 20 to 35 percent clay content in the Willamette series — becomes nearly unworkable when wet, expanding significantly and generating lateral pressures that can exceed anything found in rock-based soils. When it dries, the same clay shrinks and cracks, creating voids that fill with water during the next rain cycle. This constant expansion and contraction makes retaining wall foundation stability an ongoing challenge that must be engineered into the design from the beginning.

Retaining wall foundations in Hillsboro require over-excavation well below the clay’s active zone and replacement with compacted angular gravel that will not heave with seasonal moisture changes. We typically install ten to twelve inches of base material in Hillsboro — more than standard specifications call for — because we have seen firsthand what happens to walls that sit on a thinner pad in this clay. The drainage system behind the wall must handle not just surface runoff but the seasonal release of stored water from the clay itself, which can generate surprising volumes during extended dry periods following wet seasons. The first course anchors below grade, and geogrid reinforcement is used more aggressively in Hillsboro than in many other areas because the clay’s expansive forces demand it.

As South Hillsboro continues its historic build-out of over 3,000 homes, retaining walls are an essential component of the infrastructure making that development possible. Prodan Construction serves both the subdivision-scale developers and the individual homeowners throughout Hillsboro who need retaining walls built to handle the Tualatin Valley’s uniquely challenging soil conditions.

Prodan Construction is Your Hillsboro Retaining Wall Repair Company

Hillsboro’s heavy clay takes a predictable toll on retaining walls that were not built with adequate drainage: the walls lean, crack, and ultimately fail as years of moisture cycling progressively displaces the structure from its foundation. Prodan Construction repairs and rebuilds failing retaining walls across Hillsboro, and in every case, the repair begins with correcting the drainage deficiency that allowed the clay to overwhelm the original wall. We remove failed walls, re-excavate to stable material, install modern drainage systems, and rebuild with materials and reinforcement designed for the Tualatin Valley’s specific clay characteristics. If your Hillsboro retaining wall is showing signs of movement, contact us at (503) 773-6949 — these problems accelerate with each seasonal moisture cycle.

What People We’ve Worked with have to Say About Us

Hillsboro property owners choose Prodan Construction for retaining wall work because we deliver walls that actually last in the Tualatin Valley’s challenging clay. Our five-star reputation is built on honest engineering and durable construction. Here is what our clients have to say:

Cody K. — “Prodan and his team were great to work with! They were very professional and did an amazing job on our retaining wall. The wall looks fantastic and has held up perfectly. Highly recommend Prodan Construction to anyone in need of a retaining wall or any other construction work.”

Ashley B. — “We had Prodan Construction build a retaining wall in our backyard and we couldn’t be happier with the results! The crew was punctual, hardworking, and respectful of our property. They completed the project on time and on budget. The wall is solid and looks amazing. Thank you Prodan Construction!”

Vickie D. — “Prodan Construction did an outstanding job on our retaining wall project. From the initial consultation to the final walkthrough, they were professional and communicative every step of the way. The quality of their work is evident in the finished product. We would absolutely hire them again.”

Lon M. — “I hired Prodan Construction to replace an old failing retaining wall on my property and they exceeded my expectations. The new wall is rock solid and looks incredible. Their team was knowledgeable, efficient, and left the site cleaner than they found it. Five stars all the way.”

Our Hillsboro Retaining Wall Construction Company FAQ

How do you build a retaining wall?

Retaining wall construction in Hillsboro must account for the extremely challenging Tualatin Valley clay soils. Our standard process includes:

• Foundation preparation: We excavate to stable bearing material and install a compacted gravel base that provides both structural support and drainage for the wall footing.
• First course and base construction: The first course of block, stone, or concrete is set below the finished grade to anchor the wall and resist lateral sliding forces from the retained earth.
• Wall construction with drainage: Each course is built with proper setback (batter) and backfilled with drainage aggregate. Perforated pipe at the base collects and redirects groundwater away from the wall.
• Reinforcement and backfill: For taller walls, geogrid reinforcement layers tie the wall into the retained soil mass. Final backfill is compacted in lifts to prevent settlement.
• Drainage completion and grading: Surface drainage is directed away from the wall, drain outlets are verified functional, and the site is graded to finished specifications.

Do I need a structural engineer for a retaining wall?

The City of Hillsboro issues building permits for retaining walls exceeding four feet in exposed height. South Hillsboro has specific development agreement requirements that may affect wall specifications. Hillsboro updated its Design and Construction Standards in 2025, and walls in newer developments must comply with these current standards. Structural engineering is advisable for any Hillsboro wall built in the heavy valley clay, as the expansive forces can exceed standard design assumptions. Prodan Construction handles permitting and engineering coordination for all our Hillsboro retaining wall projects.

How do you know when you need a retaining wall?

The signs that you need a retaining wall in Hillsboro often relate to the clay soil’s seasonal behavior. Yard areas that become swampy in winter and crack in summer, property lines where one lot sits notably higher than the adjacent one, driveways that have developed humps or dips from soil movement, and foundation walls showing new cracks — particularly horizontal cracks in poured concrete foundations — all suggest that the clay is moving and structural intervention is needed.

In Hillsboro’s newer developments, retaining walls also serve important grade-transition functions between homes at different elevations within subdivisions. A quality retaining wall establishes clear, stable boundaries between properties while managing the drainage that would otherwise flow from higher lots onto lower ones. In South Hillsboro’s planned communities, these walls are part of the essential infrastructure that makes the neighborhood function properly.

How long do retaining walls last?

With proper construction and drainage engineering, retaining walls in Hillsboro can deliver 50 to 75 years of service. The Tualatin Valley clay is more demanding on wall structures than soils in most other areas because its constant expansion and contraction creates fatigue stresses that accumulate over time. Walls with robust, well-maintained drainage systems last significantly longer than those whose drainage has been compromised, because the drainage controls how much the clay can expand against the wall. Prodan Construction specifies heavy-duty drainage components for all Hillsboro installations and recommends periodic inspection to ensure drainage outlets remain functional over the decades.

What are the types of retaining wall?

For Hillsboro’s heavy clay terrain, the most effective retaining wall types are:

• Brick/Block retaining walls: Interlocking segmental retaining wall blocks that are engineered for strength, available in multiple styles, and designed for efficient installation with built-in connection systems.
• Concrete retaining walls: Poured-in-place reinforced concrete walls that provide maximum structural strength for the most demanding applications, including tall walls, heavy surcharge loads, and steep terrain.
• Rock/Boulder retaining walls: Natural stone and boulder walls that provide a rugged, organic appearance while delivering substantial structural capacity, particularly effective on larger rural and semi-rural properties.

Gabion and timber walls are generally less effective in Hillsboro due to the persistent clay moisture that accelerates material deterioration. Concrete and engineered block systems provide the best long-term value in the Tualatin Valley’s demanding soil environment. Prodan Construction will assess your specific Hillsboro site and recommend the wall type that provides the optimal combination of structural performance and long-term durability.

Hillsboro’s Tualatin Valley clay soils create retaining wall challenges that demand specialized engineering and construction expertise. Prodan Construction has built the local knowledge and technical capability to deliver walls that perform in these demanding conditions. Call (503) 773-6949 or contact us online to schedule your free Hillsboro retaining wall estimate.

Prodan Construction is Your Hillsboro Retaining Wall Construction Company