Edge restraints, manufactured strips of high tensile-strength material that are installed around the perimeter of your paver project, are designed to keep the surface of your pavers in shape, quite literally. They’re created for engineering, not aesthetics, as they lie invisibly beneath the plane of the paver surface, yet they play a major role in preventing the aesthetics of your landscape project from deteriorating over time.
Even paver surfaces that won’t experience heavy loads or frequent traffic require edge restraints to maintain their structure and shape over time. Consider what could happen without these restraints: It’s possible for pavers around the perimeter to be pushed outward, as if they are “creeping” away from the center as time passes. The pavers more interior to the surface are partially stabilized by lateral compression imparted by pavers on all sides. But with no constraining force around the perimeter, any vertical load translates into lateral forces, and the stones around the edge will inevitably creep outward, shifting and destabilizing your entire layout.
What Exactly Are Edge Restraints?
An edge restraint is any rigid obstruction that resists lateral shifting of pavers outside their design perimeter. Traditionally that used to solely mean some kind of troweled concrete toe — a miniature, contiguous border wall buttressing the edges. But there’s a reason that more and more paver projects are built to a higher level of structural integrity and consistent quality — materials science has provided contemporary projects with a superior alternative: restraints pre-fabricated from PVC, aluminum, or steel.
These L-shaped strips are extruded from those materials, and they provide consistent, reliable lateral support along the outside contour of your patio, walkway, driveway, or other surface. Their effectiveness comes from both material strength and properly spaced spikes driven through the strips at a slight angle into the compacted base, securing both their position against the outside edge and resistance to lateral loads.
Concrete or Pre-Fab?
What’s better: concrete or something manufactured? Both will perform effectively provided that the edge restraint sits on the same base material as the rest of the installation. This is especially important in regions where the freeze-thaw cycle is a factor.
However, even in moderate climates, there are reasons to recommend the pre-fabricated option. First, these restraints install in dramatically less time. That means labor costs go down, while consistency goes up — you can be confident that the strength of manufactured material is evenly distributed around the paver perimeter. Another reason is for paver layouts that feature curved edges, pre-fab strips easily bend to conform. It’s true that the need for mounting spikes to secure restraining strips every 8 to 12 inches contributes to material costs, especially on jobs with a large footprint. Then again, spikes give your landscape contractor the flexibility to bolster restraining force when needed, by using tighter spacing. That’s crucial for higher load projects like driveways.
What’s the correct spacing for your project? That will vary with several factors, but no matter what your landscape contractor’s rule of thumb, Unilock can help confirm your project’s requirements, including a margin of safety for extra integrity. We support our partnering contractors, Unilock Authorized Contractors, their projects, and their clients, every step of the way.
Aside from the technical details of installation, there’s one more critical point in favor of manufactured edge restraints — they’re invisible once they’re installed. They won’t distract from the beauty of your project and the pavers you’ve chosen in any way. They remain essentially unseen, with their upper edge sufficiently below the surface plane to keep them hidden. Manufactured restraints let grass or other ground cover easily grow over them, so your landscape project blends seamlessly into the surrounding terrain. Having said that, a properly installed concrete edge will perform equally as well in this regard.
Knowing What’s Under Your Pavers
Even when everything is done right, from the bedding to the joint compound and paver compaction, creeping edges are a concern. When installed properly, edge restraints can be a strong defeater of surface deformation, making your installation last longer, while retaining its original shape and the overall integrity of the layout.
That force pushing outward can produce unpredictable effects across the entire project surface, producing multiple sites of upturn, cracking, and dislodgement — not just near the edges but in a domino effect, toward the interior. It’s better to prevent lateral shifts from the start than to try to address mounting repair issues as they appear.
Your Unilock Authorized Contractor can discuss trade-offs of concrete versus manufactured restraints with you. In addition to connecting you with landscape contractors we trust, Unilock offers resources like our design catalog to inspire, educate, and help you visualize your next outdoor living project. It’s one of the many ways we support you through every step of the landscape design and build process.