Stabilizing Decorative Structures on Pavers
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One question I often get is, "Now that my pavers are installed how do I secure a pergola on top of them?" That is the wrong time to think about what needs to be done to stabilize structures that sit on top of pavers. That should be a consideration from the outset of the construction planning. In order to anchor a gazebo, pergola, or any other framed structure on top of pavers, it must be integrally connected to poured-in-place concrete pier footers. Trying to stabilize any of these structures by merely attaching them to the pavers will result in nothing more than token resistance to the lateral force load pressures produced by strong or gusting winds. The structural integrity of an anchoring system is achieved during the construction of the paver installation by digging cylindrical holes that are 18" to 24" in diameter and deep enough to go below the frost line on a ground level patio. After the pier footer is excavated, place sections of Sonatube or corrugated plastic pipe vertically into the excavated areas. Those areas need to level with the final grade of the base material. I suggest that the pipe or Sonatube sections be cut a little longer than needed so that once in place they can be checked for proper elevation with a transit, marked accordingly and cut to the exact height. It is also a good idea to identify each one with an individual number so that after removing the sections for their final cut each unit is returned to the spot where it has been tailored to fit. This same pier footer system can also be installed during the construction of a raised patio by incorporating the Sonatube or corrugated plastic pipe sections into the compacted dense graded aggregate that is used to fill the cavity of the raised patio. As the elevation of the construction is raised up and encompasses the Sonatubes, care must be taken not to dislodge nor tilt the tubing or pipe. Stabilizing the units will be hardest when the first lifts of dense graded aggregate are spread and compacted. Proper compaction must be achieved around the each tube or pipe to avoid settlement later on. Anchor bolts, all-thread, or some kind of hardware worthy of securing and stabilizing a structure must be set into the concrete while it is still wet. The anchors are set in a vertical position unless the structure requires an angle particular to the structure. Care should be taken that piers and anchor bolts are set with the exact dimensions of the structure to be anchored in mind as the anchor positions cannot be adjusted after the piers have been poured. As the pavers are installed over the surface, holes will have to be drilled into as many pavers as there are anchor bolts in order to fit over the vertical anchor bolts. Once all of the pavers are in place and completely installed the structure can be set in place and bolted down securely. This stabilizing system will provide structural integrity and prevent the structure from becoming dislodged or tipping over. When the next strong wind blows over the patio furniture and the pergola has not budged, you and your customer will appreciate the extra steps taken in your construction. Mark S. Antunes Technical Information Manager, Hardscaping
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