Flagstone Patio Repointing and Drainage Correction in Potomac, MD
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Scope of Work
Project Overview
The homeowner originally installed this Pennsylvania bluestone patio themselves, setting the stones on a solid concrete base with polymeric sand in the joints. Over time, heavy rain and pooling water broke the sand down, leaving the joints wet and sunken.
We cleared out the failing polymeric sand and repointed the patio with high PSI mortar across the upper patio, roughly 400 square feet, and a smaller 60 square foot area near the shed. We also regraded the stones in front of the shed so water drains away from the door instead of collecting against it.
Before / AFTER
Site Conditions
The Property and Site Conditions
The patio had a solid foundation working in its favor. Because the stones sat on a concrete base, the structure underneath was sound, and the problems were limited to the joints and the surface grading.
The polymeric sand was the main issue. It had absorbed water and sunk below the stone surface, and several stones had shifted enough to create tripping hazards across the main patio area.
The smaller section in front of the shed had a separate problem. The stones were graded toward the shed door, so rainwater pooled at the entrance and put the structure and anything stored inside at risk of moisture damage.
ASSESsMENT
What We Did
Before repointing, we dug out the old polymeric sand from the joints across both patio areas, working around the existing brick border. Clearing the joints completely gave the new mortar a clean surface to bond to.
During the work, we tamped down the stones that had shifted out of level so the walking surface sat flat again. We then filled the joints across both areas with high PSI mortar, which holds up to rain and erosion far better than polymeric sand on a patio like this one.
At the shed, we lifted the stones in front of the door and regraded them to pitch water away from the entrance and toward a nearby walkway with underlying drainage. The repointed joints now lock the stones in place, the surface is level underfoot, and water moves away from the shed instead of pooling at the door.
Completed Project
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