He Spent $7,000 Turning the Space Under His Deck Into a Flagstone Patio
Most homeowners leave the space beneath an elevated deck as bare grass or gravel. Reddit user u/stenbough spent about $7,000 and three months turning his into a hand-built flagstone patio. Working almost entirely without heavy machinery, he excavated the area by hand, installed a compacted stone base, and fit irregular Pennsylvania flagstones into a surface that looks more like natural bedrock than a typical backyard patio.
About $3,200 of the budget went toward three pallets of Pennsylvania flagstone. A borrowed plate compactor handled the base, while an angle grinder, hammer, chisel, and patience shaped the finished patio. Reddit users praised the tight joints and natural appearance, with many calling it one of the best DIY flagstone installations they had seen.
The Patio Started With Spray Paint and a Shovel
The project began by outlining the patio with curved edges beneath the elevated deck. The homeowner removed the existing sod and dug out the entire footprint by hand instead of building over the grass.
The sweeping outline extended beyond the deck posts, creating enough room for seating while connecting naturally with the surrounding lawn.
Every Inch Was Excavated by Hand
After removing the grass, the entire patio area was excavated several inches deep to prepare for the compacted base. Piles of soil surrounded the work area while a Gorilla Cart handled most of the hauling.
The homeowner explained that everything was dug, raked, carried, and moved by hand, relying on a borrowed plate compactor only after the excavation was complete.
Three Pallets of Pennsylvania Flagstone Arrived First
The largest material expense came from three pallets of irregular Pennsylvania flagstone stacked on the driveway before installation.
Rather than using manufactured pavers, the homeowner selected natural stone because the backyard overlooks a pond, and the irregular shapes matched the landscape better than straight-edged concrete pavers.
The Base Went Down Before Any Stone
After excavation, the patio received layers of compacted aggregate that created a stable foundation beneath the flagstone.
Gravel covered the entire footprint while grade stakes marked the outside curves. New evergreens and a weeping ornamental tree were positioned before the stone installation reached them, allowing the planting beds and patio to fit together as one design.
Every Flagstone Was Laid Out Before Installation
Instead of setting one stone at a time, the homeowner spread dozens of flagstones across the prepared base to find the best arrangement. The largest pieces established the perimeter while the remaining stones filled the center.
Once the overall layout looked balanced, each stone stayed in place until the trimming stage created consistent joints across the patio.
The Patio Started Looking Like One Continuous Surface
The irregular flagstones now fit together with narrow, consistent joints instead of wide gravel gaps. Dark joint compound filled the spaces between the stones, creating the appearance of one continuous paved surface while preserving the natural shape of each piece.
The homeowner used NOCO by Techniseal, a hardening joint compound chosen instead of loose sand. Reddit users praised the tight spacing, with several calling it one of the best DIY flagstone patios they had seen
The Finished Surface Looked Like Natural Bedrock
Once every stone sat level, the irregular shapes created a continuous surface instead of isolated stepping stones.
The patio stretched beneath the full width of the deck while the surrounding landscape framed the stone without sharp transitions.
Fresh Landscaping Softened the Stone
Curved planting beds wrapped around the patio using mulch, shrubs, ornamental grasses, and a small weeping tree.
Instead of straight borders, the beds followed the same flowing lines established by the flagstone, making the patio appear integrated into the backyard rather than added afterward.
Every Deck Post Was Worked Into the Layout
The stone installation wrapped tightly around each structural post supporting the deck above.
Rather than cutting the patio into separate sections, the flagstone continued beneath the entire structure, creating one uninterrupted outdoor living area with space for grilling, seating, and movement.
String Lights Finished the Outdoor Room
After the stonework was complete, the homeowner painted the deck framing dark, added café string lights beneath the joists, and furnished the patio with wood-framed seating and a hanging chair.
The formerly empty space beneath the deck became the primary outdoor gathering area while the upper deck remained available for dining.
The Before and After Shows Every Step Paid Off
The original backyard contained nothing more than grass beneath the raised deck.
Three months later, the space became a finished flagstone patio surrounded by landscaping, lighting, and outdoor furniture. Reddit users praised the precise stone fitting, consistent joints, and natural appearance, with many commenting that it outperformed professional installations they had seen.
All image credits go to Reddit user u/stenbough.