On a concrete rooftop, the trick is to stop thinking about fixing furniture to the slab and start thinking about weight, friction, and wind. Drilling is usually the wrong answer anyway: it can puncture waterproofing, crack coatings, and create leak paths. A non-penetrating system is safer for the roof and often just as effective if it is designed properly.
First, confirm what the roof can carry. Rooftop furniture, planters, and ballast add dead load, and wind can add uplift and sliding forces. Ask the building owner or a structural engineer about load limits and permitted anchoring methods. Also check house rules; many buildings prohibit tying anything to railings, especially if the railing is not rated for lateral load.
Use weighted bases as the primary anchor. Choose furniture with hollow bases or ballast trays that accept sandbags, gravel bags, or water ballast. Water is convenient but freezes and evaporates, so check it seasonally. Sand or gravel is heavier and more stable. Spread weight over a large area with load-distributing pads rather than concentrating it on small feet. Rubber or neoprene pads under legs improve friction and protect the concrete coating.
Create a low-profile, wind-smart layout. Keep sofas and tables close to the deck, avoid tall lightweight pieces, and group furniture in sheltered corners rather than along exposed edges. Use interlocking or modular pieces, or connect individual items to a common weighted base with straps or brackets. Umbrellas are the biggest risk: use heavy, non-penetrating umbrella bases, and close or remove canopies when high winds are forecast. Never rely on a table alone to hold an umbrella.
If you need extra restraint, use proprietary non-penetrating anchors that rely on ballast and friction, or tether furniture to an approved existing structural point—not to a glass railing, loose pipe, or parapet. Use galvanized or stainless hardware, and inspect straps regularly. Avoid adhesives as a primary anchor; they can fail on dirty, wet, or coated concrete and may damage the surface when removed.
Finally, protect the roof and keep the system maintainable. Use outdoor-rated, UV-stable materials, avoid sharp edges on weights, and check ballast after storms. If in doubt, have a local engineer or roofing contractor review the plan. Done well, a no-drill rooftop setup can be stable, reversible, and kind to the building.