Common Mistakes in Covered Linkway Design

Covered linkways are a staple in public and residential developments across Singapore, providing sheltered connections between buildings, transport nodes, and communal amenities.

While they may seem like straightforward structures, poor detailing or coordination can lead to major functional and maintenance issues down the line.

Based on common pain points observed in practice, here are seven key mistakes to avoid when designing covered linkways — especially those with free-fall roofs discharging to house drains.

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1. Overcomplicating Roof Geometry with Curved Structures

While curved linkway roofs may appear more elegant, they introduce complexity at intersections. When connecting to other perpendicular roofs, a seamless connection is hard to achieve without:

• Having a separate roof at the connection, or

• Raising the height of one roof to allow rainwater to fall cleanly onto another (i.e., free-fall principle).

Good Practice: Use simple pitched roofs for easier interfacing. This allows for clearer rain discharge routes and simplifies structural and flashing details.

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2. Roofs should not follow ramp gradients without Proper Roof Discharge

It may seem logical to follow the slope of an accessibility ramp with the linkway roof, but without a proper rain discharge strategy, water can stagnate.

Why It’s a Problem:

• No gutters are allowed (due to mosquito breeding risk per NEA regulations).

• Sloped roofs without fixed discharge levels may direct water back toward pedestrian walkways.

Good Practice: Maintain a fixed roof level independent of ramp gradients. Let rainwater discharge via eaves away from the walkway, with downflow directed to adjacent drains.

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3. Inadequate Sections — Especially at Building Interfaces

Failing to draw enough sections, particularly where the linkway connects to a building, often results in unclear flashing details.

Result: Contractors may improvise or dispute missing information, leading to water ingress or compliance issues.

Good Practice: Cut detailed cross and longitudinal sections showing roof-to-wall connections, flashing, and junction details clearly.

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4. Misaligned Roof Eaves and House Drains

When the eave of the linkway roof doesn’t line up with the house drain, rainwater splashes onto walkways instead of being captured effectively.

Good Practice: Align the drip edge of the roof directly over the house drain, ensuring water falls cleanly into it.

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5. Inadequate Coverage from Rain

A frequent complaint is that rain still gets into covered walkways due to poor sizing or misalignment of the roof.

Good Practice: Design for lateral rain (driven by wind) by ensuring:

• Sufficient roof width and overhang (exceeding 1:1 ratio of height and width)

• Vertical rainscreen can be added to mitigate wind-blown rain from side directions.

• Consider prevailing wind directions in your orientation of linkways to mitigate wind-driven rain.

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6. Incorrect Column Positioning

Columns that are too close to the edge of the roof may lead to constructability issues or affect flow of rainwater.

Good Practice: Set columns at least 300–600mm inboard from the roof eaves to allow for proper overhang, maintenance access, and visual clarity.

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7. Roof Eaves Too Close to Driveways

If the eaves of a low linkway roof overhang too close to driveways, they are at risk of vehicular damage (e.g., by tall vans or service vehicles).

Good Practice: Maintain a minimum 600mm setback between the eave and any vehicular path. Coordinate with traffic movement paths and height clearances.

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Final Thoughts

Designing covered linkways requires an appreciation of function, maintenance, and alignment with urban infrastructure. Many of these mistakes stem from insufficient coordination between architectural, civil, and structural inputs — so early-stage cross-discipline reviews are key.