Maintenance and Repairs

November 12, 2025 Published by Golden Horseshoe Chapter - By Kaezad Wania

What You Don’t See - Why Riser Expansion & Support Systems Matter

From the Volume 25, Fall 2025 issue of the CCI GHC Condo News Magazine

Behind drywall and sleek interior finishes of every high-rise condominium lies a network of vertical piping systems known as risers. This piping infrastructure is responsible for circulating water for domestic, potable and heating/cooling systems in buildings. While residents may never see these systems, their performance is critical to daily comfort and long-term asset value. One of the most overlooked, but vital aspects of riser performance is how they are supported and allowed to expand or contract in response to changes in fluid temperature. Improper expansion allowances or inadequate support can lead to pipe stress, joint failure, water damage, and costly repairs. In this article, we’ll explore what riser expansion and support systems are, why they matter, the common challenges faced in retrofitting these systems, and the recommended steps that condominium corporations and property managers can take to safeguard these hidden systems.

1. What Are Riser Expansion and Support Systems?

As water or heating fluids move through riser pipes, their temperature fluctuates significantly. This is most apparent in two-pipe fan coil systems, where supply temperatures during the summer months range from 40°F to 45°F, and during winter, they range from 160°F to 180°F, resulting in a temperature variance as large as 140°F in some systems. When fluid temperatures rise, the piping material expands; when temperatures drop, the material contracts. This expansion and contraction may seem minor, but over the height of a 30- or 40-storey building, these small movements accumulate into several inches of linear displacement.

To accommodate this movement and prevent stress on the piping system, engineers incorporate riser expansion and support systems, which are comprised of the following core components:

• Expansion Joints or Loops: Flexible sections of pipe or mechanical joints that absorb expansion movement. •
• Guides: Components that allow controlled movement in a longitudinal direction (along the riser length) but restrict lateral movement. These components are critical in ensuring the riser expands and contracts unidirectionally.
• Anchors: Anchors hold the pipe firmly in place to prevent uncontrolled displacement. These components ensure that the expansion and contraction of piping remain controlled and support the pipe’s vertical load.
• Flexible Couplings: May be required in retrofit applications to absorb small displacements in risers.

2. Importance of Riser Expansion & Support Systems

As the temperature of fluids within riser piping changes, the pipe material itself expands or contracts. This is particularly relevant in heating and cooling systems where temperature variances are substantial. For example:

• A steel riser spanning 30 floors can expand more than 2 inches with a 100°F temperature increase.
• A copper riser, which has a higher coefficient of thermal expansion than steel, can expand up to 3.2 inches over the same rise and temperature change.

When expansion is not properly accounted for, this movement places undue stress on joints, supports, and fittings, compromising the system’s structural integrity over time.

3. Consequences of Improperly Designed or Installed Systems

When expansion and support systems are poorly designed, incorrectly installed, or missing entirely, the following are the most common symptoms:

• Noise from Behind the Walls: lack of guides (common occurrence in buildings) results in lateral movement, damaging the internal components of expansion compensators, resulting in noise.
• Pipe Joint Failure: Due to excessive axial stress, soldered, brazed or threaded connections within the riser system can fail.
• Anchor Pull-out or Deformation: Compromised anchor points can lead to the riser falling, resulting in branch pipes coming into contact with fan coil or heat pump cabinets. In extreme cases, the pipe damage can lead to water leaks.
• Bent Riser Pipes: Undersized expansion loops or compensators result in thrust forces being transferred to anchor points which aren’t designed to accommodate these high loads. This results in the pipe bowing or buckling as it cannot move freely.

Figure 1: Compromised anchor point, resulting in the riser dropping.

Figure 2: Riser dropped, resulting in the branch line coming in contact with the fan coil unit cabinet and bending.

Figure 3: Bent riser pipe due to buckling.

Figure 4: Branch line in contact with the side of the cabinet due to excessive lateral movement.

4. Common Retrofit Challenges in Condominium Buildings

Retrofitting riser expansion and support systems in existing high-rise condominium buildings often comes with its own unique challenges. Unlike new construction, where riser pipes are completely exposed and expansion and support system provisions can be designed and coordinated, retrofit projects need to navigate around physical limitations, existing inefficiencies and accessibility issues arising from the existing structure. Below are some of the common challenges experienced:

Physical Limitations:

• Risers are typically located in narrow pipe shafts behind existing walls within residential units.
• Clearances between pipe shafts and the existing unit cabinets and drywall are tight, requiring innovative strategies to install new anchors and guide supports.

Accessibility & Scheduling Disruptions:

• Access to the riser piping requires suite entry and the demolition of existing walls.
• Coordinating entry with numerous residents can delay timelines and limit working hours if not carefully planned.
• Noise and periodic heating/cooling disruptions must be managed and communicated to residents well in advance.

Structural Constraints:

• Surrounding concrete slabs and walls restrict the placement of new equipment, requiring engineers and manufacturers to modify designs.
• Limited structural slab availability may cause challenges when installing anchors, as anchors are required to be supported by structural elements to withstand the riser loads.

5. Recommended Best Steps

Similar to other mechanical components and equipment within buildings, riser expansion and support systems require both proactive measures to ensure longevity and reactive intervention to tackle failures.

Proactive Measures:

• Review of Riser Expansion and Support systems during 1st year and 2nd year Performance Audits: This practice may be costly and cause disruption of newly built suites, but catching deficiencies at this time could result in invaluable long-term benefits for the corporation by having the builder remediate any defects during the warranty period.
• Accurate As-built Drawings: Working with the developer during the 1st year and 2nd year performance audit reviews to create accurate as-built drawings showing the correct location of the riser expansion and support systems would save considerable time and costs in the future when replacement is required.
• Routine Riser Audits: Corporations should conduct riser expansion and support system audits every 3 – 5 years to identify signs of riser movement and bowing to prevent catastrophic failures.
• Fan Coil / Heat Pump Maintenance Reviews: One of the simplest ways to monitor riser movement is when completing Fan Coil and/or Heat Pump Unit maintenance in suites. Observing the positioning of the branch lines can provide critical insight into the condition of the riser expansion and support system.

Reactive Intervention:

• Avoid Re&Re Replacements: I commonly hear that a failed expansion joint was replaced with another similar type. If the root cause of the failure is not addressed, the newly installed expansion joint will fail again within a couple of years.
• Engage Professional Engineers: Riser expansion and support systems should be designed to ensure correct load requirements, thermal expansion allowances and existing piping layouts.
• Phased Remediation: Corporations may opt to phase remediations due to budgetary constraints and manage disruption to residents. Trained professionals can help guide and provide a phasing methodology and strategy.

Though hidden behind walls, riser expansion and support systems are essential to the safe and efficient operation of high-rise condominiums. When properly designed and maintained, they accommodate thermal movement, prevent structural stress, and reduce the risk of pipe failure and water damage. When overlooked, however, they can lead to costly repairs, resident disruption, and long-term asset deterioration.

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Kaezad Wania, P.Eng is the Vice President of Engineering & Operations at Baypath Inc. With over nine years of experience in building systems engineering, Kaezad has managed and supported numerous condominium corporations through a wide range of projects, including equipment & system retrofits, building audits, technical investigations, and energy efficiency upgrades.