Upgrading an existing building often means working around hydraulic services that were designed for a completely different layout, use or level of demand.
In a new building, hydraulic services can generally be designed around the proposed architecture and coordinated before construction begins.
A refurbishment project is different.
Existing water, sanitary, drainage and stormwater services may already be embedded within the building structure. Pipework may be concealed above ceilings, below floors or behind walls. Original documentation may be incomplete, and previous alterations may have changed the way services are arranged.
At the same time, the refurbishment may introduce new bathrooms, kitchens, amenities, equipment or occupancies that place different demands on the existing hydraulic infrastructure.
As a result, what appears to be a relatively straightforward refurbishment can become significantly more complex once the existing services are investigated.
Existing Hydraulic Services May Not Match the Proposed Design
One of the first challenges in a refurbishment project is understanding what already exists.
The proposed architectural layout may include new bathrooms, kitchens, tea points, laundries or other areas requiring water supply and drainage connections. However, the location of existing hydraulic services may not align with the new design.
A new fixture cannot simply be positioned wherever the layout requires if suitable water supply, drainage or sanitary connections are not available.
For example, relocating a bathroom may require consideration of:
- Existing drainage connection points
- Available pipe grades and falls
- Pipe sizes and capacity
- The location of vertical risers
- Structural elements
- Available ceiling or floor space
- Connections to existing sanitary or sewer systems
The further the proposed layout moves away from the original service locations, the more extensive the hydraulic alterations may become.
Drainage Is Not Always Easy to Relocate
Water supply pipework can often be routed around an existing building with some flexibility.
Drainage is different.
Gravity drainage relies on appropriate pipe grades and falls. In an existing building, achieving those requirements can be difficult when floor levels, structural beams, ceiling heights and existing services limit where new pipework can be installed.
A proposed fixture location may look straightforward on an architectural plan but become difficult once the required drainage route is considered.
The challenge can increase when:
- New fixtures are located away from existing drainage points
- Floor levels cannot be altered
- Structural elements restrict pipe routes
- Ceiling space is limited
- Multiple services need to share the same service zone
In some situations, a small change to the architectural layout can significantly simplify the hydraulic design.
This is why hydraulic coordination should not be left until after key layout decisions have already been made.
Existing Pipework May Be Difficult to Access
Much of the hydraulic infrastructure in an existing building is concealed.
Pipework may be located within walls, above ceilings, below floors or inside building risers. Accessing these services may require opening finishes or investigating areas that are not visible during the early stages of design.
This creates uncertainty.
The original drawings may indicate one arrangement, but previous renovations or undocumented alterations may mean the actual installation is different.
Before major refurbishment work proceeds, it may be necessary to investigate:
- The location of existing pipework
- Pipe sizes and materials
- The condition of existing services
- Available connection points
- Whether previous alterations have affected the system
- Potential clashes with structural or other building services
Without a clear understanding of the existing conditions, the hydraulic design may be based on assumptions that later need to be revised.
New Uses Can Place Different Demands on Existing Services
A refurbishment may also change how a building or particular area is used.
For example, an existing commercial space may be converted into a medical facility, hospitality venue, workplace or another type of occupancy with different hydraulic requirements.
Even changes that appear relatively minor can affect the existing infrastructure.
Additional fixtures, increased occupancy or new equipment may place greater demand on:
- Water supply systems
- Hot water systems
- Sanitary drainage
- Trade waste infrastructure
- Stormwater systems
The existing services may have been adequate for the original use of the building but may not be suitable for the proposed refurbishment.
Understanding these changes early allows the design team to assess whether the existing infrastructure can support the new requirements or whether upgrades will be needed.
Coordination With Other Services Can Become Congested
Hydraulic services rarely exist in isolation.
In refurbishment projects, new and existing hydraulic pipework may need to share limited space with mechanical, electrical, fire and structural elements.
Ceiling spaces can quickly become congested.
A proposed hydraulic route may conflict with ductwork. A drainage pipe may require space that is already occupied by structural elements. Access requirements for valves, pumps or equipment may also need to be considered.
These issues are particularly common in projects where the available service space was designed around the original building configuration rather than the new layout.
Without early coordination, clashes can emerge during construction when services are being installed and changes become more disruptive and expensive.
Fire and Acoustic Requirements Can Affect Service Routes
Refurbishment work can also involve changes to fire or acoustic requirements.
Where hydraulic services pass through walls or floors, the design may need to consider how penetrations are managed and how the relevant performance requirements are maintained.
This can affect:
- Where pipework can be routed
- The size and location of penetrations
- Available service zones
- Access for installation and maintenance
- Coordination with architectural and fire services requirements
These considerations are easier to address during design than after pipework routes have already been established on site.
Stormwater Can Also Be Affected by Building Changes
Hydraulic refurbishment work is not limited to internal water and drainage services.
Changes to a building can also affect stormwater management.
Extensions, roof alterations, new external works or changes to site levels can alter how stormwater is collected and discharged.
Existing stormwater infrastructure may need to accommodate new roof areas or changes to surface drainage.
Depending on the project, this may involve reviewing:
- Existing stormwater connection points
- Drainage capacity
- New roof drainage requirements
- Site levels and surface runoff
- The impact of new building works on existing drainage paths
Stormwater requirements should be considered as part of the overall refurbishment design rather than treated as a separate issue once other decisions have already been made.
Why Early Investigation Makes a Difference
Many hydraulic problems in refurbishment projects are not caused by poor design.
They arise because the design process begins without enough information about the existing building.
Early investigation can help identify:
- Existing service locations
- Potential connection points
- Pipe sizes and capacity
- Constraints created by the structure
- Areas where services are congested
- Potential upgrades required for the proposed use
This information gives the design team a stronger basis for making decisions before the project reaches construction.
It can also reveal when an apparently simple design change may have significant implications for the hydraulic system.
Hydraulic Design Is About More Than Connecting New Fixtures
In a refurbishment project, hydraulic design is not simply a matter of connecting new fixtures to the nearest available pipe.
The design needs to consider how new and existing services will work together within the constraints of the building.
That can involve balancing:
- Architectural requirements
- Existing building conditions
- Drainage requirements
- Water demand
- Available service space
- Structural constraints
- Coordination with other building services
- Construction practicality
The earlier these factors are considered together, the greater the opportunity to resolve issues before they affect the construction program.
Engineering Support for Building Refurbishment Projects
Building refurbishments can involve significant uncertainty, particularly when existing hydraulic infrastructure needs to support a new layout or use.
Understanding the existing conditions and coordinating hydraulic requirements with the wider building design can help identify potential constraints before they become on-site problems.
Decobu provides building services engineering and design support across hydraulic, mechanical, electrical and fire services. For refurbishment projects, this can involve investigating existing conditions, assessing proposed changes and coordinating services within the constraints of the existing building.
The objective is not simply to design new services, but to develop a coordinated approach that considers how those services can work within the building that already exists.
Frequently Asked Questions
Why are hydraulic services more difficult to modify in an existing building?
Existing pipework may be concealed within walls, floors and ceilings, while structural elements and limited service space can restrict where new services can be installed. The existing infrastructure may also not align with the proposed building layout.
Can existing drainage always support new bathrooms or kitchens?
Not necessarily. The location, capacity and configuration of the existing drainage system need to be considered. New fixtures may require additional pipework or changes to the existing infrastructure.
Why is drainage harder to relocate than water supply pipework?
Drainage systems generally rely on gravity, which means pipework needs appropriate grades and falls. Existing floor levels, structural elements and limited ceiling space can restrict the available routes.
What should be investigated before designing new hydraulic services?
It is useful to understand the location, condition and capacity of existing services, along with available connection points, structural constraints and the proposed changes to the building.
When should hydraulic services be considered during a refurbishment?
Hydraulic services should be considered early enough for the existing infrastructure and service requirements to influence the proposed layout before key design decisions are locked in.
Final Thoughts
Hydraulic services can become one of the more complex parts of a building refurbishment because new requirements need to work within the constraints of an existing structure and infrastructure.
Hidden pipework, drainage limitations, changes in building use, limited service space and coordination with other disciplines can all affect what is practical.
By investigating existing conditions and considering hydraulic requirements early, potential constraints can be identified before they become more difficult to resolve during construction.
Contact Decobu for building refurbishment projects requiring coordinated building services engineering, we provide support across hydraulic, mechanical, electrical and fire services.