How to Build a Chase: A Complete Guide for Construction and HVAC Projects
In modern construction, concealing mechanical systems like plumbing, electrical wiring, HVAC ducts, and flue pipes is essential for both functionality and aesthetics. One of the most effective solutions for this is to build a chase—an enclosed space designed to house these systems without interfering with the structural integrity or visual appeal of a building.
Whether you’re constructing a new home, remodeling, or managing a commercial project, knowing how to properly build a chase can make a significant difference in efficiency, safety, and serviceability. This comprehensive guide will walk you through the definition, types, construction methods, materials, safety codes, and best practices involved in building a chase.
What Is a Chase in Construction?
A chase (also called a “utility chase”) is a framed and enclosed pathway—usually vertical or horizontal—constructed to conceal building systems such as:
- Plumbing pipes
- Electrical conduits
- HVAC ducts
- Flue or vent pipes
- Communication wiring
Unlike wall chases that are cut into existing walls, a built chase is a deliberately framed cavity, often made from wood or metal studs and finished with drywall or sheathing. It can be designed into the building from the start or added later as part of a retrofit.
Why Build a Chase?
Building a chase offers several practical and regulatory benefits:
✅ Aesthetics
Hides unsightly ducts, pipes, and wiring behind finished surfaces.
✅ Safety
Protects occupants from exposed wiring or hot flue pipes, and contains firestopping materials where needed.
✅ Access
Allows maintenance access via panels without disturbing finishes.
✅ Organization
Provides a centralized route for mechanical systems in multi-story or complex floor plans.
✅ Compliance
Ensures routing of services complies with building, plumbing, mechanical, and fire codes.
Where Are Chases Typically Built?
| Location | Purpose |
|---|---|
| Bathrooms | To conceal plumbing for sinks, toilets, and showers |
| Kitchens | For gas pipes, water lines, or vent hoods |
| Utility rooms | To house flue pipes, water heaters, and HVAC ducts |
| Basements | Conceal trunk ducts or vertical risers to upper floors |
| Attics | Enclose refrigerant lines and return air ducts |
| Living spaces | Hide entertainment wiring or data cabling |
Types of Chases You Can Build
1. Vertical Chase
A chase that runs upward between floors, usually to carry HVAC ducts, plumbing stacks, or flue pipes.
2. Horizontal Chase
A framed enclosure along ceilings or walls used to conceal wiring or horizontal ductwork.
3. Soffit Chase
A chase built into a ceiling drop-down (soffit), often used in basements or hallways.
4. Shaft Chase
A more robust, often fire-rated chase used in commercial or multi-family buildings to house major utility risers.
Materials Required to Build a Chase
| Component | Recommended Material |
|---|---|
| Framing | 2×4 or 2×6 wood studs, or light-gauge metal studs |
| Fasteners | Wood screws, framing nails, or drywall screws |
| Sheathing | Standard or Type X drywall (for fire-rated applications) |
| Insulation | Fiberglass batts or rigid foam for thermal/sound insulation |
| Firestop sealant | Intumescent caulking, collars, or wrap strips |
| Access panels | Removable or hinged panels for servicing concealed elements |
Step-by-Step Guide: How to Build a Chase
Step 1: Planning the Layout
- Identify the mechanical systems that need concealment
- Measure space requirements, considering future access
- Determine the location of any fire-rated walls or floors
Step 2: Frame the Structure
- Mark the perimeter of the chase on walls, ceilings, or floors
- Frame the structure using wood or metal studs, maintaining spacing (typically 16″ on center)
- If enclosing a vertical chase, ensure framing is continuous and securely fastened
Step 3: Route the Services
- Install HVAC ducts, plumbing, or wiring inside the chase
- Use hangers and supports to prevent sagging or contact with the chase walls
- Follow clearance guidelines for gas pipes and electrical wiring
Step 4: Install Firestopping (If Required)
- Apply firestop sealant around any penetrations in fire-rated assemblies
- Use Type X drywall or UL-listed shaft liner where needed
Step 5: Insulate and Sheathe the Chase
- Add insulation if required for soundproofing or thermal control
- Attach drywall or sheathing to the chase frame
- Finish with joint compound and paint as needed
Step 6: Add Access Panels
- Install removable panels at key junctions or valves
- Clearly label access points for maintenance purposes
Code Compliance and Safety Tips
🔹 Fire Rating
If your chase goes through multiple floors or fire-rated assemblies, it must be constructed with fire-resistant materials and include appropriate firestopping.
🔹 Separation of Systems
Don’t run water and electrical together without physical separation. This reduces the risk of shorts, corrosion, and code violations.
🔹 Ventilation
If your chase encloses combustion appliances or flue pipes, ensure adequate ventilation to prevent carbon monoxide buildup.
🔹 Accessibility
Install access panels where needed to allow servicing without wall demolition.
Chase vs. Wall Chase: What’s the Difference?
| Chase | Wall Chase |
|---|---|
| A framed cavity built from scratch | A groove cut into an existing solid wall |
| Used in new construction or remodeling | Used in retrofits or electrical installations |
| Accommodates larger systems | Limited to small wiring or pipes |
| Less invasive, easier to inspect | Can weaken structural masonry if overdone |
Best Practices When Building a Chase
- Overestimate the space needed—future systems may need more room
- Label what’s inside the chase before sheathing for future reference
- Avoid sharp bends in ducting or piping for better performance
- Seal and insulate ducts before enclosing
- Coordinate with all trades—HVAC, plumbing, electrical—to avoid conflicts
Common Mistakes to Avoid
| Mistake | Impact |
|---|---|
| Chase too small | Difficult installation and future upgrades |
| No access panel | Costly and destructive maintenance work |
| Ignoring fire codes | Code violations and increased fire risk |
| Combining incompatible systems | Can cause damage, safety hazards, or inefficiency |
| Poor sealing or insulation | Leads to air leaks, heat loss, or condensation |
Applications in Residential vs. Commercial Buildings
| Aspect | Residential | Commercial |
|---|---|---|
| Size | Smaller, often in bathrooms or kitchens | Larger, often multi-floor utility shafts |
| Fire requirements | May not require fire rating in single-family | Often includes 1-hour or 2-hour rated assemblies |
| Complexity | Simple runs (1–2 systems) | Integrates HVAC, electrical, comms, and plumbing |
| Materials | Wood framing, standard drywall | Metal studs, shaftliner, fire-rated drywall |
Conclusion
Knowing how to build a chase is an invaluable skill for any builder, contractor, or homeowner involved in construction or renovation projects. A properly designed chase not only hides necessary mechanical systems but also improves safety, aesthetics, and future serviceability. From planning and framing to insulation and fire safety, every step must be carried out with precision and compliance to building codes.
By understanding the structure, materials, and techniques involved, you can ensure that your chase adds long-term value and efficiency to any property.
FAQs About Building a Chase
Q1: Can I build a chase in an existing home?
Yes, though it requires cutting drywall and framing a cavity or soffit. It’s easier during full remodels or when updating HVAC/plumbing systems.
Q2: Do I need a permit to build a chase?
If it affects load-bearing walls, includes fire-rated assemblies, or involves electrical/plumbing work, permits and inspections are likely required. Always check with your local building authority.
Q3: How deep should a chase be?
It depends on the systems being concealed. For small wiring, 4″ may suffice. For HVAC ducts or multiple pipes, 12–24″ may be needed.
Q4: Is it okay to run multiple systems in one chase?
Only if allowed by code and proper separation, insulation, and firestopping are maintained between systems (e.g., electrical and gas pipes).
Q5: Can I use wall cavities as chases?
Not recommended for return air ducts or major systems. Dedicated, framed chases are more compliant and accessible.
Q6: How do I insulate a chase?
Use foil-faced fiberglass or rigid foam around ducts/pipes, and batts or foam board within the chase if it’s in unconditioned space.
Q7: What’s the difference between a shaft and a chase?
A shaft is typically a fire-rated vertical space used in commercial/multi-family buildings for risers, while a chase is any framed space for utility runs in both residential and commercial construction.
Q8: Can I access the systems inside the chase later?
Yes—if you install access panels at valves, dampers, or junction points. Otherwise, you’ll have to cut into the wall or ceiling.
With the right planning, materials, and execution, building a chase can significantly enhance the durability, safety, and finish quality of any construction project.
