- A tenant improvement changes how a space is used, and HVAC usually has to change with it: new walls, new loads, new ventilation needs, and often new zoning.
- Begin by reading the lease and the landlord's building standards; they determine who owns existing equipment, who must approve changes, and which contractors may work on base-building systems.
- Do not assume the existing equipment can handle the new layout. A load check early in design prevents expensive change orders after framing.
- HVAC has fixed points in the construction schedule (rough-in before ceilings, start-up before final inspection, balancing before occupancy), and delays upstream compress them.
- Closeout paperwork (as-builts, test reports, warranties, O&M information) is part of the deliverable, not an afterthought.
What a tenant improvement means for HVAC
A tenant improvement (TI) is a buildout or renovation of leased commercial space: a restaurant fitting out a shell, a clinic converting an office suite, a retailer reconfiguring a storefront, a company reorganizing a floor. The HVAC scope can be small (relocating a few diffusers) or large (new rooftop units, new ductwork, and a new control strategy), and it is rarely zero.
The reason is simple. Walls move, so airflow paths change. Occupancy and equipment loads change, so cooling and heating needs change. Use changes, so ventilation requirements change. A conference-heavy office that becomes an open plan, or a retail shop that becomes a salon, has a different air balance from what was originally built.
Start with the lease and the landlord's rules
Before anyone designs anything, find out who owns what. In many leases, rooftop units serving a tenant suite are either landlord-owned base-building equipment or tenant-owned equipment that the tenant must maintain. Alterations to either may need written landlord approval, and some landlords require that work be done by approved contractors or according to their building standards.
| Question | Why it matters |
|---|---|
| Who owns and maintains the existing HVAC serving the space? | Determines who pays for modifications and who carries warranty and maintenance duties |
| Is there an approved contractor list or building standard? | Some work must be done by designated firms to protect base-building systems |
| What are the rules for roof access, penetrations, and crane use? | Roof warranties and structural limits can govern equipment placement |
| What are the after-hours and noise limits? | Occupied buildings restrict noisy and disruptive work |
| Are there shutdown notice requirements? | Water, power, and HVAC interruptions often require advance notice |
| Does the landlord require plan review and approval? | Drawings may need approval before permit submittal |
| What insurance and bonding documentation is required? | Missing certificates can stop work on the day it starts |
Load changes and design
Existing equipment was sized for a previous layout. The new design should be checked against it before walls are framed. Items that commonly change the load:
- Higher occupant density from meeting areas, training rooms, or open seating.
- More equipment heat such as server closets, kitchens, imaging equipment, or production tools.
- New or larger glazing and changes to lighting.
- Dedicated ventilation needs for restaurants, salons, medical suites, and similar uses, often involving exhaust and make-up air. See kitchen ventilation and make-up air.
- Separate zoning needs, like a private office that requires different temperature control from the open area.
- After-hours loads, such as a server room that needs cooling when the rest of the suite does not.
The design may be produced by a mechanical engineer, by the design-build contractor, or by a combination, depending on the project and local requirements. Either way, bring the HVAC contractor into the process early. A short walkthrough before the drawings freeze often reveals ceiling clearance problems, duct routes blocked by structure, or undersized equipment while they are cheap to fix. Our commercial HVAC project delivery and bidding guide explains how scope is typically divided.
Options include adding a supplemental split or VRF system for the changed area, replacing the rooftop unit, or adding zone dampers and controls. Each has implications for landlord approval, roof capacity, and code. See RTU and split system installs and VRF and split systems.
Permits and code
Most TI projects with mechanical changes need a building permit, and the energy code (Title 24, Part 6) generally applies to the altered scope. That can include requirements for equipment efficiency, controls, ventilation, and documentation, and may involve acceptance testing for certain systems. Requirements vary by jurisdiction and change with code cycles, so confirm them with the local building department for the project address.
- Decide who pulls the mechanical permit (the GC, the HVAC contractor, or the owner's representative), and make sure the scope is covered by a licensed contractor.
- Confirm whether energy-code compliance forms must be submitted with the application or at final.
- Schedule required inspections early; rough-in must typically pass before ceilings close.
- Track fire and life-safety interfaces such as smoke dampers, duct detectors, and shutdown interlocks, which are coordinated with other trades.
Our Title 24, permits, and HVAC replacement guide goes further on this topic, and the energy efficiency and incentives guide covers broader context.
Sequencing with the general contractor
HVAC work lives inside the GC's schedule, and some points are not negotiable. The sequence below is typical but should be adapted to each project.
- Preconstruction: Review drawings, confirm equipment lead times, identify long-lead items, and flag conflicts with structure, plumbing, and lighting.
- Demolition: Disconnect and cap existing ducts and controls; protect equipment that stays.
- Roof or equipment set: Schedule crane or rigging with the landlord, and coordinate roofing repairs for any penetrations.
- Rough-in: Install ductwork, hangers, refrigerant lines, condensate piping, and control wiring before ceilings and walls close. Inspect before covering.
- Trim and devices: Install diffusers, grilles, thermostats, and sensors after ceilings and finishes.
- Start-up: Energize equipment, verify refrigerant, electrical, airflow, and controls.
- Testing and balancing: Adjust airflow to design values and document results.
- Final inspection and punch list: Close out remaining items and deliver documents.
Common friction points include ceiling grid installed before ductwork is inspected, electrical service not available for start-up on time, and late equipment deliveries. Raise lead-time concerns at kickoff, not at rough-in.
Balancing, testing, and acceptance
Air balancing measures and adjusts supply, return, and outside airflow so each space gets what the design intended. It is easy to skip on small jobs and it is the step most often responsible for hot and cold complaints afterward. For projects where it is required or specified, a qualified balancing firm should verify airflows and report results.
- Verify the minimum outside air is delivered, since it is both a code and comfort issue.
- Confirm that exhaust and make-up air are in balance in kitchens and similar spaces; a negative building pressure causes door and comfort problems.
- Check thermostat or sensor placement and calibration; poor placement creates complaints that no amount of balancing can fix.
- Record final damper positions and settings.
- Where code requires acceptance testing, schedule it before the final inspection.
Closeout and handoff
A TI is not finished at occupancy. The tenant, and often the landlord, need documents that let them run and maintain the system.
| Closeout item | Purpose |
|---|---|
| As-built drawings of ductwork, equipment, and controls | Future service, additions, and landlord records |
| Start-up and test reports | Evidence of proper commissioning |
| Balancing report | Reference for troubleshooting airflow complaints |
| Equipment data, model and serial numbers, warranty terms | Warranty claims and replacement planning |
| Controls sequences, schedules, and passwords | Operation and troubleshooting without guesswork |
| Permit sign-offs and energy-code documentation | Compliance record |
| Maintenance recommendations | Prevents early failures that void warranties |
Each new unit can be entered into the DaVinci Portal at closeout so its service history begins on day one, with a maintenance plan set up before the first season rather than after the first failure.
Bidding and selecting an HVAC contractor for a TI
Compare bids on scope, not just on total. Check what each includes: equipment, curbs, rigging, controls, permits, balancing, and closeout documents. Ask about schedule commitments and who coordinates with the landlord. Davinci Mechanical is a commercial-only contractor licensed in California (CA #1083101), working on bid projects, and prevailing-wage and union work where required. See bid projects and our guide to choosing a commercial HVAC contractor.
Frequently asked questions
Does a tenant improvement always require new HVAC equipment?
No. Many TIs adjust ductwork, diffusers, and controls using existing equipment. A load check will show whether the equipment can carry the new layout.
Who approves HVAC changes in a leased space?
Usually the landlord or property manager, according to the lease. They may also set rules about contractors, roof access, and drawings. Check the lease and building standards early.
Why is air balancing necessary?
It confirms that each area gets the airflow the design intended, including outdoor air. Skipping it is a common cause of hot and cold spots and ventilation shortfalls.
What causes HVAC to delay a TI schedule?
Long equipment lead times, delayed landlord approvals, late electrical service, and rough-in inspections that are not scheduled in time. Identifying them at kickoff helps.
When should the HVAC contractor be brought in?
As early as possible, ideally before drawings are finalized. Early input on equipment, ceiling space, and routing reduces change orders later.
Have a site this applies to?
Davinci Mechanical is the commercial and union division of Scottish Tom's Heating & Air. Send us the equipment list or the problem and we'll tell you what we'd check first.