Short answer: HVAC planning for new construction in Las Vegas should begin during the design development phase — at least 60-90 days before the building permit application. The HVAC rough-in typically occurs after framing and before insulation and drywall, requiring coordination with electrical, plumbing, and fire protection trades. In Las Vegas, the full HVAC timeline from initial load calculation through final commissioning spans 4-8 months depending on project size, with Clark County permit review adding 3-6 weeks. The two most common schedule busters are late HVAC design changes that conflict with structural members, and equipment lead times on higher-efficiency or commercial-grade units that can run 6-12 weeks.
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Why HVAC Is the Trade That Cannot Be an Afterthought
In new construction, HVAC ductwork, refrigerant lines, and equipment pads compete for the same physical space as structural members, plumbing drains, electrical conduit, and fire sprinkler piping. The HVAC system is typically the most space-consuming mechanical system in a building — ductwork alone can require 6-14 inches of vertical clearance, and trunk lines in commercial builds can be 24 inches or more.
When HVAC design is finalized late, everything conflicts. A supply trunk that was designed to run through a corridor ceiling discovers a 12-inch steel beam in its path. A return air chase conflicts with a plumbing stack. A rooftop unit pad was not coordinated with the structural engineer, and the roof framing cannot support the weight.
These conflicts do not just add cost. They add weeks. In Las Vegas, where construction schedules are compressed by the extreme heat window — you do not want framers, roofers, or HVAC rough-in crews working through July and August if it can be avoided — schedule delays cascade through every downstream trade.
This timeline is built for Las Vegas general contractors, builders, and project managers who coordinate multi-trade schedules and need to know when the HVAC contractor needs to be engaged, what decisions must be made at each phase, and where the common schedule traps are.
Phase 1: Pre-Design and Concept (Before Architecture Begins)
When: Before or concurrent with architectural schematic design
HVAC contractor involvement: Consultation only
Most builders do not engage an HVAC contractor until design development. That is acceptable for production homes with standard floor plans. For custom homes, commercial buildings, or any project with non-standard requirements, early HVAC consultation prevents costly redesign.
What to Establish in Pre-Design
Building use and occupancy. A medical office has fundamentally different ventilation requirements than a retail store. A restaurant requires kitchen ventilation that drives significant mechanical space requirements. Defining the use early prevents the architect from designing spaces that cannot accommodate the required HVAC systems.
Comfort and performance targets. Will the building use standard comfort cooling (maintain 75-78 degrees F during Las Vegas peak conditions) or does it need tight temperature control (server rooms, wine storage, medical imaging)? Standard comfort cooling sizes at approximately 400-500 square feet per ton in Las Vegas. Tight temperature control may require 200-300 square feet per ton and dedicated systems.
Energy code path. Clark County enforces the International Energy Conservation Code (IECC). Compliance path — prescriptive or performance — affects equipment efficiency requirements, duct insulation values, and envelope specifications. Deciding the compliance path early prevents late-stage equipment substitutions.
Budget range for HVAC. For new construction in Las Vegas, budget ranges are approximately:
- Production residential: $3,000-$6,000 per ton installed (including ductwork, controls, and permits)
- Custom residential: $5,000-$10,000 per ton installed
- Commercial (packaged rooftop units): $2,500-$5,000 per ton installed
- Commercial (central plant or VRF): $4,000-$8,000 per ton installed
Establishing a budget range in pre-design prevents designing a building that requires $120,000 in HVAC when the budget allows $60,000.
Phase 2: Design Development (Architecture 50-75% Complete)
When: 90-120 days before building permit application
HVAC contractor involvement: Active design and coordination
This is the critical phase for HVAC. The HVAC mechanical design must be developed concurrently with architectural design development, not after the architecture is finalized.
Manual J Load Calculation (Residential) or Commercial Load Analysis
For residential projects: A Manual J load calculation sizes the HVAC system based on the actual building envelope — wall insulation, window specifications, roof insulation, orientation, and shading. In Las Vegas, the cooling design temperature is 111 degrees F (ASHRAE 0.4% design), and solar heat gain through west-facing windows is the single largest cooling load component in most homes.
For commercial projects: A commercial load analysis (often using Trane TRACE, Carrier HAP, or similar software) models the building's thermal performance hour by hour across a design year. This analysis determines not just total tonnage but peak load timing, which affects equipment selection and utility demand charges.
Las Vegas load calculation factors that are commonly underestimated:
- West-facing glazing. A wall of west-facing windows in Las Vegas can add 2-3 tons of cooling load that does not exist on the north side of the same building. Proper load calculations account for orientation; rules of thumb do not.
- Attic temperatures. Attic temperatures in Las Vegas reach 150-160 degrees F during peak summer. Ductwork in the attic loses significant cooling capacity unless it is properly insulated (R-8 minimum, R-12 recommended for Las Vegas) and sealed.
- Infiltration. New construction in Las Vegas is typically tight (2-4 ACH50 for code-compliant homes), but envelope air sealing must be verified before final HVAC sizing is confirmed.
Equipment Selection and Lead Times
Once the load calculation is complete, equipment selection begins. This is where lead times become a schedule factor.
Standard efficiency equipment (14-16 SEER2): Typically available from local distributors within 1-2 weeks. Production builders with established supply relationships often keep standard models in stock.
High-efficiency equipment (18+ SEER2, variable speed, or VRF): Lead times of 4-8 weeks are common. During peak construction seasons (spring and fall in Las Vegas), lead times can extend to 12 weeks for specific models and configurations.
Commercial equipment (packaged rooftop units 7.5+ tons): Lead times of 6-12 weeks depending on manufacturer, tonnage, and options. Custom configurations (specific economizer options, gas/electric combinations, high-static fan packages) add 2-4 weeks.
Order equipment as soon as the load calculation and design are approved. Do not wait for the building permit — you can order equipment based on approved mechanical design while the permit is in review.
Duct Layout and Routing
The mechanical designer or HVAC contractor produces a duct layout showing supply and return trunk lines, branch ducts, register locations, and equipment placement. This layout must be coordinated with:
- Structural: Beams, headers, trusses, and bearing walls determine where ducts can and cannot run. A 14-inch round supply duct cannot pass through a 12-inch truss without a structural modification.
- Plumbing: Drain lines have mandatory slopes and limited routing flexibility. HVAC ducts must route around plumbing rather than competing for the same joist bays.
- Electrical: Main electrical panels, sub-panels, and conduit runs must not conflict with duct routes or equipment locations.
- Fire protection: Sprinkler main runs and branch lines occupy ceiling space and must be coordinated with duct routing.
In Las Vegas custom homes and commercial projects, a coordination meeting between all trades before design is finalized prevents the majority of field conflicts. This meeting costs nothing and saves thousands.
Phase 3: Permitting (3-6 Weeks)
When: After design development is complete
HVAC contractor involvement: Permit application support
Clark County Permit Timeline
Clark County Building Department mechanical permit review typically takes:
- Residential (production plans): 2-3 weeks if the plan reviewer has no comments
- Residential (custom): 3-4 weeks, often with one round of corrections
- Commercial: 4-6 weeks, frequently with corrections requiring resubmission
Parallel permitting: Mechanical permits can be submitted simultaneously with building, plumbing, and electrical permits. They do not need to be sequential. However, the building permit must be issued before rough-in work can begin.
What the Plan Reviewer Checks
- Equipment sizing relative to load calculation
- Duct sizing for proper airflow distribution
- Return air pathway adequacy (every supply CFM needs a return path)
- Energy code compliance (equipment efficiency, duct insulation, duct sealing)
- Equipment location clearances (service access, combustion air for gas equipment)
- Outdoor equipment placement (setbacks, noise, and clearances)
Common Permit Correction Items in Clark County
- Missing Manual J or load calculation documentation. Clark County requires a load calculation for all HVAC permits. A contractor who sizes by rule of thumb will not pass plan review.
- Duct insulation not specified. All supply ductwork in unconditioned spaces (attics, garages) must be insulated to R-8 minimum.
- Equipment efficiency below code minimum. As of January 2025, the minimum efficiency for residential split systems in Las Vegas is 15 SEER2 / 12.2 EER2 for cooling and 7.8 HSPF2 for heat pumps.
- Return air system inadequacy. Central returns without transfer paths from bedrooms create pressure imbalances. Clark County reviewers increasingly require dedicated return pathways or transfer grilles for each bedroom.
Phase 4: Rough-In (The Critical Window)
When: After framing inspection, before insulation
Duration: 3-7 days for residential, 2-6 weeks for commercial
HVAC contractor involvement: Full crew on-site
The HVAC rough-in is the most schedule-sensitive phase of the HVAC installation. It must occur in a specific sequence relative to other trades.
The Trade Sequence
- Framing complete and inspected — HVAC cannot begin rough-in until framing passes inspection
- Plumbing top-out — Drain lines and vent stacks are typically installed first because they have the least routing flexibility
- HVAC rough-in — Ductwork, refrigerant lines, condensate drains, control wiring, and gas piping for HVAC equipment
- Electrical rough-in — Can overlap with HVAC in most cases
- Fire sprinkler rough-in — Often last due to its dependence on ceiling cavity space
- Insulation — After all rough-in trades pass inspection
- Drywall — Covers all rough-in work
What Happens During HVAC Rough-In
Residential rough-in (3-7 days):
- Install supply and return trunk lines
- Run branch ducts to each register location
- Install register boots (the connection between ductwork and the ceiling or floor opening)
- Run refrigerant line sets from the indoor coil location to the outdoor unit pad
- Install condensate drain lines (primary and secondary/emergency)
- Run thermostat and control wiring
- Install gas piping to the furnace location (if gas heating)
- Set the air handler or furnace in its designated location
- Install any required fire dampers at rated wall penetrations
Commercial rough-in (2-6 weeks):
All of the above, plus:
- Main duct trunk fabrication and installation (often custom-fabricated sheet metal)
- VAV box installation and connection
- Roof curb and structural support installation for rooftop equipment
- Building automation system wiring
- Exhaust system ductwork (kitchen, bathroom, parking garage)
- Make-up air system ductwork
Las Vegas Rough-In Considerations
Attic work during summer. If the rough-in schedule places HVAC crews in the attic during June through September, expect productivity to drop 30-50%. Las Vegas attic temperatures exceed 150 degrees F, and crews can only work 15-20 minutes at a time before requiring cooling breaks. This is not a scheduling preference — it is an OSHA heat illness prevention requirement. Plan rough-in for spring or fall whenever possible.
Roof penetrations. Every rooftop unit, exhaust fan, and vent pipe requires a roof penetration. In Las Vegas, where torrential monsoon rains can drop 1-2 inches in under an hour, proper flashing and sealing of roof penetrations is critical. Coordinate with the roofing contractor to ensure penetrations are properly integrated into the roofing system rather than cut and patched after the fact.
Condensate drain routing. In Las Vegas, air conditioning condensate is substantial — a 5-ton residential system can produce 5-10 gallons per day during peak summer. Primary condensate drains route to the plumbing system. Secondary (emergency) drains typically route to a visible location (above a window or at the eave) so that drainage from the secondary drain signals a primary drain failure.
Phase 5: Rough-In Inspection
When: Immediately after HVAC rough-in, before insulation
Duration: 1-2 days for scheduling, 1-2 hours for the actual inspection
Clark County inspectors verify:
- Ductwork is properly supported and connected
- Refrigerant line sets are properly insulated
- Condensate drains are properly sloped and connected
- Gas piping is properly sized and pressure-tested
- Fire dampers are installed at all rated penetrations
- Equipment location matches approved plans
- Duct sealing meets energy code requirements (mastic or UL 181-rated tape — cloth duct tape is not code-compliant)
Schedule impact of failed inspection: A failed rough-in inspection typically requires 1-3 days to correct and re-inspect. During peak construction season, re-inspection scheduling can add additional delays. The most common failure items are improper duct support (flex duct sagging between supports) and missing condensate drain traps.
Phase 6: Trim-Out and Equipment Setting
When: After drywall, painting, and flooring (or concurrent with finish trades)
Duration: 1-3 days residential, 1-3 weeks commercial
Residential Trim-Out
- Install registers and grilles
- Set the outdoor condenser unit on its pad
- Connect refrigerant lines between indoor and outdoor units
- Install thermostat
- Connect electrical service to equipment
- Charge the system with refrigerant (after pressure test and vacuum)
- Perform initial startup and test
Commercial Trim-Out
- Set rooftop units via crane onto roof curbs
- Make final duct connections to equipment
- Install thermostats and zone sensors
- Complete building automation system programming
- Charge systems and perform initial startup
- Begin commissioning sequence
Equipment setting coordination: Commercial rooftop units weighing 400-4,000+ pounds require crane access. The crane must be scheduled weeks in advance, and the site must have clear access for the crane to reach the roof. Coordinate with the general contractor to ensure the crane date does not conflict with concrete pours, steel deliveries, or other crane-dependent activities.
Phase 7: Commissioning and Final Inspection
When: After all mechanical, electrical, and controls work is complete
Duration: 1 day residential, 1-4 weeks commercial
Residential Commissioning
- Verify airflow at each register (every room receiving design CFM)
- Measure supply and return air temperatures (16-22 degree split across the coil)
- Verify refrigerant charge by subcooling and superheat method
- Test all operating modes (cooling, heating, fan-only)
- Program thermostat schedules
- Walk the homeowner through system operation
- Complete warranty registration
Commercial Commissioning
- Verify airflow balance across all zones
- Test building automation system sequences (occupied/unoccupied, economizer, demand limiting)
- Verify fire/smoke damper operation
- Test emergency shutoff sequences
- Measure and document system performance at design conditions
- Produce commissioning report
- Train building operations staff
Clark County Final Mechanical Inspection
The final inspection verifies that the installed system matches the approved plans and that all operational tests pass. Common final inspection items:
- Equipment matches permitted specifications
- All ductwork is accessible for maintenance (access doors at coils, dampers, and filters)
- Condensate drains are functional
- Gas equipment has proper combustion air
- Outdoor equipment has required clearances
- Energy code requirements are met
Complete Timeline Summary
| Phase | Residential Timeline | Commercial Timeline |
|---|---|---|
| Pre-design consultation | 1-2 weeks | 2-4 weeks |
| Load calculation and design | 1-2 weeks | 3-6 weeks |
| Equipment ordering | 1-12 weeks (depending on availability) | 6-12 weeks |
| Permit review | 2-4 weeks | 4-6 weeks |
| Rough-in | 3-7 days | 2-6 weeks |
| Rough-in inspection | 1-3 days | 1-5 days |
| Trim-out and equipment setting | 1-3 days | 1-3 weeks |
| Commissioning and final inspection | 1 day | 1-4 weeks |
| Total (overlapping phases) | 4-6 months | 5-8 months |
The Cooling Company: New Construction HVAC in Las Vegas
The Cooling Company works with general contractors, custom home builders, and commercial developers on new construction HVAC projects across the Las Vegas Valley. We provide design-assist services during the design phase, coordinate with other trades during construction, and commission every system we install.
We understand Las Vegas building conditions — extreme heat loads, attic temperatures, monsoon season, and the Clark County permit process. Our crew schedules account for the summer heat window, and we prioritize rough-in scheduling to keep your project on track.
Call (702) 567-0707 to discuss your next project.
Frequently Asked Questions
When should the HVAC contractor be involved in a new construction project?
For standard production homes, the HVAC contractor should be engaged during design development, at least 60-90 days before the permit application. For custom homes and commercial projects, earlier involvement — during schematic design — prevents costly redesign. The HVAC system competes for physical space with every other trade, and early coordination prevents conflicts that add weeks and thousands of dollars to the construction schedule.
How long does the HVAC rough-in take for new construction?
Residential HVAC rough-in typically takes 3-7 days depending on the size and complexity of the home. Two-story homes with multiple zones take longer than single-story homes. Commercial rough-in ranges from 2-6 weeks depending on building size, system complexity, and the number of zones. In Las Vegas, schedule an additional 30-50% time buffer if rough-in falls during June through September, when attic temperatures exceeding 150 degrees F significantly reduce crew productivity.
What is the biggest cause of HVAC-related construction delays in Las Vegas?
Equipment lead times and late design changes are the two most common delay causes. High-efficiency or commercial equipment can take 6-12 weeks to arrive, and ordering cannot begin until the load calculation and equipment selection are approved. Late architectural changes — moving a wall, changing window sizes, or adding a room — invalidate the load calculation and potentially require equipment re-selection. Order equipment early and freeze the design before HVAC engineering begins.
How many tons of HVAC does a new home in Las Vegas need?
In Las Vegas, new construction homes typically require 1 ton of cooling per 400-500 square feet, depending on insulation levels, window specifications, orientation, and ceiling height. A 2,500-square-foot home might need 5-6 tons, while a 4,000-square-foot home might need 8-10 tons. However, this rule of thumb is only an approximation — a proper Manual J load calculation is required for accurate sizing and is mandatory for the Clark County building permit. Oversizing wastes energy and causes humidity problems; undersizing means the system cannot keep up on 115-degree days.
Should ductwork go in the attic or within the conditioned space in Las Vegas?
Within the conditioned space is always thermally superior. Ductwork in a Las Vegas attic operates in 150-160 degree ambient temperatures during summer, losing 15-25% of its cooling capacity even with R-8 insulation. Ductwork within conditioned space — in soffits, chases, or between floors — loses virtually nothing. However, routing all ductwork within conditioned space requires architectural planning from the beginning of design. Retrofitting conditioned-space duct routes into a design that assumed attic ductwork is expensive and often impractical. If attic ductwork is unavoidable, specify R-12 insulation minimum, mastic-sealed joints, and consider a sealed attic (insulation at the roof deck instead of the ceiling).
How long does the Clark County HVAC permit review take?
Residential mechanical permits in Clark County typically take 2-4 weeks for review, assuming the submittal is complete and passes on the first review. Commercial mechanical permits take 4-6 weeks and frequently require at least one round of corrections and resubmission. Permit review times increase during heavy construction periods (typically spring and fall in Las Vegas). Submit permits as early as possible and ensure the load calculation, equipment specifications, and duct layout documentation are complete to avoid correction delays.
Neighborhoods We Serve for New Construction HVAC
We install HVAC systems in new construction projects across Summerlin, Henderson, North Las Vegas, Enterprise, Centennial Hills, Inspirada, Skye Canyon, Mountains Edge, Cadence, Lake Las Vegas, and all Clark County communities.
Why Builders Trust The Cooling Company
- Serving Las Vegas since 2011
- 55+ years combined experience
- Licensed, EPA-certified technicians
- 100% satisfaction guarantee
- BBB A+ rated
- Lennox Premier Dealer
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Related reading: See our complete commercial HVAC guide for system types and costs. For existing home HVAC evaluation, read our HVAC inspection guide for homebuyers.
Need New Construction HVAC in Las Vegas?
The Cooling Company provides expert HVAC installation for new construction throughout Las Vegas, Henderson, and North Las Vegas. Our licensed technicians coordinate with builders and GCs to keep your project on schedule.
Call (702) 567-0707 or visit AC installation, commercial installation, or commercial HVAC services for details.