HVAC Design Engineer for Mechanical Permit Plans
Load calculations, equipment selection, duct design and ventilation plans prepared by an HVAC design engineer and sealed for your building department.
- Stamped by a PE licensed in your state
- Built to IBC, IRC and local amendments
- Plan-check comments answered
Heating and cooling sized to the building, not a rule of thumb
Oversized equipment short-cycles, leaves rooms humid and wastes money. Undersized equipment cannot keep up on the hottest and coldest days of the year. An HVAC design engineer replaces the old square-feet-per-ton shortcut with calculated loads, so the equipment, ducts and ventilation fit the way the building is actually built and used.
PE Engineer prepares mechanical plans for homes, additions, ADUs, offices, retail spaces, restaurants, gyms, warehouses and light industrial buildings. Residential designs follow ACCA Manual J, Manual S and Manual D. Commercial designs follow ASHRAE load methods, with outdoor air calculated to ASHRAE 62.1 and efficiency checked against the energy code. Every set is sealed by a Professional Engineer licensed in the state where the project is located.
The mechanical plan is coordinated with the rest of the permit set. Equipment loads go onto the electrical plans, gas appliances get properly sized gas piping, and rooftop units get a curb and roof support check before anyone cuts a hole in the roof. When a project includes a commercial kitchen, the hood exhaust and makeup air are designed in the same set.
What you receive
- Heating and cooling load calculations
- Mechanical floor plan with duct layout
- Equipment, diffuser and fan schedules
- Outdoor air ventilation calculations
- Mechanical details and general notes
- PE stamped PDF set ready to submit
HVAC systems we design
We choose the system type with you, based on the building, the climate, the budget and how the space will be used.
Split systems and heat pumps
Ducted and ductless split systems, heat pumps and furnaces for homes, additions and ADUs, selected with Manual S so capacity matches the calculated load at your local design temperatures.
Packaged rooftop units
Rooftop units for retail, office and restaurant spaces, with zoning, economizers, outdoor air, curb details and coordination with the structural engineer for the added roof load.
VRF and multi-zone mini-splits
Variable refrigerant flow and multi-zone mini-split layouts with refrigerant piping routes, condensate disposal and the refrigerant concentration checks the mechanical code requires for occupied rooms.
Ventilation and exhaust
Outdoor air and exhaust for restrooms, locker rooms, janitor closets, parking garages and process areas, calculated to ASHRAE 62.1 for commercial spaces and ASHRAE 62.2 or the IRC for homes.
Duct design and air distribution
Duct sizing by Manual D or the equal-friction method, diffuser and grille selection, fire and smoke damper locations, and static pressure checks against the fan performance.
Hydronic and specialty systems
Boilers, radiant floor heat, gas-fired unit heaters for shops and warehouses, and dedicated cooling for server rooms and other spaces with heavy internal heat gain.
Your Stamped, Permit-Ready Plans Start With One Upload
Send your drawings or describe the project. A licensed engineer reviews it and sends a clear, fixed-fee proposal, often within hours.
- Free and no obligation
- Reviewed by a licensed PE
- Secure file upload
What an HVAC design engineer delivers for permit
A mechanical permit set tells the plan reviewer three things: how much heating, cooling and ventilation the building needs, what equipment provides it, and how the air gets where it needs to go. Our mechanical drawings typically include:
- Load calculations showing design temperatures, envelope assumptions, occupancy and internal gains for each zone.
- A mechanical floor plan with equipment, supply and return ductwork, diffusers, grilles, exhaust fans and thermostat locations.
- Equipment schedules listing capacity, airflow, efficiency, electrical data and weight for every unit, so the electrician and structural engineer can design around them.
- Ventilation calculations proving that each space receives the outdoor air the code requires.
- Details and notes covering roof curbs, condensate disposal, duct construction, insulation, fire dampers and controls.
For small residential projects the set may be a single sheet plus a Manual J report. For a restaurant or a multi-tenant building it can run several sheets. Either way, it is drawn to the mechanical code your jurisdiction has adopted.
We also print the design assumptions on the drawings themselves, including indoor and outdoor design temperatures and occupant counts, so a plan reviewer or a future engineer can see exactly what the system was sized for.
Residential HVAC design with Manual J, S and D
The International Residential Code requires heating and cooling equipment to be sized from loads calculated with ACCA Manual J and selected with ACCA Manual S. Many building departments now ask to see that report at permit, especially for new homes, additions and ADUs.
- Manual J calculates the heat gained and lost through walls, windows, roof, floors and air leakage, room by room, at the design temperatures for your location.
- Manual S selects equipment whose actual capacity, at your design conditions, covers the load without gross oversizing.
- Manual D sizes the supply and return ducts so every room receives its share of air at the static pressure the blower can deliver.
Getting all three right is what prevents the familiar complaints of a hot upstairs bedroom, a noisy return grille or a system that runs constantly and never quite catches up.
For an addition, we check whether the existing system has spare capacity or whether the new space needs its own heat pump or mini-split. For an ADU we typically design an independent system, which simplifies the electrical and keeps the occupants in control. The load calculation also feeds the energy code compliance report, so the two documents tell the same story.
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Skip the guesswork. Chat live with a licensed engineer about your drawings, code requirements or permit comments, free and with no obligation.
- Free and no obligation
- Reviewed by a licensed PE
- Secure file upload
Commercial mechanical design and ventilation
Commercial buildings fall under the International Mechanical Code or, in California and some other western jurisdictions, the Uniform Mechanical Code. Plan reviewers focus on ventilation, exhaust, equipment efficiency and fire safety.
Outdoor air is calculated with the ASHRAE 62.1 ventilation rate procedure, which combines a per-person rate with a per-square-foot rate for each occupancy category. A gym, a classroom and an office of the same size need very different amounts of outside air, and a change of use often means the existing rooftop unit cannot deliver enough. We check that before you sign a lease, not after the plan checker does. Where occupancy varies through the day, demand-controlled ventilation can reduce the outdoor air load, and in some cases the energy code requires it.
For restaurants, the kitchen hood exhaust and makeup air dominate the mechanical design. We size the rooftop units and the makeup air unit together so the dining room stays slightly positive, doors open normally and the hood captures smoke the way it should.
Exhaust is designed for restrooms, janitor rooms, locker rooms, parking garages and any space with odors or contaminants. We show economizers and controls where the energy code requires them, fire and smoke dampers where ducts cross rated walls and floors, and duct smoke detectors on larger air handlers. Heavy rooftop equipment is checked for support and anchorage, and where wind or seismic forces govern, we coordinate with our equipment anchorage design.
What we need to start your mechanical plans
To quote and design the HVAC system we need the project address, the architectural floor plans or a dimensioned sketch, and a description of how each space will be used. Details about wall and roof insulation, window types and ceiling heights help us build an accurate load model.
For work in an existing building, send photos of the equipment nameplates, the existing ductwork where it is visible, and the electrical panel that serves the HVAC equipment. For commercial spaces, the landlord’s tenant criteria and any rooftop unit maintenance reports are useful, because they tell us whether existing equipment can be reused. If the owner has already purchased equipment or prefers a particular manufacturer, tell us, and we will design around the real model numbers instead of generic capacities.
If your building department has already issued plan-check comments, include them. We will address each comment by number in a response letter and revise the drawings and calculations at no extra charge within the original scope.
Most residential mechanical packages are completed within a few business days of receiving complete information. Commercial timelines depend on the size of the building and the number of systems. Rush delivery is available when your schedule depends on it.
You likely need this if
- Your city asked for Manual J calculations
- You are adding or replacing rooftop units
- A tenant space is changing use
- An addition will tie into existing ductwork
- A commercial space needs outdoor air design
- Restrooms or garages need exhaust design
How it works, start to finish
From your first message to stamped drawings, you work directly with the engineering team.
- 1Share your projectSend the address, scope and any drawings, photos or plan-check comments. Two minutes is enough.
- 2Receive a fixed-fee proposalAn engineer reviews the scope and replies with a firm price and delivery date for your mechanical & hvac design drawings.
- 3Engineering and draftingWe run the calculations and prepare drawings to the codes your jurisdiction enforces, checked before sealing.
- 4Stamped set deliveredYou receive a sealed PDF set ready to submit, and we answer any plan-check comments within scope.
Codes and standards we design to
Mechanical designs are prepared to the edition of each code your jurisdiction has adopted, including local amendments:
- International Mechanical Code (IMC) or Uniform Mechanical Code (UMC)
- International Residential Code (IRC) mechanical provisions for dwellings
- ACCA Manual J, Manual S and Manual D for residential systems
- ASHRAE 62.1 and ASHRAE 62.2 for ventilation
- IECC and ASHRAE 90.1 for equipment efficiency and controls
- International Fuel Gas Code (IFGC) for gas-fired equipment
- ASHRAE 15 for refrigeration system safety
How licensing works. Engineering drawings must be sealed by a Professional Engineer licensed in the state where your project is located. PE Engineer works with a network of state-licensed PEs, so every set is reviewed and stamped by an engineer with an active license in the state where your project is located. Their name and license number appear on the seal, exactly as your building department requires.
Related services
Energy Code ComplianceREScheck, COMcheck and Title 24 energy compliance calculations for homes, additions and commercial buildings, prepared to the IECC or ASHRAE 90.1.Explore More
Kitchen Hood & ExhaustType I and Type II hood, grease duct, exhaust fan, makeup air and fire suppression design to NFPA 96 and the IMC, sealed for permit.Explore More
Electrical PlansElectrical load calculations, panel schedules, one-line diagrams, lighting and power plans prepared to the NEC and sealed by a licensed PE.Explore MoreFrequently asked questions
What is a Manual J load calculation and does my city require one?
Manual J is the ACCA method for calculating room-by-room heating and cooling loads in homes. The IRC requires equipment to be sized from Manual J loads and selected with Manual S, and many building departments ask to see the report with the permit, especially for new homes, additions and ADUs.
Can you design HVAC for a commercial tenant improvement?
Yes. We lay out supply, return and exhaust, check the existing rooftop units against the new loads, calculate outdoor air to ASHRAE 62.1, and show any new or relocated equipment. The plans are coordinated with the electrical and architectural sheets so the set reads as one package.
Do I need an engineer or can my HVAC contractor draw the plans?
For many single-family jobs a contractor’s layout and load calculation is accepted. Commercial projects, larger buildings and jurisdictions with stricter review usually require mechanical plans sealed by a Professional Engineer. Where the city allows it, we can also review and stamp a contractor’s design.
Can you size a mini-split or heat pump for my addition or ADU?
Yes. We run Manual J for the new space, select equipment with Manual S, and show the indoor and outdoor unit locations, line set routing, condensate disposal and electrical requirements, so your installer and inspector are working from the same plan.
How long do mechanical plans take?
Most residential mechanical packages are delivered within a few business days of receiving complete information. Commercial timelines depend on building size and how many systems are involved. Rush service is available, and we quote a fixed fee up front, usually the same day.
What happens if plan check comments on my mechanical drawings?
Send us the correction list. We answer each item in a response letter, revise the calculations and drawings, and reseal the set. Revisions within the original scope are included at no extra charge, so you are not paying twice to get the permit issued.
Get your free mechanical & hvac design proposal
Tell us where the project is and what you need. Attach any drawings, photos or plan-check comments. A licensed engineer reviews every request.
- Upload your filesPlans, sketches, photos or comments
- Get a fixed-fee proposalUsually the same day
- Receive stamped drawingsSealed by a PE licensed in your state