HVAC Estimating Services for Mechanical Contractors

Ductwork is measured from the mechanical plans by size and length, system by system. Supply, return, exhaust and outside air are kept separate, because they often have different pressure classes, materials and insulation. Every elbow, transition, tee, takeoff and offset is counted, since fittings take more labor and material than straight duct.

For rectangular duct, we can convert lengths to sheet metal weight. The gauge for each size comes from the specification or SMACNA duct construction standards for the pressure class, and the weight is calculated from the surface area of the duct and the weight of the sheet. Round and spiral duct, flex duct, and lined or double-wall duct are listed by size and length.

Equipment is listed from the mechanical schedules with model, capacity and quantity: rooftop units, air handlers, split systems, VAV and fan-powered boxes, exhaust fans, unit heaters, energy recovery units and more. We add the items around the equipment that are easy to forget.

• Roof curbs, rails, supports and seismic or wind restraints
• Crane and rigging for rooftop equipment
• Condensate drains, refrigerant line sets and hydronic connections
• Thermostats, sensors and controls, when they are in your scope
• Startup, testing, adjusting and balancing (TAB), when required

• Exposed duct: exposed spiral duct in open ceilings needs better finish and support than duct hidden above a ceiling.
• Pressure class and sealing: higher pressure classes need heavier gauge, more reinforcement and more sealing.
• Insulation: external wrap, internal lining and outdoor duct jacketing all change material and labor.
• Access: tight ceiling spaces, high bay ceilings and occupied buildings slow installation.
• Replacement work: removing and disposing of old equipment, refrigerant recovery and reusing existing duct.

Commercial HVAC estimates follow CSI Division 23 or your own breakdown, with separate sections for equipment, ductwork, air distribution, piping, insulation, controls and TAB.

Residential HVAC estimates are usually priced per house plan: equipment, duct system, registers and grilles, line sets, thermostats and venting. If you need a load calculation or duct design rather than an estimate, our MEP design team can help.

• Fire and smoke dampers and their access doors
• Kitchen hood exhaust and make-up air
• Duct cleaning, temporary filters and protection during construction
• Electrical connections that the specs assign to the mechanical contractor
• Louvers, roof hoods and wall caps
• Permits, startup and warranty requirements in the specs

Office and retail projects are usually rooftop units, VAV or constant volume duct systems and simple controls. Restaurants add kitchen exhaust, grease duct and make-up air, which need special materials, fire wrap or shafts and inspections. Healthcare and laboratory projects need higher filtration, pressure relationships, more air changes and heavier duct construction. Warehouses rely on large rooftop units, unit heaters, exhaust fans and destratification fans over large open spaces.

Multifamily HVAC is often split systems or packaged terminal units in each apartment, with bath and dryer exhaust risers. We price each unit type once and multiply it, then add corridors, amenity spaces and roof equipment.

• Is the duct galvanized steel, aluminum, stainless or fiberglass board, and what pressure class applies?
• Is duct insulation external wrap, internal lining or both?
• Who supplies and installs controls, and who wires the thermostats?
• Is TAB carried by you or by a separate firm hired by the owner?
• Are there existing systems to remove, reuse or keep running during construction?

When the drawings leave a question open, we list our assumption in the clarifications so your proposal is clear.

A detailed HVAC estimate keeps working after the bid. Duct quantities by size and weight become the basis for your sheet metal shop or fabrication quotes. The equipment list goes straight to your supplier for buyout, and air distribution counts become your order for grilles, registers and diffusers.

The line items also help you build a schedule of values that matches how the job will be billed, such as rough-in duct, equipment set, trim-out, startup and TAB. When the design changes, you can price the change from the same quantities instead of starting over, which makes change orders faster and easier to defend.

• Ductwork quantities by size, length and weight, with fittings
• An equipment list from the schedules
• Air distribution counts by type and size
• Labor and material costs for each line, priced for your location
• Clarifications and exclusions, in Excel and PDF