The project involves more than swapping an appliance
Once distribution, electrical or venting work is involved, the coordination between them is where the risk sits.
Survey to commissioning, one responsibility
HVAC Contractor in Alderton, WA
- Design and build under one party
- Permits pulled, inspections attended
- Commissioned to documented figures
- Ongoing service after handover
Most of what goes wrong on mechanical projects is not technical. It is the seam between trades. The equipment supplier points at the installer, the installer points at the duct contractor, the duct contractor points at whoever did the electrical, and the building owner is left holding a system that does not perform with nobody willing to own it.
Contracting the whole scope to one party removes that seam. The same organization surveys the building, produces the calculation, specifies the equipment, builds the distribution, pulls the permit, commissions the result and services it afterward.
What full scope contracting covers
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This page describes the whole service rather than a single trade task. It applies to renovations, extensions, conversions, whole system replacements and light commercial fit outs, where the mechanical work involves more than swapping one appliance for another.
The value is in sequence and accountability rather than in any individual piece of work. A project managed as a whole makes decisions in the right order, and the right order is what determines whether the finished system performs.
Sequence, and why it decides the outcome
The most expensive mistakes on mechanical projects are made early and discovered late. Equipment ordered before the load was calculated. Ducts routed before the room by room airflow was known. A condensing appliance specified before anybody checked whether a condensate drain could be routed. Electrical capacity assumed rather than verified.
Each of those is cheap to get right at the start and expensive to correct once walls are closed. Running the project as a single scope means the calculation precedes the equipment selection, the distribution design precedes the routing, and every dependency is identified before anybody orders anything.
It also means the building trades are coordinated against the mechanical requirements rather than the other way around. A chase that needs to exist, a bulkhead that needs allowing for, a slab penetration that needs to happen before the pour: those get raised at the point where they are trivial rather than at the point where they are demolition.
For renovation and extension work in particular, this coordination is most of the job. The mechanical requirements of a converted attic or a new extension have to be settled while the structure is still being planned, because the answer frequently affects the structure.
What is included in a managed project
A building survey covering the envelope, the existing distribution, the electrical and fuel supply, the venting arrangements and every constraint on siting and routing. Room by room load calculations for both heating and cooling. Equipment specification with the reasoning attached, and a distribution design sized against a target friction rate.
A written scope behind a flat rate figure, so what is included is unambiguous and can be compared properly against any other proposal. Permits pulled in our name where the jurisdiction requires them, with the inspections attended rather than left for the owner to arrange.
Installation by employed technicians working to that documented scope, with the site protected and cleared daily and the program sequenced around occupancy. Coordination with other trades where the project involves them, so the mechanical requirements are communicated rather than assumed.
Commissioning with measured values recorded, balancing across rooms, controls configured for the equipment actually installed, warranty registration completed on the owner's behalf, and a handover pack containing the calculation, the commissioning sheet, the permit record and the maintenance intervals.
Commercial and light commercial work
Small commercial premises bring requirements that residential work does not. Ventilation rates are set by code according to occupancy and use rather than by preference. Make up air has to be provided where exhaust is substantial, particularly in food service. Zoning has to reflect how the space is actually occupied across a trading day.
Phasing matters more than in a home. A business cannot close for a week, so work is programd around trading hours, with the disruptive stages placed outside them and the premises returned to a usable state at the end of each shift. That is planned into the schedule rather than improvised.
Documentation requirements are heavier too. Commissioning records, ventilation rate verification and equipment documentation frequently need to be produced for inspection, insurance or a landlord, and assembling that at handover is far easier than reconstructing it a year later.
Ongoing service is usually part of the arrangement rather than an afterthought, because commercial equipment runs far more hours than residential equipment and an unplanned outage costs trading revenue. Intervals are set against actual run hours rather than a calendar.
What single accountability means in practice
It is worth being concrete about this, because it is a phrase every contractor uses and very few define.
It means the calculation that drives the equipment selection and the calculation that drives the duct sizing are the same calculation, produced by the same party, rather than two separate assumptions that happen to disagree. It means the person commissioning the system is measuring against a design they are answerable for, rather than certifying whatever they find.
It means that when the measured airflow at handover does not match the design figure, there is no argument about whose responsibility that is. Correcting it is part of the job rather than the beginning of a dispute between two companies who each priced their own portion correctly.
And it means the documentation is coherent. A handover pack containing a load calculation, a distribution design, a permit record and a commissioning sheet that all describe the same system is worth considerably more, years later, than a folder of unrelated paperwork from four contractors. Whoever services the building next can work from it, including if that is somebody else.
Project stages and what each produces
| Stage | What happens | What you receive |
|---|---|---|
| Survey | Envelope, distribution, services and constraints recorded | A written summary of existing conditions |
| Calculation | Room by room heating and cooling loads | The calculation with its assumptions |
| Design | Equipment specified, distribution sized | A specification you can compare against other bids |
| Proposal | Full scope priced at a flat rate | A written scope, not a one line figure |
| Permitting | Applications made, inspections attended | The permit record |
| Installation | Work carried out to the documented scope | A program and daily site protection |
| Commissioning | Measured, balanced, controls configured | The commissioning sheet |
| Handover | Documents, walkthrough, warranty registration | A pack the next contractor can work from |
How a managed project runs
01
Establish the requirement
What the finished building needs to do, room by room, before any equipment or layout is discussed.
02
Survey and calculate
Existing conditions recorded and loads calculated, which together determine everything that follows.
03
Design and price the full scope
Equipment, distribution, services and builders work identified together and priced against a written scope.
04
Permit, program and coordinate
Applications made, the sequence agreed around occupancy, and mechanical requirements communicated to other trades.
05
Install, commission and hand over
Built to the scope, measured and balanced, controls configured, and documented in a pack you keep.
When full scope contracting is the right approach
A renovation, extension or conversion
Mechanical requirements affect the structure, so they need settling while the structure is still being planned.
Multiple bids that are impossible to compare
Usually a sign the scopes differ rather than the prices. A written scope makes the comparison possible.
A previous project that never performed
Frequently a coordination failure rather than a technical one, and it needs diagnosing as a system rather than repairing as a component.
A commercial premises that cannot close
Phasing around trading hours has to be designed into the program, not attempted afterward.
Documentation is required for a landlord or insurer
Assembling commissioning and permit records at handover is straightforward. Reconstructing them later frequently is not.
You want one party responsible afterward
The value of single accountability is highest on the day something goes wrong, not on the day the contract is signed.
Nobody can tell you what the existing system was designed for
Where no calculation, commissioning record or drawing exists, the first task is establishing what is actually there before anything is added to it.
The building is changing use
Occupancy and use drive ventilation requirements in commercial premises, so a change of use frequently changes the mechanical requirement entirely.
Contracting questions
How Full Scope Projects Are Run
These questions come up whenever a project is larger than a single appliance and smaller than a construction contract.
Because the gaps between separately contracted scopes are where projects fail. A duct contractor sizes to what they were told, an equipment installer fits what was ordered, and if the system underperforms each can point at the other with some justification. A single scope means one calculation drives everything, one party commissions the result, and one party is answerable if the measured figures do not match the design. You can still compare that scope against other bids, which is exactly why it is written down.
Line by line against the written scope, which is why it is provided in that form. The questions that expose the difference are consistent: is there a load calculation and can you see it, who pulls the permit, what distribution work is included, what happens to any appliance orphaned on a shared flue, what commissioning is performed and what figures will be recorded, and who registers the warranty. A cheaper number is frequently a smaller scope rather than better value, and occasionally it is genuinely better value.
Not structural or finishing work, and we say so rather than implying otherwise. What is handled is the mechanical scope in full plus the coordination with whoever is doing the building work: identifying the chases, bulkheads, penetrations and access that the mechanical design requires, at the point in the program where they are straightforward. Where drywall has to be opened for duct work, making good is included in the scope and stated in the proposal.
The commissioning figures are measured against the design, so a shortfall is visible at handover rather than discovered by the occupants a season later. Where measured performance does not meet what was specified, correcting it is our responsibility, and that is the practical meaning of single accountability. Where a genuine concealed condition changed the picture during the work, that is raised at the time with a revised quote rather than absorbed silently or billed as a surprise.
Yes, and most projects are. The program is built around occupancy: which areas are affected on which days, what services are interrupted and for how long, and how the property is left at the end of each day. For residential work the binding constraint is usually heat overnight in winter. For commercial work it is trading hours. Both are planned rather than managed as they arise.
Whatever the equipment warrants. Residential systems generally need annual attention on heating and cooling, with heat pumps needing both. Commercial equipment runs far more hours and is scheduled against run hours rather than a calendar. Because the commissioning figures were recorded at handover, every subsequent visit has a genuine baseline to compare against, which is what turns maintenance from an inspection into a measurement.
Anything where the mechanical work involves more than one discipline. A straight appliance changeout does not need project management and is not priced as though it does. Where it becomes worthwhile is when equipment, distribution, electrical, venting or builders work all have to arrive in the right order: whole system replacements, extensions and conversions, first time central systems, and commercial fit outs. Below that threshold you are better served by booking the individual service, and you will be told so rather than sold a process you do not need.
Also in the catalog
Individual Services Within a Managed Project
Any of these can be contracted alone, or bundled into a single managed scope.
One party, start to finish
Book a Survey for Anything Larger Than an Appliance Swap
Projects fail at the seams between contractors far more often than they fail on technical grounds.
The survey establishes the whole scope, so the proposal describes a complete project rather than the part that was easy to price.
- Survey, calculation and design before any equipment is selected
- A written scope behind every flat rate figure
- Permits pulled in our name and inspections attended
- Coordination with other trades planned into the program
- Commissioned to measured figures and balanced room by room
- A handover pack the next contractor can work from