What to Include in a Scope of Works for HVAC Filter Replacement Contracts

When an HVAC filter replacement contract is vague, the quotes usually are too. A good scope of works gives contractors the same information up front so they can price the same equipment, the same access, and the same service expectations without assumptions.

For facility managers, property managers and mechanical contractors, the aim is simple: define the job clearly enough that you reduce variations later, while still allowing the contractor to inspect site conditions and confirm the final details before work starts.

Start with the system details that matter

The first part of any scope should identify exactly what system the contractor is working on. That includes the obvious items, but also the details that often get missed.

Include:

• •Site name and exact location of the plant or units
• •Building areas served by each air handling unit or packaged system
• •Unit tags, filter bank numbers, or any other identification used on site
• •Whether the filters are in return air, outside air, supply air or terminal locations
• •Access constraints such as roof access, ceiling voids, locked plant rooms or working at height
• •Any shutdown requirements or time windows for the work

If the building has drawings or asset registers, attach them. If not, ask the contractor to confirm equipment identification during site inspection before final pricing. If dimensions or access are uncertain, it is worth reviewing how to measure an air filter so everyone is speaking the same language.

Specify the filter type, size and performance basis

This is where many scopes become too loose. Saying only “replace filters” leaves room for different interpretations, especially where several filter stages are installed in the same system.

A useful scope should list:

• •Filter stage and location, such as pre-filter, final filter or terminal filter
• •Exact dimensions of each filter, including depth
• •Frame style and seal type, where relevant
• •Media type if it is known and important to the application
• •Rating or grade required, using the system’s existing specification or the relevant design documentation
• •Any special construction requirements, such as rigid frames, bag filters, pleated panels, or high-efficiency filters

Where a building is designed to suit a particular standard or engineering basis, note that the site requirements should be confirmed with the mechanical services engineer or building owner. In some projects, AS 1668.2:2024 may be relevant to the ventilation design, but the scope should reflect the actual site requirements rather than assuming one standard fits every system.

If you need filters made to size or to suit non-standard housings, include that in the scope and link it to custom air filters or the relevant supplier drawings.

Define exactly what the contractor is replacing

A common source of variation is uncertainty about whether the contractor is replacing only the filter media, the whole filter, or associated hardware as well.

Spell out whether the contract includes:

• •Supply and replacement of all nominated filters
• •Removal of spent filters from housings, tracks or frames
• •Replacement of damaged gaskets, seals or retaining clips where needed
• •Cleaning of filter housings before refitting new filters
• •Inspection of frames and tracks for obvious damage or bypass gaps
• •Re-sealing where the housing design requires it

If some filters are washable, do not assume that means they should be washed on site. Some filters are designed to be washable - check the product instructions. If the scope is for replacement only, make that clear so there is no confusion between cleaning, reconditioning and replacement.

It also helps to state whether the contractor is expected to supply genuine replacements to match the installed system, or whether suitable alternatives may be proposed for approval. If alternatives are acceptable, say what information must be provided for review, such as dimensions, rating, frame type and pressure drop data.

Include access, safety and working conditions

Many filter jobs become more complex because the scope does not explain how the work will be carried out. A contractor can only quote accurately if they know what conditions they are walking into.

Include site requirements such as:

• •Induction or site entry procedures
• •Permit-to-work requirements
• •After-hours access or noise restrictions
• •Working at heights, confined spaces or roof access controls
• •Isolation requirements for fans or plant during the changeover
• •Any contamination controls needed around the work area
• •PPE and housekeeping expectations

If the site has sensitive areas, such as food processing spaces, laboratories, healthcare areas or dust-sensitive production zones, say so in the scope. Even if the contractor is experienced, the way the work is done may need to change to suit the site.

Where the project includes specialised environments, it can help to reference the relevant building zones and the kinds of industries we supply so the contractor understands the operating context.

Set out disposal and cleaning responsibilities

Spent filters are not just a supply item; they also need to be removed, handled and disposed of properly. If you do not define this, contractors may price it differently or add variations later.

Your scope should state:

• •Who removes and disposes of used filters
• •Whether bags, wrapping or containment are required for dirty filters
• •Whether dust and debris in the filter chamber are to be cleaned up as part of the job
• •Who provides disposal documentation if required by the site
• •Whether filters are to be stored temporarily in a nominated area before collection

If filters are contaminated with mould, dust, industrial residues or other site-specific material, the contractor needs to know that in advance so they can plan the work safely and quote accordingly.

Ask for reporting, not just replacement

A good scope of works should result in more than a pile of new filters and an invoice. It should also give the facility team enough information to manage the asset properly after the work is done.

Ask the contractor to provide:

• •A service report listing each unit attended
• •Filter types and sizes installed
• •Any damaged frames, seals or housings observed
• •Any issues with access, installation or airflow paths
• •Notes on pressure drop readings where gauges are fitted
• •Photos if the site requires them

If the system has differential pressure gauges, include in the scope that readings are to be checked and recorded where available. Inspection frequency should be based on the system, site conditions and dust load, and the filter or equipment manufacturer instructions should be followed. A pressure rise can help signal when a filter change is needed, but it should be interpreted in the context of the actual system rather than guessed.

Make allowances for variations and exclusions

Clear exclusions are just as important as inclusions. If you want comparable pricing, the scope should say what is not included unless specifically listed.

Common points to clarify include:

• •Emergency call-outs versus planned maintenance
• •Replacements beyond the nominated quantities
• •Rectification of pre-existing damage to housings or ductwork
• •Supply of access equipment such as scissor lifts or scaffolding
• •Major cleaning outside the immediate filter housing
• •Replacement of sensors, gauges or dampers unless nominated

It is also worth asking contractors to list any assumptions in their return. That way, if they have priced on the basis of a particular access method, filter brand, or shutdown window, you can compare the quotes properly and identify where they differ.

A practical scope makes contract management easier

A filter replacement contract works best when the scope is specific enough to remove guesswork, but flexible enough to reflect real site conditions. The more clearly you define the equipment, filter types, access needs, disposal requirements and reporting expectations, the fewer surprises you are likely to face later.

If you need help identifying the right replacement filters for an existing system, Total Air Filtration can supply or make filters to suit commercial and industrial applications from our family-owned business in Hillcrest, Brisbane QLD, established 2009. Call 07 3800 3448 or request a quote. You can also view our products or contact us if you want to discuss a scope before sending it to tender.