What to Ask for in an Air Filter Quote for a Brisbane Rooftop Unit

When you are quoting filters for a rooftop package unit, the cheapest line item is not always the safest choice. A clear quote should tell you exactly what is being supplied, how it fits the unit, and whether it will perform as intended on site.

For mechanical contractors, the details matter because rooftop access is often tight, replacement parts need to match the existing setup, and any mismatch can turn a simple changeover into a second trip to site. Here is what to ask for before you place the order.

Start with the exact filter dimensions

The first thing to confirm is the filter size in millimetres, not just a nominal description. Ask for the actual length, width and depth of each filter, especially on rooftop package units where space around the frame can be unforgiving.

If the unit uses multiple filters, check whether the quote is for each panel individually or for the full set. It is also worth confirming:

• •the number of filters required per unit
• •whether the quoted size is the outside dimension or the media size
• •whether there is any tolerance on the frame fit
• •whether the replacement is intended to fit the existing track, clip or holding frame

If you are unsure how to measure a replacement, use how to measure an air filter before requesting the quote. Getting the dimensions right at the start saves time on site and avoids delays when the new filters arrive.

Ask what media type is being quoted

The media is not just a technical label. It affects how the filter behaves in dust loading, how much surface area it has, and whether it suits the service conditions of a Brisbane rooftop unit.

When comparing quotes, ask for the media type and grade in plain language. Useful details include:

• •whether the filter is synthetic, fibreglass, pleated or another construction
• •whether the media is intended for coarse pre-filtration or finer particle capture
• •whether the filter is a standard disposable product or a specialist design for higher dust loading
• •whether the product is part of a commercial range or a custom build

If you need a filter for a specific application, our products and custom air filters pages are a good starting point. For rooftop plant exposed to windborne dust, site conditions and access arrangements often matter as much as the nominal rating, so make sure the quote reflects the real operating environment.

If a supplier mentions ratings such as G3, G4, F5 to F9, or ISO 16890 classifications, ask them to quote the exact product specification rather than relying on a quick conversion. Those rating systems do not translate directly, and the right selection depends on the unit and the site requirements.

Check the frame material and construction

A rooftop filter quote should always identify the frame type. The frame needs to suit the equipment, survive handling, and maintain the seal once installed.

Ask whether the frame is:

• •cardboard
• •galvanised steel
• •aluminium
• •plastic
• •a custom rigid frame

For rooftop units, frame strength and edge finish are important because filters may be changed in awkward conditions and carried across plant platforms or ladders. You should also ask how the frame is joined, whether it is reinforced, and whether it is suitable for repeated handling if the filters will be inspected regularly.

If the system uses a specific holding arrangement, note that in the request. For example, a filter that fits loosely in a frame may look acceptable on paper but still allow bypass air if the surrounding hardware is worn or the dimensions are not matched closely enough.

Confirm the seal and how bypass is controlled

The seal is one of the most important parts of the quote, especially for rooftop package units where vibration, access and weather exposure can affect fit over time. A good quotation should state how the filter seals against the frame and whether any gasket, foam edge, or other sealing method is included.

Ask:

• •is the filter supplied with an integral seal or does it rely on the existing housing?
• •is a foam edge, gasket, or bead included?
• •is the seal designed for one-time installation or repeated removal?
• •are any clips, straps or retaining parts included or required separately?

If the existing frame is damaged, warped or dirty, even the right filter may not seal properly. In that case, it may be worth discussing filter servicing or commercial filter servicing alongside the replacement supply. A supplier should be able to explain whether the quote covers only the filters or the full replacement interface.

Ask about lead time and supply arrangement

Lead time is often the difference between a tidy maintenance job and an urgent return visit. Rooftop filters are sometimes available in common sizes, but many units need a specific fit, special media or a custom frame.

When asking for a quote, confirm:

• •whether the item is stock or made to order
• •the expected dispatch time
• •whether partial supply is possible if part of the order is urgent
• •whether the quote covers pickup, delivery or site delivery
• •whether repeat ordering will use the same drawing or specification

For contractors working on live sites, delivery timing can matter as much as the filter spec. A quote that clearly states lead time helps with shutdown planning and avoids confusion when the maintenance window is short.

Check the operational context before you accept the quote

A rooftop package unit does not operate in a vacuum. Dust loading, access, weather exposure and the condition of the housing all affect what should be quoted.

Before approving the order, ask yourself whether the quote accounts for:

• •the system airflow and filter face area
• •the dust conditions around the site
• •the access method for replacement on the roof
• •whether the equipment has one filter stage or multiple stages
• •whether the quote aligns with the equipment manufacturer instructions

If the building has a specific ventilation design requirement, confirm site needs with the mechanical services engineer or building owner and check the relevant project documentation, including AS 1668.2:2024 where applicable. Inspection frequency should depend on the system, the site conditions and the dust load, and you should follow the filter and equipment manufacturer instructions. Where gauges are fitted, monitor pressure drop so you know when a changeout is actually needed.

Some filters are designed to be washable - check the product instructions before assuming a reuse cycle. Others are intended for replacement only, and treating them the same can cause fit and performance problems.

A practical quote request checklist for contractors

To keep quote requests clear, include the information that helps the supplier quote the right part first time:

• •unit make, model and location
• •actual filter dimensions in millimetres
• •quantity required
• •media type or existing filter description
• •frame material and any special construction details
• •seal type and any retaining hardware needed
• •site access notes and preferred lead time
• •whether the filters are for replacement, trial fit, or a new installation

The more detail you provide, the easier it is to compare quotes from different suppliers on a like-for-like basis. That is especially useful when you are coordinating multiple rooftop units across one site or managing staged maintenance.

Need filters made to suit a Brisbane rooftop unit?

Total Air Filtration is a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, established 2009. We can help supply or make the right filters for rooftop package units, including custom sizes and practical replacement options for site conditions.

If you are ready to compare options, call 07 3800 3448 or request a quote. You can also browse our products or get in touch through contact us.