FlexiBaffle FAQs

Your questions answered: everything you need to know about the FlexiBaffle and how it improves fish passage.

How do I know what size, and how many FlexiBaffle's I need for my culvert?

Use our Culvert Solution Tool to get a tailored FlexiBaffle recommendation. Just enter your culvert’s diameter, gradient, shape, and a few other details – we’ll respond with the ideal baffle size, spacing, and a schematic drawing.

What is a FlexiBaffle?

A FlexiBaffle is a flexible weir or culvert baffle installed in culverts to improve fish passage. It increases water depth, slows water velocity, and creates resting areas for fish and other aquatic life. Its flexible design allows debris and high flows to pass through without causing blockages or reducing hydraulic capacity.

How do FlexiBaffles help fish passage?

FlexiBaffles create turbulence and low-velocity zones that mimic natural stream features. This helps fish overcome otherwise impassable culverts, supporting fish migration and improving aquatic connectivity — especially for native species in New Zealand.

What species benefit from FlexiBaffles?

They improve passage for a wide range of aquatic organisms including fish, eels, lamprey, amphibians, reptiles, and invertebrates by transforming fast, shallow culverts into more passable environments.

What are the advantages over solid baffles?

  • No major flow restriction: Flex during floods to maintain capacity

  • Less debris build-up: Flexible design passes debris without clogging

  • Simpler installation: No dewatering or heavy retrofitting required

  • More cost-effective: Lower material and labour costs

  • Custom fit: Easily shaped for different culvert types

  • Durable: Withstand debris impact and extreme flows

How do they compare in cost?

Installing FlexiBaffles costs a fraction of culvert replacement or removal—often less than 1%—while avoiding disruption to infrastructure or traffic.

How long does installation take?

Each baffle takes minutes to install. A crew can retrofit 4–8 culverts per day using standard tools, without needing to dewater the culvert.

Can they be installed in existing culverts?

Yes. FlexiBaffles can be fitted in both existing and new culverts—even before installation.

Are they suitable for any culvert shape?

Yes. FlexiBaffles can be installed in round, box, or arch culverts. Relief cuts allow flexible shaping to match uneven or curved surfaces.

What are they made from?

They’re made from EPDM—an extremely durable, non-toxic synthetic rubber with excellent resistance to abrasion, chemicals, UV, and temperature extremes.

How long do they last?

They’re designed to last 10+ years. Some installations have remained effective for over 15 years with routine inspections.

Can they be used in all culvert materials?

Yes. FlexiBaffles are compatible with concrete, metal, and plastic (HDPE) culverts.

Where are they used?

Originally developed in New Zealand, FlexiBaffles are now installed globally—including Australia, Europe, the U.S., and Canada.

Do they create microplastics?

No. EPDM is a rubber, not plastic. It’s non-toxic, recyclable, and doesn’t break down into microplastics.

Do they contain harmful chemicals like 6PPD-quinone?

No. FlexiBaffles are free of 6PPD-quinone and other toxic substances.

How do they affect hydraulic capacity?

FlexiBaffles increase Manning’s “n” value by about 10–30%. They’re designed to flex under high flows, preserving culvert capacity.

Do they trap debris?

No. Their flexible design allows debris to pass during high flows. Once water levels drop, the baffle resets to improve fish passage.

Need Assistance?

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