H6 treated pine: the marine rating and where it fits
H6 is built for seawater. If you are standing in a backyard wondering which class to buy, it is almost certainly not the one.
What H6 treated pine is
H6 is the top hazard class in AS 1604. It is written for timber that sits in or splashes through seawater, such as jetty piles, marine pilings and wharf bracing. The threat it answers is marine borers, which chew through untreated wood below the tide line.
It is not a stronger H5 for the garden. It is a different job. Most of what you see sold as treated pine for houses, decks and fences is H2, H3, H4 or H5.
H6 against the classes below it
| Class | Typical use |
|---|---|
| H2 | Inside the house, above ground, protected from the weather |
| H3 | Outdoors above ground, such as decking and pergolas |
| H4 | In ground contact, such as fence posts |
| H5 | Heavy ground contact, such as piers and poles |
| H6 | Marine use, in or over seawater |
If your project is on dry land, the real choice is between H3, H4 and H5. See H5 treated pine for the heavy ground contact end of that range.
Do you ever need H6 at home?
Almost never. A seawall, a jetty or a boat ramp is the territory. A waterfront house does not need H6 framing just because the sea is nearby, because the frame is not sitting in the water.
Buying a higher class than the job needs does not make a house safer from termites. It only changes how the wood is treated, not how a colony finds the building.
Does H6 stop termites?
No more than any other class does. Treatment makes that piece of wood less appealing and harder to digest. Subterranean termites can still build mud tubes across a treated surface to reach untreated timber behind it.
The protection for a building is a termite management system and regular inspections, not a hazard number. Termite treated timber explains what the label does and does not promise.
Where H6 can go wrong
- Using it as a shortcut. Specifying H6 for a bearer because it sounds safest wastes the rating and adds nothing against termites.
- Cutting it and leaving the cut bare. Every cut end and drill hole exposes less treated core. Seal it as the supplier directs.
- Assuming it is forever. Marine timber still ages, and borers still win where treatment is thin.
- Mixing up the class with the species. The number is a treatment level. It tells you nothing about the pine itself.
If you find damage in any timber
Mud tubes, hollow-sounding wood or fine frass mean stop and leave it alone. Do not spray it, break the tubes or pull the timber out. Disturbing a colony makes it retreat and return somewhere hidden, and it destroys the evidence an inspector needs.
Book a licensed timber pest inspection. Any treatment is for a licensed pest management technician using APVMA registered products. This site does not certify any product or brand.
Frequently asked questions
What is H6 treated pine used for?
H6 is for timber in or over seawater, such as marine piles and jetty bracing, where marine borers attack. It is not a house framing class.
Is H6 better than H5?
Only for marine use. On dry land H5 already covers heavy ground contact, so H6 adds nothing for a pier or a post.
Is H6 treated pine termite proof?
No. Treatment makes that timber a poor meal, but termites can still tube over it to reach untreated framing. A termite management system and regular inspections protect the house.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- Department of Health, Victoria. Pest control - termites
- Queensland Building and Construction Commission. Protect against termites - termite management systems and inspections
- Standards Australia. Australian Standards (AS 3660 termite management, AS 4349.3 timber pest inspection)