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Treated Pine Timber Hazard Ratings, What Should I Use and Where?

Treated Pine Timber Hazard Ratings, What Should I Use and Where?

What type of timber should you use when building your patio, pergola or decking? This question can be answered by asking your local timber mill or timber supplier and explaining what it is you are building and what type of hazards your structure is likely to be exposed to.The ‘H’ rating or hazard rating of treated pine is what we will explain in this blog and explain why they are extremely important to your new buildings design.

Timber Hazard Ratings

H1: Used indoors, above the ground and is not resistant to termites.
H2: Used indoors, above the ground and is resistant to termites.
• H2F: Same as H2. Seen in blue construction pine as sold at Bunnings.
• H2S: Same as H2. Seen in LVL and plywood
H3: To be used outdoors, above the ground and is resistant to termites.
• H3A: Same as H3. Used in fascia boards, doors and timber that is regularly maintained using paint.
H4: Used outdoors, in ground with water contact and is resistant to termites.
H5: Used outdoors, in ground with water contact and is resistant to termites.
H6: Used when in constant contact with salt water.

There are many options when it comes to each rating and to fully understand each, you must consider what each piece of timber will be exposed to in its lifespan. We build predominantly outdoors and because of this we use H4 posts in-ground as a minimum. The difference between H4 or H5 may be a slightly higher cost for a slightly longer lifespan but we are yet to see the difference in the residential market. Anything attached to our posts is generally H3, unless it is in constant contact with the ground. The choice of hazard rated timber is ultimately up to you but the difference between a few dollars now can make your build last considerably longer!

There is always the option to use a waterproofing agent or builder’s plastic around the base of each post in-ground if you want more protection against timber decay. If in doubt, call a professional for more information.