Hi @g1nny,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Understandably you'd like the timber you use to be untreated. As a bird lover myself, I think this is fantastic, but you should be aware that this makes your birdhouse susceptible to rot from exposure to the elements. It wouldn't be an immediate thing, but you may need to replace the timbers or build a new birdhouse over time.
Unfortunately, I'm fairly certain that the list you have read is from an American source as most of these timbers are not commonly available in Australia and New Zealand. I'll recommend some alternatives that are more available in our region.
Pine is the most readily available untreated timber on your list. Our stores stock untreated Pine DAR in a variety of lengths and profiles. This is a lightweight, cost-effective and easy-to-use material that is worth considering but you should be aware that untreated it is on the lower end of the durability scale.
Our stores also stock Tasmanian Oak DAR which is also untreated and safe for use around animals. This is a harder timber that is naturally more durable than pine but is still on the lower end of the durability scale.
Using hardwood timber is the best way to increase durability without the need for treatment. Hardwoods are not as readily available but can often be ordered through your local Bunnings' Special Orders or Trade desks. Timber suppliers are often regional, so it is best to speak with the team at your local Bunnings to check what is available near you.
Common Australian hardwoods that would be great for this application and can be expected to last longer than Pine or Tasmanian Oak include Jarrah, Blackbutt, Spotted Gum and Ironbark. These timbers can be purchased untreated and are often used as decking for their aesthetics and natural durability. If you'd like to explore these options, head in-store and speak to the team at the Trade or Special Orders desks as they will have knowledge of the local timber suppliers.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
Please be kind. xo.
