I am researching an interpretation of the timber framing code relating to, Residential timber-framing construction part 2, Non-Cyclonic areas AS 1684.2-2010 vol. (pg 142-144) 8.3.6. Table 8.18 A, B, C, D. In the referred table diagrams the bracing states two forms of unit measuring, a millimeter and a degree. Min 1800mm – Max 2700mm and a range between 30 & 60 Degrees. In some diagrams there is only one unit of measurement illustrated and vis versa on another, but they equal the same KN/m capacity in the KN/m table. On the other illustrations it shows both the millimeter and degrees unit of measurement in the same diagram again with only one KN/m capacity measurement. Are these units of measurements to be read in conjunction with each other or are they an option and can be either one or the other. Eg, 2700mm high wall frame and a brace be used at 30degrees (that will exceed the 2700mm maximum other written measurement. The timber framing code in this section only gives the maximum height of 2700mm to work with so a minimum is what ?. As this is not stated do we presume that the minimum wall height is of bathrooms, passages or similar at 2.1m or stairway and landing of 2.0m in framing height. If its to either then the degrees can only be a fixed maximum and a fixed minimum specific degree measurement. If we work on 1.0m high balustrade framed wall then at neither 1800 and 2700mm min-max brace length complies to the minimum 30degrees. To my understanding you can select between either bracing unit of measure Eg. 2700mm high wall frame can have a brace at 30degrees (this exceeds the max length of 2700mm), and to my understanding a 30degree brace is a stronger brace with less uplift force than a 45degree brace if working to a max wall height 2700mm and max brace length of 2700mm. This is hard to fully explain via a written explanation so I hope it makes sense.
We note that your question relates to AS 1684.2-2010, but there is now a 2021 edition of AS 1684. However, the requirements for angle bracing in AS 1684.2-2021 remain the same. All the elements in the bracing system are used together. For example, in Table 8.18 (a), for wall heights up to a maximum of 2.7 m, each of the “Two diagonally opposed timber or metal angle braces” must comply with the following criteria: (1) the horizontal length of the angle brace must be a minimum of 1 800 mm up to a maximum of 2 700 mm and (2) the angle the brace forms to the horizontal can be between 30 degrees and 60 degrees. These criteria can be in any combination of the two. If your wall height is 2.0 m, the two requirements apply as per Table 8.18. If your wall is higher than 2.7 m then reductions are applied to its capacity as per clause 8.3.6.4. The range of angles and max and min horizontal lengths gives some flexibility without compromising bracing capacity, namely 0.8 kN/m.
Are there any products that may be applied to H2 rated timber in a building (floor joists), which may protect the timber to H3? i am looking at lengths of up to 1.5m of floor joists that need to be H3 rated. Is there any way of achieving this, without having to replace the timber?
You will find aerosols and brush-on products on the net described as H3 treatments, but they are 'supplementary products' intended for treating cut ends and notches in timber that has been through a preservative treatment plant. They are not marketed as an alternative to H3 pressure treatment. H3 treatment penetrates into the timber and provides protection against termites and wood rot. H2 treatment protects timber only against termite attack. Since your floor joists will be shielded from the weather they may not need H3 treatment, assuming there is adequate sub-floor ventilation to maintain a dry environment. Note that H3 treatment is one way of dealing with sites that are excessively damp or subject to frequent flooding, according to the ABCB Housing Provisions, but is not required for above-ground floor framing in other circumstances.
Can you do a diagram with metal fascia as your diagram now is with timber fascia?
Metal or timber fascias can be used in BAL-FZ areas, over fire-resistant linings. This is shown in our Regulatory Information Report RIR 23626A which can be downloaded from our website free of charge via this link https://www.woodsolutions.com.au/resources/standards-codes/fire-test-reports. Refer section 9 of the report for details of the fire resistant fascia linings, and section 10 for installation of the fascia itself.
