Non-structural timber grading requirements under the law in Vietnam

Hello, Lawnet would like to answer as follows:

1. What are the regulations on non-structural timber grading in Vietnam?

TCVN 10573:2014 stipulates non-structural timber produced from broadleaf and coniferous species. Non-structural timber is classified into two basic systems used to visually evaluate timber, including:

- The first visual grading system uses a grading scheme based on the amount of beneficial use of the non-structural timber specimen compared to the portion considered unusable for use.

+ A grading system of this type determines the usefulness of a test specimen by using “sections” or other similar means to eliminate unwanted defects; from there, it determines the beneficial use of the test sample.

+ Non-structural timber products manufactured under this type of grading system often require additional processing to obtain a product that can be used indoors or outdoors, usually on exposed, shiny surfaces.

- The second visual grading system uses a grading scheme based on the usability of the overall length of the test piece. Non-structural timber products manufactured using this type of grading system are extensively used in construction applications and are generally not intended for further processing.

Specifically, the grading of non-structural wood is as follows:

- Regarding general regulations: non-structural timber must be classified based on use, level of processing, and minimum standard size.

- Instructions:

+ Timber in storage: non-structural timber is timber of all grades, sizes and patterns intended for use in non-structural construction.

+ Factory timber and store timber: Non-structural timber is wood that is produced or selected for reprocessing and intended for use in non-structural projects.

- Level of processing: Non-structural timber is classified based on the surface processing of the wood, such as standard timber, surface processed wood, processed wood to standard dimensions, and shaped wood.

- Sizes of standard non-structural timber: Minimum standard sizes of standard timber and surface-treated timber must be given in the grading rules.

2. What are the rules for grading non-structural timber in Vietnam?

According to TCVN 10573:2014, the rules for classifying non-structural timber are as follows:

- Regarding general regulations

+ The grading process includes classifying non-structural timber according to the level of defects specified in the grading rules. It is theoretically possible to use different classification procedures. Any process can be used as long as the determination is correct.

Note 1: Class classification rules often include rules to ensure adequate utility characteristics.

Note 2: National grading standards or rules include grading processes that are generally consistent with the objectives of this standard.

- Regarding classification parameters

+ Basic regulations serving the grading of non-structural wood must be consistent and recognized through the different characteristics of species, quality of logs, production conditions, and potential uses of the product.

+ The grading rule must define a maximum percentage below grade as the allowable deviation between graders when grading. Grading non-structural Timber is not considered an exact science because it is based on the visual inspection of each sample or on the judgment of the grader.

Note: The maximum percentage specified below grade is determined by national grading standards or rules; Normally, the allowable deviation is from 5% to 10%.

- Regarding minimum class requirements

+ The method of determining the range and limiting the characteristics to the worst acceptable samples within each wood grade is specified in the grading rules, except at the lowest grade of each grade. Because there is a wide variety of grades of non-structural timber produced, overlap of grades and patterns is selected from one grade to another grade outside that grade.

+ A specific lot will be formed, not only from products with the same characteristics or dimensions allowed in the class.

- Characteristics of the grades

+ Acceptable properties and limits for standard non-structural timber must be similar to those described in the grading rules for surface-finished lumber of a similar grade, in addition, it is allowed to omit some features when performing standard machining.

+ If there are any characteristics that differ from the description in the published ranking criteria, they should be evaluated in relation to the allowed or limited characteristics described for the ranking. They should be considered and accepted if they are considered equivalent or have little impact on the appearance or other utility value of the sample.

+ In all classes, the scale of allowable characteristics must not exceed the provisions in the corresponding classification rules.

Note: For many classes, the scale of the acceptance characteristics varies in proportion to the surface dimensions or cross-sectional area of the sample. In wood classification according to the "section system," the corresponding classes often provide the maximum acceptable size for splits, knots, hollows, shells, etc., when necessary.

- Special regulations

The classification of core wood, sapwood, and grain direction, when additional regulations are prescribed, must comply with the requirements of the specific regulations as well as the regular grades specified. Timber that meets these criteria is considered to be of standard quality.

- Non-standard grades

Non-standard grades are assigned for non-standard grades, sizes, or types according to regulations, or when there are specific regulations that allow for the bypassing or alteration of standard grades. The grading will be conducted accordingly, but all other regulations of the grading criteria must still be applied.

More details can be found in TCVN 10573:2014.

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