H level 5. The minimum level of preservative treatment required to protect the timber situations where timber is in contact with the ground or fresh water. !!Must be treatable commercially to H5 level.

Timbers allocated H5 (Hazard level 5) can only be used in the specified application if that timber can be commercially treated to a minimum H5 level.

N.B. Currently, the heartwood of most hardwood timbers and some softwood timbers cannot be treated to this level of protection. The timber treater is to ensure that their process has achieved the required level of penetration to meet the stated H level specification.

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