Joint design and joint groups

For the purpose of joint design, all species have been classified into six joint groups:

• J1 to J6 for the unseasoned condition and

• JD1 to JD6 for the seasoned condition.

Where test data is not available for a particular species, a joint group may be established from the average species density. Table 1 below provides minimum average densities for each joint group.

Note: Basic density is the mass of an oven-dry specimen divided by its volume when unseasoned.

Reference: NAFI Timber Manual: Timber Datafile P1 – Timber Species and Properties.

Table 1. Timber Density/Joint Group Relationship