A carpenter is installing floor joists specified on a building blueprint as nominal 2\time… — Armed Services Vocational Aptitude Battery (ASVAB)

A carpenter is installing floor joists specified on a building blueprint as nominal $2\times 8$ dimensional lumber. What are the actual surfaced ( $\text{S4S}$ ) cross-sectional dimensions of each joist?

A
$1\frac{1}{2}\text{ inches} \times 7\frac{1}{2}\text{ inches}$
$1\frac{1}{2}\text{ inches} \times 7\frac{1}{4}\text{ inches}$ Answer
C
$2\text{ inches} \times 8\text{ inches}$
D
$1\frac{3}{4}\text{ inches} \times 7\frac{1}{2}\text{ inches}$

Answer

The actual surfaced dimensions of a nominal

2\times 8

lumber joist are

1\frac{1}{2}\text{ inches} \times 7\frac{1}{4}\text{ inches}

In standard construction lumber grading, nominal sizes refer to the rough-cut lumber before drying and planing. Surfaced four sides (

\text{S4S}

) lumber is smaller: nominal

2\text{-inch}

thickness is reduced by

1/2\text{ inch}

1\frac{1}{2}\text{ inches}

, while nominal widths of

8\text{ inches}

and greater are reduced by

3/4\text{ inch}

, resulting in an actual width of

7\frac{1}{4}\text{ inches}

Step-by-Step Solution

Determine the actual finished thickness for nominal

2\text{-inch}

lumber.

Actual thickness is

1\frac{1}{2}\text{ inches}

Standard surfaced dimensional lumber with a nominal thickness of

2\text{ inches}

is planed down by

1/2\text{ inch}

Determine the actual finished width for nominal

8\text{-inch}

lumber.

Actual width is

7\frac{1}{4}\text{ inches}

For lumber widths of

8\text{ inches}

and wider (such as

8

10

, and

12\text{ inches}

), standard surfacing deducts

3/4\text{ inch}

rather than

1/2\text{ inch}

Key Concept

Nominal versus actual surfaced dimensions of dimensional framing lumber

Estimated Time:1m 0s

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