Lumber is the heart of your shed.
Even the best shed plan can go to waste if you don't use the
right lumber. This article is intended to give you a brief
overview of how to choose the right lumber for your shed, so
that you can build a shed that will last a lifetime.
Before you leave, be sure to check out our
Complete Shed Plans or
Gazebo Plans Package and you will hopefully see how we have
the best shed plans on the market.
Choosing the Right Lumber
for your Shed
The illustration below will give you an idea of some of the
defects found in dimensional lumber. Typical defects are
checks that result from the separation of wood across
annual rings, knots that result from a portion of a tree
branch incorporated in cut lumber, and splits which are a
separation of the wood due to tearing apart of the wood cells.
A shake is a lengthwise separation of the wood which
usually occurs between the rings of annual growth. None of
these defects should cause you to reject lumber outright.
However, wood with a bow, cup, crook,
wane, split, or twist should be avoided in
Dimensional lumber is typically
sold in incremental lengths of 2 feet. For example, 2x6
lumber comes in 8, 10, 12, 14, 16, and 20 feet. When you
plan your shed, you should try to consider standard board
lengths in the overall dimensions of your shed. A 12' x
16' shed will be far more economical to build than a shed
measuring 11' x 19' due to waste.
Standard Dimensions of
Surfaced (actual) size
|1 x 2
3/4" x 1-1/2"
|1 x 3
3/4" x 2-1/2"
|1 x 4
3/4" x 3-1/2"
|1 x 6
3/4" x 5-1/2"
|1 x 8
3/4" x 7-1/4"
|1 x 10
3/4" x 9-1/4"
|1 x 12
3/4" x 11-1/4"
|2 x 3
1-1/2" x 2-1/2"
|2 x 4
1-1/2" x 3-1/2"
| 2 x
1-1/2" x 5-1/2"
|2 x 8
1-1/2" x 7-1/4"
|2 x 10
1-1/2" x 9-1/4"
|2 x 12
1-1/2" x 11-1/4"
|4 x 4
3-1/2" x 3-1/2"
|4 x 10
3-1/2" x 9-1/4"
|6 x 8
5-1/2" x 7-1/2"
For example, a 2x6
board measures approximately 1-1/2" x 5-1/2" depending upon
moisture content and surface. Lumber that has a rough
surface will measure close to the nominal size in comparison
to lumber that is surfaced on four sides (known as S4S).
The most critical factor in determining the actual sizes of
dimensional lumber is the moisture content of the wood.
Look for the grade stamp imprinted on the lumber to
determine the moisture content. Typical moisture
content ratings are:
MC 15 (less than 15% moisture content)
S-DRY (less than 19% moisture content)
S-GRN (greater than 19% moisture content)
A 2x6 surface unseasoned board (S-GRN) will actually measure
1-9/16" x 5-5/8" compared to 1-1/2" x 5-1/2" for a 2x6 rated
surfaced dry (S-DRY). The chart above shows actual
versus nominal sizes of dimensioned lumber which is S4S and
S-DRY or better. Avoid unseasoned lumber especially in
framing your shed. Lumber which is unseasoned can
shrink considerably as it dries naturally and is certain to
cause structural problems as your shed ages.
Choosing the correct lumber for your shed can be as
consequential as determining the correct design. For
use in a shed, the lumber you select must perform well in an
exposed outdoor environment. Performance is measured
according to the following criteria:
Freedom from Shrinkage and Warping.
Lumber which has dimensional stability will not cause
problems in your shed later.
Decay Resistance. Generally lumber cut
from heartwood (center of the log) is more resistant to
decay than lumber cut from sapwood (outside of the log).
However, chemical pressure treatment can provide decay
resistance to species which lack this property.
Workability. Refers to the ease with
which you can saw, nail, or shape lumber.
Nail Holding. Determines whether or not
a given species possesses good nail holding power.
Paint Holding. The ability to hold a
finish. Some species which contain high levels of
natural extractives (such as pitch or resins) do not hold a
Fire Resistance. All woods are
combustible, but some do resist fires better than others.
Woods which do not contain large amounts of resin are
relatively slow to ignite.
Strength and Weight.
Wood which is relatively light in weight but
possesses great strength is ideal.
While no single species performs ideally according to all of
the criteria above, your local lumber dealer will be able to
advise you regarding the lumber species most suited to your
area. Often you must balance consideration of economy
with performance. For example, redwood is considered a
premium construction material, but high transportation costs
outside the area of manufacture make pressure treated pine
woods a more economical alternative.
Here is a concise guide to some common softwood species used
in shed construction:
Cedar, Western Red. Popular for the
durability and decay resistance of its heartwood.
Cypress. Cypress resists decay, has an
attractive reddish coloration, and holds paint well.
Douglas Fir, Larch. Douglas fir has
great strength and is used best in the framing of your shed,
especially in the floor joist members.
Numerous pine species have excellent workability but are
often pressure treated for use in exterior construction.
Southern Pine. Unlike the soft pines
described above, southern pines possess strength but are
only moderately decay and warp resistant.
moderate strength, rests decay and warping.
A premium construction material because of its durability,
resistance to decay, and beautiful natural brownish-red
Remember that in certain circumstances you can use two
different species of lumber to construct your shed.
For example, redwood can be used for exterior trim while
douglas fir is used for strength ins the shed wall and roof
Whatever lumber species you select, it is important to learn
the difference between the grain patterns in dimensional
lumber. Flat grain lumber is cut with the grain
parallel to the face of the board. Typically used for
decking, flat grain boards should be used with the bark side
up in order to minimize cupping and grain separation.
Vertical grain lumber, a more expensive grade used for
finish work, is cut with the grain perpendicular to the face
of the board.
Due to recent developments in timber cutting practices and
the reduced availability of certain sizes of framing lumber,
engineering lumber manufactured from plywood, wood chips,
and special glue resins offers and attractive alternative to
dimensional lumber used for joists, beams, headers, and
rafters, for your shed. Unlike sawn dimensional
lumber, engineered lumber is a manufactured product that
will not warp and shrink over time.
Engineered lumber is manufactured to meet stringent criteria
for strength, uniformity, and reliability. Glu-lam
beams offer great strength over spans. Wood I-beams
provide a lightweight alternatives to conventional rafters.
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