Installing Redwood Siding Tutorial, Woodworking Tips, Guides, Articles, Magazines, Texts, etc
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Certified Kiln Dried
Siding Patterns and
Applications
Dimensional Stability Test reports from
the USDA Forest Products Laboratory
show that redwood has less volumetric
and tangential shrinkage than any other
domestic softwood. This means that
redwood siding will lay flat and straight
throughout the life of the structure with
minimal warping, cupping, checking and
nail popping. With tighter joints, redwood
provides better siding performance
than other woods.
Finish Retention
Redwood has an open cellular structure
and contains relatively little pitch or
resins. This enables redwood to absorb
and retain all types of finishes better than
most other woods. As a result, projects
look better over a longer period of time.
Protective finishes last longer and work
better. Refinishing is required less often.
Resistance to Decay and Insects
Redwood heartwood has grown-in
resistance to decay and insects that is
present throughout the lumber, not just
on the surface. Wood exposed through
sawing, boring or nailing is as decay-
resistant as the surface.
The CRA trademark is on products of
member mills of the California Redwood
Association only and is an additional
assurance of quality.
Redwood grades are established by the
Redwood Inspection Service in the
Standard Specifications for Grades of
California Redwood Lumber. Properly
grademarked lumber will bear the RIS
mark. The RIS is the exclusive rules-
writing agency for redwood lumber.
Quality redwood siding is available in
the architectural grades: Clear All Heart,
Clear, Heart B and B Grade.
Clear All Heart
is a superior grade for
fine sidings and architectural uses. It is
all heartwood and the graded face of
each piece is free of knots.
Clear
is similar in quality to Clear All
Heart, except that it includes sapwood
in varying amounts. Some boards may
have one or two small, tight knots on
the graded face.
Heart B
is an economical all-heartwood
grade containing a limited number of
tight knots and characteristics not
permitted in Clear or Clear All Heart. It
is graded on one face and one edge.
B Grade
is an economical grade con-
taining a limited number of tight knots
with sapwood accenting the heartwood.
Redwood is synonymous with quality
architecture. No other siding material
adds value to a home or commercial
building like redwood. The value of
redwood’s beauty is immediately appar-
ent and the value of its long-lasting
performance is appreciated for decades.
Architects and builders specify redwood
with confidence, knowing that exceptional
performance is grown into every board
and that redwood will add value and
sales appeal to their projects.
Redwood’s Total Performance
Redwood’s performance characteristics
are unique among American softwoods.
Its superior stability is especially suited to
the demands of siding applications. Its
finish retention, weatherability, flame
resistance and insulation properties
make it ideal for virtually any project and
even the most extreme climate.
Specifying
Storage & Handling
Specifying Redwood Siding
To ensure delivery of the proper siding
product, the specifications should
include: use, grade, grain, seasoning,
pattern description and number, and
surface texture.
For Example
Redwood lumber for
1
exterior siding
shall
be CRA-RIS grademarked redwood,
2
Heart B
grade,
3
mixed grain.
4
Certified
Kiln Dried,
5
1x8 channel V shiplap,
6
pattern 785R,
7
saw-textured
face to
be exposed.
1
Use
Application
General Application Information
Careful attention to construction detailing
is necessary to prevent moisture pene-
tration into the siding and the wall cavity.
Flashing over window and door headers
and at other horizontal siding breaks
should be sufficiently sized, well placed,
tightly anchored and sealed with caulk-
ing. Thorough caulking of all joints with a
non-hardening compound is important,
particularly at the butt joints of short
length siding laid vertically. High per-
formance caulks such as polyurethane,
polysulfide or acrylic latex are recom-
mended for best results.
The lowest edge of siding should be at
least 6 inches off the ground to prevent
moisture problems. It is particularly
important that end grain at the bottom
of vertical siding be coated with water
repellent. The use of a drip cap at the
lower edge of the siding is recommended.
A water repellent building paper, with a
permeability rating of at least 5 perms,
should be applied over sheathing. This will
help reduce water and wind penetration.
Note:
There have been reports of prob-
lems arising from the combination of
wood siding and rigid plastic foam
sheathings. CRA advises caution.
Request Redwood Technical Data Sheet
Using Redwood Siding Over Rigid
Foam Sheathing.
Grain
Redwood lumber has either flat or vertical
grain. Siding Is considered vertical grain
when the annual growth rings form an
angle of 45 degrees or more with the
surface of the siding. If the angle is less
than 45 degrees, the siding is known
as flat grain. Vertical grain siding pos-
sesses enhanced dimensional stability
and will hold paints and finishes better
than flat grain.
Vertical Grain
5
Pattern
2
Grade
6
Pattern Number
3
Grain
7
Texture
Flat Grain
4
Seasoning
In addition, the Installation section of the
specification should specify: non-corro-
sive fastener materials, type and size;
bearing and fastener spacing require-
ments; water repellent application as ap-
propriate, and field priming of cut edges.
Storage and Handling
Redwood siding and trim are quality
finish products and should be handled
with care. At the job site, redwood siding
should be kept completely under cover
and off the ground. Water-proof cover-
ings should allow air to circulate between
the covering and the siding. Keeping the
siding clean and dry will help to eliminate
the possibility of finish problems. For
protection, redwood siding is now avail-
able wrapped in moisture-proof paper at
the sawmill and it should not be un-
wrapped until installation begins.
Priming
It is recommended that a water repellent
containing mildewcide be applied to all
surfaces of redwood siding before
construction begins. This will inhibit the
movement of moisture as well as mildew
growth, two conditions which can
severely damage a finish coating. When
a clear, bleached or semitransparent
finish is to be applied later, a preliminary
coat of water repellent will protect
against weathering and construction
staining prior to final finishing. For best
performance, special care should be
given to end grain; cut ends should be
coated before installation. Redwood
siding should always be back-primed.
Factory priming or pre-finishing is
highly recommended.
Annual rings
Bark side
Pith side
Seasoning
Clear All Heart, Clear, Heart B and B
Grade sidings are available Certified Kiln
Dried for applications requiring minimal
shrinkage and top performance.
Redwood kiln dried to accepted stan-
dards will include the words “Certified
Kiln Dried” or the initials “CKD” in the
grademark on each piece or package of
siding or be so specified on the invoice.
Patterns
Standard redwood siding patterns
include: bevel, rabbeted bevel, tongue
and groove, shiplap, channel shiplap and
V shiplap. Board and batten siding is
laid up using standard size boards.
Pattern Numbers
Each siding pattern has a pattern num-
ber. To ensure delivery of the proper
product, the pattern number should be
included on specifications and invoices.
Pattern details are given in CRA’s
Architectural Guideand Redwood
Pattern Book.
Textures
Surfaced sidings have a smooth, planed
face, emphasizing the wood’s grain
and color.
Saw-textured sidings have resawn faces
providing a rough textured appearance
that holds finishes extremely well.
Measuring and Cutting
All butt joints must occur over a stud or
solid blocking. Be sure that siding fits
snugly against corner strips and trim.
Mitered corners, sometimes used with
thicker patterns, should be cut in a miter
box. Plain bevel siding requires a com-
pound miter. Predrill nail holes for all
ends, especially mitered ends.
Using bevel cuts at a 45° angle (see
illustration) can minimize the appearance
of gaps if end shrinkage does occur.
Preventing Moisture Problems
causes of structural and finish failures. It
moves as invisible moisture vapor from
the warm interior of the house toward the
cold exterior. Vapor travels through
plaster, insulation and wood and may
condense into water as it approaches the
colder exterior surfaces of the sidewall.
This can sometimes result in structural
damage as well as siding cupping and
nail popping. Water entering the siding
can also cause finishes to blister, peel
and discolor.
Vapor barriers are necessary to prevent
migration of moisture vapor. They must
be applied to the warm side of the stud
wall, directly under the finish material.
There are several types; the most fre-
quently used are either plastic or alu-
minum sheet material with a rating of
one perm or less. Those sheets should
overlap at least 2 inches at their edges.
Ordinary building felt is not a vapor barrier.
When residing an existing house without
a vapor barrier, an effective solution can
be to paint the inner side of the exterior
walls with a vapor barrier paint.
Attic areas should be adequately vented
to prevent vapor from condensing on
cold surfaces or penetrating through the
ceiling. Critical sources of humidity, such
as kitchens, baths and laundries, are
best ventilated by fans that exhaust out-
doors. Crawl spaces should be well
ventilated all around the house; the vent
area should equal about 1/50th of total
floor space. Keep vents free of obstruc-
tions. Movement of vapor into stud
spaces from crawl spaces may take
place as water evaporates from the
ground under the house, and can be
retarded by laying polyethylene film
over the ground. Basements may be a
source of considerable dampness and
require effective ventilation.
Stop Moisture
From Outside
Stop
Moisture
Vapor From
Inside
Siding
Finished
On All
Surfaces
Wallboard
Vapor Barrier
Insulation
Bevel Cut
Siding
Sheathing
Building
Paper
Sheathing
Stud
Do not reduce CRA lap recommenda-
tions as this can result in damage from
wind-driven water. Carefully observe
expansion clearance requirements for
the siding pattern selected.
Nailing
Nailing recommendations refer to nailing
siding to every stud or (for vertical cours-
ing) each 2x4 blocking line, at not more
than 24 inches on center.
Selection of proper nails is important.
Siding nails with annular-ringed shanks
provide the best holding power. All nails
must be either stainless steel, aluminum
or top-quality, domestic, hot-dipped gal-
vanized. Electroplated galvanized nails
are not recommended. Poor quality
nails will react with redwood’s natural
decay-resisting extractives, and will cause
unsightly stains.
Nails can be countersunk (not more than
1/16 inch) or driven flush with wood sur-
faces. Unfilled nail holes may not be par-
ticularly noticeable where natural finishes
are used as long as proper quality nails
have been used. At mitered corners, or
near the edge or end of a piece, pre-drill
the nail hole to avoid splitting the wood.
Nails must be long enough to penetrate
into studs (or stud and wood sheathing
combined) at least 1-1/2 inches. Do not
fasten siding to only composition or
pressed fiber sheathing as those materi-
als provide no nail-holding power.
Do not use staples for redwood siding.
Staples do not provide adequate
holding power and most are not
corrosion-resistant.
Proper interior and exterior wall construction
prevents moisture problems. Building paper
should have a permeability rating of 5 perms,
the vapor barrier, a maximum of 1 perm.
Moisture is the largest cause of siding
and finish problems. Most problems can
be avoided if precautions are taken
during construction. Understanding the
dynamics of wood’s reaction with mois-
ture will be the builder’s best protection
against callbacks.
New energy-efficient construction tech-
niques increase the amount of humidity
within homes and commercial buildings.
Efficient insulation, storm windows,
weatherstripping, as well as heating
equipment and appliances that retain
warmth add to the build-up of interior
moisture vapor.
This invisible moisture is one of the least
understood and most troublesome
Bevel & Rabbeted
Bevel Patterns
Plain Bevel
Horizontal Siding (Side View)
Rabbeted Bevel
Horizontal Siding (Side View)
Overlap
undercourse
by 1''
Redwood bevel siding, also known as lap
or clapboard siding, has the timeless
appeal of a strong traditional style and
provides the deepest horizontal shadow
line of all siding patterns.
Bevel siding is produced in both plain
and rabbeted patterns. Each is available
in two different butt thicknesses for
variation in depth of shadow line and
insulation value.
Plain bevel patterns produce a bolder
shadow line than rabbeted bevel pat-
terns of the same thickness. Rabbeted
bevel, with its 1/2-inch rabbet milled
to fit over the thin edge of the preced-
ing course, allows the siding to lay
flat against the studs or sheathing.
Rabbeted patterns provide a weather-
tight lap and lay up with greater coverage
than plain patterns.
Availability
Bevel and rabbeted bevel sidings are
available in all architectural grades.
Plain bevel siding has a smooth surface
on one face and a saw-textured surface
on the other face. Either face may be
exposed. Rabbeted bevel siding is
available with either a smooth or saw-
textured face. Saw-textured faces are
more even in color and appearance and
they hold finishes better.
Installation
With plain bevel patterns, use a furring
strip to support the lower edge of the
starting course. With rabbeted patterns,
the bottom course should be supported
by a nailing strip sawn from the thin
Stud
1⁄8''
expansion
clearance
Sheathing
Stud
Beware of
driving nail
home with
too heavy
a final blow.
Wood may
split due to
non-support
in cavity.
Sheathing
Nail must
penetrate
solid wood
1-1⁄2''
Nail clears tip
of undercourse
Nail must
penetrate
solid wood 1-1⁄2''
Face nail with one nail only per bearing.
Drive nail so shank just clears the tip of the
preceding undercourse. The space between
the nail shank and the tip of the preceding
course should not exceed 1/8 inch.
Face nail with one nail only per bearing.
Position material to allow expansion
clearance of 1/8 inch. Drive nail about one
inch above lower edge of course.
edge of the pattern. Nail bevel siding at
every stud, which should not exceed 24
inches on center.
For plain bevel siding, a lap of one inch is
required to ensure weather-tightness.
Note:
With CKD rabbeted bevel patterns,
an expansion clearance of 1/8 inch is
required in the rabbet.
Sample Specification
Exterior siding shall be CRA-RIS grade-
marked redwood Clear grade, mixed
grain, Certified Kiln Dried, 3/4x8
Rabbeted Bevel, pattern 372, with a
saw-textured face.
Surface Feet of Bevel Siding to Cover
1 Square (100 sq. ft.)
Nominal
Width
Plain
Rabbeted
4 inch
160
128
5 inch
143
6 inch
134
117
8 inch
124
117
10 inch
122
113
Size Availability
Bevel & Rabbeted Bevel
Bevel
4''
5''
6''
8'' 10''
1/2 inch
•
•
•
•
3/4 inch
•
•
•
Rabbeted Bevel S1S-2E smooth
4''
5''
6''
8'' 10''
1/2 inch
•
•
•
3/4 inch
•
•
•
Rabbeted Bevel S1S-2E saw-textured
4''
5''
6''
8'' 10''
3/4 inch
•
•
•
Tongue & Groove
Tongue and Groove
Horizontal Siding (Side View)
Tongue and Groove
Horizontal Siding (Side View)
Redwood tongue and groove siding is
versatile and weathertight. Its variety
of refined patterns has established a
permanent place in residential and
commercial architecture. Tongue and
groove siding can be laid up vertically,
horizontally or diagonally and is ideal for
matched interior-exterior combinations.
Tongue and groove patterns are pro-
duced in square edge, eased (slightly
rounded) edge and various widths of
V groove edges. The latter create a
shadow line emphasizing the direction
of the courses. Various design effects
are achievable by alternating patterns
and board widths.
Availability
Tongue and groove sidings are available
in all architectural grades.
Standard tongue and groove patterns
come from the mill with a smooth surface
on both faces. Reversible patterns are
saw-textured on one face and surfaced
smooth on the other. All tongue and
groove siding patterns can be special
ordered saw-textured. Saw-textured
faces are more even in color and
appearance and they hold finishes better.
Tongue and groove redwood is also
available in thinner patterns commonly
used for interior paneling.
Installation
Tongue and groove siding is properly
applied with the groove edge down; this
assures a weathertight wall.
Horizontally-applied tongue and groove
siding should be nailed at every stud,
not exceeding 24 inches on center.
Siding applied vertically should be nailed
to 2x4 horizontal blocking that is
Stud
Sheathing
Stud
Sheathing
Blind nailed
Nail must
penetrate
solid wood
1-1/2''
Nail must
penetrate
solid wood
1-1/2''
For 4-and 6-inch widths of tongue and groove
siding over solid wood sheathing, blind nailing
is possible using one 8-penny finishing nail
per bearing.
Tongue and groove siding 8 inches or wider
should be face-nailed, using two 8-penny
nails per bearing.
installed between the studs at not more
than 24 inches on center. As an alterna-
tive, vertical siding may be nailed to 1x3
furring strips and solid wood sheathing at
24 inches on center.
Sample Specification
Exterior siding shall be CRA-RIS grade-
marked redwood Clear grade, vertical
grain, Certified Kiln Dried, 1x8 Tongue
and Groove, pattern 712R, saw-textured
face to be exposed.
Surface Feet of Tongue & Groove
Siding to Cover 1 Square (100 sq. ft.)
Nominal Width
Coverage Factor
4 inch
128
6 inch
118
8 inch
117
10 inch
113
Size Availability
Tongue & Groove
Eased Edge S2S-CM
4''
6''
8''
10''
1 inch
•
•
•
V1S S2S
4''
6''
8''
10''
1 inch
•
•
•
•
V2S-S1S Saw Textured 1S
4''
6''
8''
10''
1 inch
•
•
•
•
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