A Water-Management-First Guide to Installing Cedar on Walls

Applying cedar siding correctly is not a matter of choosing one overlap and one nail pattern. Installation changes with the profile, width, grade, moisture condition, orientation, substrate, finish system, wall assembly, and exposure.

This guide is a profile-selection and general sequencing reference, not a complete wall design or engineering specification. Start by identifying the exact product. Then establish how the wall will shed bulk water, drain incidental moisture, accommodate wood movement, and provide approved fastening support. Only after those decisions are settled should you lay out courses, keyways, overlaps, joints, and fastener locations.

This is a sidewall guide, not a cedar-roofing guide. Do not transfer roofing exposure, underlayment, ventilation, or fastening details to a vertical wall merely because both systems use cedar shingles or shakes.

Identify the Cedar Profile Before Choosing Any Dimensions

The term cedar siding covers several materially different systems:

• Bevel siding, also called clapboards, uses tapered horizontal boards that overlap.
• Wall shingles or shakes use individual pieces arranged in courses with side joints or keyways.
• Tongue-and-groove siding has interlocking edges and may be installed horizontally or vertically.
• Lap or channel siding uses a milled overlap or channel rather than bevel-board geometry.
• Board-and-batten siding uses wider vertical boards with narrower battens covering the spaces between them.

Starter details, orientation, overlap or keyway spacing, expansion allowance, fastening pattern, and joint treatment differ among these profiles. Roof-shingle exposure tables do not govern wall shingles. Even among sidewall products, grade, treatment, length, moisture condition, and single- or double-coursing can change the applicable schedule.

Before buying fasteners or marking layout lines, record:

1. Manufacturer or supplier
2. Cedar species
3. Product name and profile
4. Grade and treatment, if any
5. Nominal width and measured actual dimensions
6. Delivered moisture condition
7. Intended horizontal or vertical orientation
8. Factory-applied, field-applied, or unfinished finish system
9. Approved substrate and wall assembly
10. Product-specific overlap, exposure, gap, and fastening schedule

These details determine whether the siding is face-nailed or blind-nailed, where each fastener belongs, whether joints remain open, and how movement is accommodated. The current instructions for the selected product and applicable local requirements take precedence over this general reference.

Every entry in this table is general rather than universal. Use it to choose the correct installation path, not as a substitute for the selected product manual.

Prepare the Cedar, Wall and Water-Management Plan

Do not open bundles and begin fastening while the supporting wall and water-management details remain unresolved. Preparation must establish both an approved attachment path and a continuous route by which incidental water can leave the assembly.

Preinstallation checklist

• Inspect the delivered siding for the specified species, profile, grade, dimensions, treatment, and finish.
• Obtain the current installation manual for the exact product.
• Verify that framing, sheathing, blocking, or furring is sound and approved for the installation.
• Repair decay, loose sheathing, damaged framing, and unacceptable surface irregularities.
• Establish the water-resistive barrier, or WRB, and flashing sequence.
• Complete compatible window, door, corner, soffit, fascia, and base trim as required.
• Identify framing, blocking, furring, or other approved solid fastening locations.
• Confirm how exterior insulation and existing wall layers affect support and fastener length.
• Lay out penetrations, fixtures, vents, and roof-wall or deck-wall intersections.
• Determine when the finish system requires primer, stain, or cut-end treatment.
• Verify project-specific requirements for exposure, attachment, and alterations to the existing wall.

Store cedar flat or on properly spaced supports. Keep it dry, covered, ventilated, and elevated above soil or concrete. The cover should protect the material without trapping moisture. Acclimate the siding under the conditions and for the period specified by its manufacturer; leaving it outside for an arbitrary number of days is not a reliable universal method.

Inspect every piece before installation. Set aside damaged, incorrectly graded, badly distorted, or finish-defective material rather than fastening it and trying to correct the problem afterward. When cutting exposes fresh end grain, apply the primer or stain prescribed by the selected finish system before the cut becomes inaccessible.

Finishing instructions are not interchangeable. One system may call for coating several faces before installation, while another may address only exposed surfaces and fresh cuts. Follow the applicable coating instructions for wood condition, preparation, coverage, and drying rather than combining recommendations from unrelated products.

Settle the wall assembly—not merely the siding profile

A cedar profile does not define the complete WRB, rainscreen, penetration-flashing, or attachment design. The appropriate assembly depends on the selected siding, sheathing, exterior insulation, flashing products, climate, exposure, and applicable requirements. Some assemblies use a drainage-capable WRB behind the siding; others incorporate furring or another drainage and ventilation layer.

Shingle instructions may differ from those for board siding. For example, the Cedar Shake & Shingle Bureau recommends specified roofing felt rather than housewrap behind the cedar shingle sidewalls covered by its guidance. That is a shingle-system recommendation, not permission to use roofing felt behind every cedar profile (CSSB installation FAQ).

Before installation, draw a layer-by-layer wall section showing:

• Interior-to-exterior wall layers
• Approved WRB or sidewall underlayment
• Drainage or ventilation space, when specified
• Furring orientation and thickness
• Window and door flashing integration
• Base drainage and insect-screen details
• Roof-wall, deck-wall, and material-transition flashing
• Cedar profile and orientation
• Fastener path into the approved substrate

Do not assume that ordinary sheathing alone provides adequate attachment. Sheathing type and thickness, framing location, blocking, furring, insulation, fastener length, required penetration, wind exposure, and product approval must be considered together. If those requirements are not stated in the siding instructions, obtain a project-specific specification before proceeding.

Overlaying existing siding

Installing new cedar over old cladding is not automatically acceptable. First verify:

• The type and condition of the existing cladding
• Whether the old wall is flat, dry, secure, and free of concealed deterioration
• Whether the sheathing and framing remain sound
• Whether the existing WRB is continuous and serviceable
• How new flashing will integrate with windows, doors, penetrations, and the wall base
• Whether furring can be attached to approved support
• How added thickness affects jambs, sills, head flashing, corners, soffits, and utility fixtures

An archived Green Building Advisor discussion illustrates why overlay work is project-specific: attachment through an older layered wall was considered conditionally possible, but the answer depended on sheathing, fasteners, stud locations, and a deliberate WRB and window-flashing strategy—not a blanket overlay rule (Green Building Advisor discussion).

Safety when handling and machining cedar

• Wear gloves suited to rough or splinter-prone material.
• Use eye protection while cutting, drilling, or fastening.
• Collect dust at the tool and ventilate the work area.
• Select respiratory protection appropriate to the task and exposure.
• Keep wood dust away from sparks, flames, and other ignition sources.
• Follow the operating instructions for saws, nailers, compressors, ladders, and scaffolds.
• Keep guards installed and support workpieces before cutting.

Cedar machining can create combustible dust and can irritate the skin, eyes, lungs, and respiratory tract, making dust control and suitable personal protection part of the installation plan (cedar-shingle handling and installation guidance).

Install Flashing and Preserve Drainage Before Siding

Install flashing before the cedar it protects. Flashing intercepts water moving down the face of the wall or behind the siding and directs it back outside. Sealant cannot reliably replace a shaped, lapped drainage component.

Install horizontal flashing where applicable, including:

• Above windows and doors
• Above bandboards and water tables
• At horizontal trim interruptions
• At changes in cladding material
• At changes in material direction
• Where a wall meets a roof or deck
• At other interruptions where water must be projected outward

Complex sill, jamb, penetration, deck-ledger, and roof-wall details require the instructions for the applicable window, WRB, flashing, roofing, and siding products. Arrange the layers in drainage order so downward-moving water does not encounter a reverse lap.

Slope flashing outward. Western Red Cedar guidance calls for holding siding or trim 1/4 inch above a flashing ledge. It also gives general minimum clearances of 2 inches above roofs and decks and 6 inches above grade for water-table or skirt-board trim, subject to stricter product or local requirements (Real Cedar general installation guidance).

These measurements do not supersede a profile-specific drawing. A shingle base detail may prescribe another distance above bottom flashing, while snow, splashback, adjoining-product warranties, or project requirements may call for greater clearance.

Flash, caulk, seal, or leave open?

Caulk is not a substitute for head flashing, step flashing, sill drainage, or proper WRB integration. It can worsen a defect if it blocks the lower edge through which water is intended to escape.

For Western Red Cedar, industry guidance lists high-performance acrylic-latex, acrylic, acrylic-silicone, polyurethane, polysulfide, and terpolymer-rubber sealants while discouraging pure silicone and clear caulks. Compatibility must still be confirmed with the selected finish, flashing, trim, joint geometry, and sealant instructions.

Before covering flashing, establish a visual hold point. Confirm outward slope, correct laps, required end dams, WRB integration, and an unobstructed outlet. Photograph details that will become concealed.

Choose Cedar-Compatible Fasteners and Set Them Correctly

Fastener selection involves two separate questions:

1. Is the metal compatible with cedar, treatment, adjoining metals, and the exposure?
2. Does the fastener provide the required attachment through every intervening wall layer?

Corrosion resistance does not compensate for inadequate length, incorrect placement, unsupported ends, or overdriven heads.

Western Red Cedar supplier guidance accepts stainless-steel, hot-dipped galvanized, and aluminum nails while excluding electroplated fasteners and copper. It describes stainless steel as the preferred selection and hot-dipped galvanized as a common economical option (FP Cedar Supply installation guidance). These are material-specific supplier recommendations; the selected siding manual remains controlling.

For cedar shakes and shingles, CSSB guidance requires Type 316 stainless steel within 15 miles of salt water and for treated cedar products. Outside those conditions, the permitted alternatives depend on the product and application (CSSB installation FAQ).

Specify the complete fastener

Confirm all of the following:

• Nail, staple, screw, or proprietary fastener type
• Material and corrosion-resistance grade
• Shank style and diameter
• Head type and diameter
• Overall length
• Required penetration or embedment
• Spacing along supports
• Edge and end distances
• Face-nailing or blind-nailing location
• Whether pneumatic installation is approved
• Adjustments for furring, existing layers, or exterior insulation
• Requirements for the project’s wind exposure

Do not rely on a universal finish-nail gauge or compressor setting. A fastener suitable for a thin shingle may be wrong for a wide board, and a length suitable over one substrate may be inadequate after insulation or furring is added.

Set heads flush with the cedar unless the product specifies otherwise. Do not bury the head into the wood, and do not leave it proud enough to interfere with the next course. On shingles and shakes, nails or staples must not remain visible in joints or keyways.

Keep profile-specific penetration rules separate. The cited Western Red Cedar bevel method requires at least 1-1/4 inches of penetration into solid wood. Shingle instructions may instead describe penetration into or through approved sheathing. These requirements apply to different systems and should not be combined into one universal rule.

Apply Western Red Cedar Bevel Siding

Bevel siding is installed from the bottom upward, but the course layout should be planned before the first board is fastened.

1. Lay out the courses

Measure between the lowest planned course and the soffit termination. Mark windows, doors, bandboards, and other interruptions. Divide the available height into courses that comply with the permitted overlap and exposure.

The objective is to avoid discovering a narrow strip above an opening or an awkward final course at the soffit. Where practical, coordinate the bottom edge of the course above a window with the head flashing or cap, but do not sacrifice flashing clearance or required overlap for visual alignment.

Use a story pole or repeated layout marks at corners and openings. Transfer course lines around the building so adjoining walls and trim features remain coordinated.

2. Support the first course

Begin at the bottom. Install the prescribed furring or starter strip behind the lower edge so the first board sits at the same angle as the courses above it.

Make sure the starter does not block the wall’s bottom drainage path. Establish the first course from a verified level line rather than assuming the foundation, deck, or skirt board is level.

3. Establish the correct overlap

The Western Red Cedar bevel schedule calls for at least 1 inch of overlap, with the permitted range changing by nominal board width:

The same guidance recommends selecting a larger overlap within the applicable range for unseasoned siding to account for shrinkage and expansion. This is not a universal moisture-content formula. Rabbeted bevel patterns are self-spacing, but the cited instructions still call for 1/8 inch of expansion clearance (Real Cedar bevel installation instructions).

Do not apply a broad 1-1/4-inch minimum overlap to every bevel board. That recommendation conflicts with the stronger width-specific schedule, which starts at 1 inch for nominal 4- and 6-inch boards.

4. Fasten without pinning two courses together

For the cited Western Red Cedar bevel system:

• Use one face nail per board at each required support.
• Space fasteners no more than 24 inches on center.
• Drive into studs or other approved solid support.
• Achieve at least 1-1/4 inches of solid-wood penetration.
• Place the nail just above the overlap.
• Do not drive the fastener through both overlapping boards.

These dimensions and nail locations are specific to the cited bevel instructions, not to every cedar profile (Real Cedar bevel installation instructions).

Use a spacer or marked gauge to keep the exposure consistent, but recheck the layout at openings. Do not allow small errors to accumulate until the final course.

5. Treat and support field joints

Stagger butt joints between courses. Place each field joint over a stud, blocking, or approved furring so both board ends are supported.

General Western Red Cedar guidance describes ends cut at 45 degrees to create an overlapping field joint. Apply the prescribed primer or stain to fresh end cuts, and use the exact joint orientation and fastening detail specified for the selected product (Western Red Cedar installation course).

Keep fasteners far enough from thin ends to avoid splitting. Predrill when required by the product instructions or when the board condition and edge distance make splitting likely.

Apply Cedar Wall Shingles or Shakes

This section concerns cedar sidewalls, not roofs. Do not import roof exposure, interlayment, or nailing rules into a wall installation.

1. Install the sidewall underlayment and base detail

Complete the approved sidewall underlayment, flashing, corner preparation, and base drainage before placing shingles. CSSB recommends specified roofing felt rather than housewrap for the cedar shingle sidewall assemblies addressed by its guidance, but that recommendation does not apply automatically to bevel, lap, tongue-and-groove, or board-and-batten siding.

Begin with a doubled starter course at the wall base. Arrange the starter pieces according to the applicable drawing so the first exposed course is supported and its joints do not align with those in the undercourse.

Establish a level butt line with a temporary straightedge, ledger, string line, or verified layout marks. Do not use an out-of-level deck or foundation as the course reference.

2. Set keyways and offset joints

Keyways are intentional joints that provide space for moisture-related movement. Inadequate spacing can cause shingles to bow or curve outward, a condition commonly called fishmouthing.

Spacing is product-specific. Examples from cited wall-shingle guidance include:

• 1/8 to 1/4 inch for one No. 1 Western Red Cedar shingle product
• 1/4 to 3/8 inch for another similarly described product
• Wider joints for some shake products

Because similarly named products can use different ranges, identify the exact grade and installation sheet rather than selecting a gap by appearance. Keep each side joint at least 1-1/2 inches from joints in adjacent courses (cedar wall-shingle installation guide).

Use approved spacers rather than estimating keyways by eye. Avoid narrow slivers at openings and corners by redistributing several pieces while maintaining the required joint offsets.

3. Establish exposure and straight courses

Use the exact sidewall exposure specified for the product, grade, and coursing method. Mark repeated course lines or use a story pole. A straightedge aligned with the butt line can support and align each course.

Check the work for level every three or four courses so gradual drift can be corrected across several courses rather than forced into one visibly tapered row.

4. Place concealed fasteners correctly

For the cited shingle instructions:

• Shingles up to 10 inches wide receive two fasteners.
• Each fastener is positioned about 3/4 inch from its side edge.
• Shingles wider than 10 inches receive two additional fasteners near the center.
• The two center fasteners are spaced about 1 inch apart.

The source places fasteners approximately 1 inch above the butt line of the next course, but other guidance uses different placement dimensions. Follow the exact product manual rather than combining the two schedules.

Fasteners must be covered by the next course and kept out of visible keyways. Set heads flush rather than overdriving them. When pneumatic fastening is permitted, test the tool on representative material and continue checking depth as shingle thickness changes.

Adapt the Method for Tongue-and-Groove, Lap and Board-and-Batten

These profiles do not inherit the bevel-siding nail line or overlap schedule. Their milled geometry and orientation govern spacing, movement, and fastening.

Horizontal tongue-and-groove

Start at the bottom with the grooves facing downward.

In the cited Western Red Cedar schedule, pieces up to 6 inches wide may be blind-nailed through the tongue where the product and climate permit. Wider pieces receive two face nails. Do not improvise blind nailing when the selected profile, exposure, or finish instructions require face fastening.

Keep the first course level and straight because every later course follows it. Seat joints consistently without striking an exposed tongue directly.

Vertical tongue-and-groove

Begin at a corner with the first board plumb. Vertical siding requires approved horizontal blocking or furring at the spacing specified for the product.

Coordinate those supports with the WRB and drainage plane. Plan the wall width before starting so the last board is not an impractical sliver. Treat cut ends and preserve the specified clearance above horizontal surfaces and flashing.

Horizontal lap or channel siding

Begin at the bottom with channels facing upward as intended by the profile. The cited Western Red Cedar schedule specifies a 1/8-inch gap between air- or kiln-dried pieces. Do not transfer that number to another moisture condition or milled profile.

Do not nail through horizontal lap overlaps. Position the fasteners as shown in the applicable profile drawing so the interlocking or overlapping portion is not pinned.

Board-and-batten

Install the vertical boards according to the specified spacing and fastening schedule, followed by the battens. For cited nominal 6-inch boards spaced 1/2 inch apart, each batten overlaps each board edge by at least 1/2 inch.

The cited fastening pattern calls for:

• One centered nail per bearing for boards up to 6 inches wide
• Two nails spaced 2-1/2 to 3 inches apart for boards 8 inches or wider

The tongue-and-groove, lap, and board-and-batten measurements above come from a Western Red Cedar installation schedule and remain profile-specific (Western Red Cedar installation course).

For vertical siding, verify that horizontal supports provide attachment without creating unintended dams behind the boards.

Finish Joints and Corners, Then Inspect the Drainage Path

Field joints, corners, and transitions are part of the drainage system, not merely cosmetic finishing work.

Support and protect field joints

Place board ends over studs, blocking, or approved furring. Do not leave field-joint ends unsupported.

Where specified, cut meeting ends at 45 degrees to form an overlapping joint and orient the overlap as shown in the applicable detail. Do not apply the angled cut automatically to products that specify another joint.

Apply the finish manufacturer’s primer or stain to newly exposed end grain. Allow it to reach the required condition before closing the joint. If the selected detail requires joint flashing or sealant, install it without blocking drainage behind the siding.

Select an outside-corner method

Common options include:

• Full-depth miters: Visually clean but demanding. Both pieces must be accurately cut through their full thickness and kept aligned as installation rises.
• Corner boards: Generally easier to execute. Coordinate their depth with the siding profile, drainage plane, flashing, and required joint treatment.
• Woven shingle corners: Appropriate for specified shingle work. Alternate the pieces around the corner according to the product drawing.

For woven shingle corners, predrill where required to reduce splitting and use compatible corrosion-resistant fasteners. Do not place exposed fasteners in keyways to force a poorly fitted corner into position.

Troubleshooting visible symptoms

CSSB specifically associates inadequate sidewall keyway spacing with fishmouthing and identifies overdriven or visible fasteners in shingle joints as installation defects.

Final field checklist

Before accepting the wall, verify that:

• Courses are straight and coordinated at openings.
• Profile-specific overlaps, exposures, and gaps are maintained.
• Shingle keyways and drainage openings remain unobstructed.
• Field joints are staggered where required and land on approved support.
• Fastener heads are flush rather than buried.
• Fasteners are not visible in shingle keyways.
• Bevel and lap overlaps have not been fastened through both pieces.
• Flashing slopes outward and remains able to drain.
• Sealant has not bridged designated flashing exits.
• Roof, deck, grade, and flashing clearances are maintained.
• Corners are secure without split thin edges.
• Fresh cuts have received the prescribed primer or stain.
• Finish damage has been repaired by the approved method.
• Debris has been removed from the bottom drainage path.

At this hold point, compare the completed work with the exact product manual: profile and grade, substrate approval, WRB or underlayment, flashing sequence, finish instructions, fastener type and schedule, overlap or keyway, and applicable local requirements.

Frequently Asked Questions

Can cedar siding be installed directly over existing siding?

Sometimes, but not merely because the old siding feels solid. Verify the condition of the existing cladding, sheathing, framing, attachment, WRB, flashing, and any concealed deterioration. Determine how the added wall thickness will affect windows, doors, corners, penetrations, soffits, and base drainage.

CSSB says new cedar shingle siding can be installed over existing cedar shingles in some circumstances, but additional window and door trim is often needed. Exterior insulation or multiple cladding layers also change the required fastener length. Do not assume old siding or sheathing alone provides adequate attachment.

Potentially hazardous existing materials warrant an appropriate professional assessment before drilling, cutting, or removal.

Should cedar siding joints and laps be caulked?

Not as a blanket practice. Do not caulk bevel laps, lap-siding overlaps, shingle keyways, flashing drainage junctions, or rainscreen outlets unless the exact system expressly requires it. These locations commonly need to move or drain.

Use compatible sealant only at vulnerable joints identified by the siding, trim, window, or flashing detail. Correct poor carpentry rather than filling unsupported or incorrectly sized gaps. Prime or stain exposed end grain as prescribed, but remember that end-grain coating and joint sealant perform different functions.

Most importantly, do not substitute caulk for flashing. A sealed lower edge can trap water behind cedar when the drainage detail is incomplete.

How much clearance should cedar siding have above roofing, decks, grade and flashing?

General Western Red Cedar guidance gives these minimums:

• 1/4 inch above a flashing ledge
• 2 inches above roofs
• 2 inches above decks
• 6 inches above grade for water-table or skirt-board trim

The exact siding product, adjoining assembly, snow or splash exposure, and applicable requirements may call for more. Some shingle base details prescribe another clearance above bottom flashing, so use the applicable drawing rather than combining unrelated measurements.

Can I use a nail gun to apply cedar shingles?

Yes, when the shingle manufacturer permits pneumatic fastening and the specified fastener is used. Adjust tool pressure so the head finishes flush rather than buried in the cedar. Because shingle thickness varies, inspect the installation continuously instead of relying on one compressor setting for the entire wall.

Nails or staples must not remain visible in side joints or keyways. CSSB permits nail-gun use but treats overdriven heads and visible joint fasteners as installation defects.

Do cedar siding fasteners need to hit studs?

For the cited Western Red Cedar bevel method, face nails go into studs or other specified solid support and provide at least 1-1/4 inches of solid-wood penetration. Other products may approve blocking, furring, structural sheathing, or a tested attachment system.

There is no universal rule that ordinary sheathing alone is sufficient. Verify:

• Siding profile and orientation
• Sheathing material and thickness
• Framing, blocking, and furring locations
• Exterior-insulation thickness
• Fastener type, length, and spacing
• Required penetration
• Wind exposure
• Product approval
• Applicable local requirements

The final verification is compact but decisive: confirm the exact profile and grade, approved wall and drainage assembly, flashing continuity, required clearances, profile-specific overlap or keyway, compatible fastener and penetration schedule, supported joints, protected cuts, and open drainage paths.

Applying cedar siding successfully is less about finding one universal nailing pattern than coordinating water shedding, drying, wood movement, and attachment for the selected product and the wall behind it.