How to Replace Shed Roof Plywood Safely

Replacing shed roof plywood is a common maintenance task that extends a shed’s life and prevents water damage. This guide covers planning, materials, step-by-step removal and installation, ventilation, flashing, and cost considerations so readers can complete a durable plywood replacement with confidence.

Step	Key Action	Estimated Time
Inspection & Prep	Assess damage, gather tools	1–2 hours
Remove Old Roofing	Strip shingles/fasteners	2–4 hours
Replace Plywood	Cut, fit, fasten new sheathing	3–6 hours
Install Underlayment & Flashing	Weatherproof roof	1–3 hours
Install New Roofing	Shingles/metal/etc.	2–6 hours

When To Replace Shed Roof Plywood

Signs that indicate a plywood replacement include sagging roof sections, visible rot, persistent leaks, or soft spots underfoot. If multiple rafters or large plywood areas are compromised, full sheathing replacement is recommended rather than localized patches.

Materials And Tools Needed

Common materials include 1/2″ or 5/8″ exterior-grade plywood or CDX sheathing, roofing felt or synthetic underlayment, drip edge, starter strip, shingles or metal roofing, roofing nails, and sealant. Essential tools are circular saw, pry bar, roofing nailer or hammer, chalk line, tape measure, utility knife, safety gear, and a reciprocating saw if needed. Select plywood rated for roof sheathing (exterior-grade, APA stamped) to ensure durability.

Preparing The Shed And Safety Precautions

Before starting, remove contents from near the shed, set up ladders and scaffolding, and ensure stable footing. Use fall protection when working on steep pitches above 6/12. Wear gloves, eye protection, and a dust mask to prevent injury and inhalation.

Step-By-Step Removal Of Old Roof Materials

1. Remove Shingles Or Metal Roofing

Start by removing shingles or metal panels beginning at the ridge and working down. For shingles, use a roofing shovel or pry bar to lift and remove nails. For metal panels, unfasten screws and remove panels carefully. Keep nails and debris contained to protect the site and workers.

2. Strip Underlayment And Flashing

Once top layers are off, peel back roofing felt or synthetic underlayment and remove drip edge and flashing. Inspect for hidden rot where flashing met the plywood. Note locations of flashing and vents to reinstall or upgrade later.

3. Remove Damaged Plywood

Score around damaged plywood sheets with a circular saw set to the plywood thickness to avoid cutting rafters. Pry up the sheet and remove nails with a hammer or reciprocating saw. Temporarily shore up any weakened areas if necessary. Cut and remove plywood in full sheets when possible to simplify replacement.

Choosing The Right Plywood Thickness And Type

Most shed roofs use 1/2″ or 5/8″ plywood; 5/8″ provides more rigidity for wider rafter spacing. Use exterior-rated or CDX plywood with an APA stamp. For heavy snow loads or wider spans, consider 3/4″ or OSB rated for roof sheathing. Match sheet thickness to rafter spacing and local building code requirements.

Measuring, Cutting, And Fitting New Sheathing

Measure rafter spacing and roof dimensions to determine plywood layout. Stagger end joints over rafters and leave a 1/8″ gap between sheets to allow for expansion. Use a chalk line for straight cuts and a circular saw for accuracy. Plan joints so seams fall on rafters for secure fastening.

Nailing Patterns And Fastening Best Practices

Fasten plywood with 8d ring-shank nails or 1-1/4″ to 1-5/8″ screws every 6″ along edges and 12″ in the field for typical rafter spacing. Use a pneumatic nailer for speed and consistency. For metal roofing underlayment or high-wind areas, follow manufacturer fastening patterns. Proper fastener length and spacing prevent squeaks and uplift.

Installing Underlayment, Drip Edge, And Flashing

After sheathing, install drip edge along eaves, then roll out roofing felt or synthetic underlayment from eave to ridge, overlapping according to manufacturer instructions. Install starter strips at eaves, cap flashing at ridges, and step flashing where roof meets walls. Ensure continuous water-shedding layers to protect new plywood.

Ventilation And Insulation Considerations

Proper attic ventilation prevents moisture buildup that can rot plywood. If the shed has an attic space, add ridge vents and soffit vents or gable vents to provide balanced airflow. For insulated sheds, add a vapor barrier and ensure ventilation paths remain clear. Good ventilation extends the life of the roof sheathing and roofing materials.

Common Mistakes To Avoid

• Skipping underlayment repairs: Installing new roofing over compromised underlayment invites leaks.
• Incorrect fastener lengths: Nails that are too short or long can fail or split rafters.
• Poor joint placement: End joints not supported by rafters lead to sagging.
• Insufficient ventilation: Traps moisture and accelerates plywood rot.

Disposal, Recycling, And Environmental Considerations

Old plywood and roofing materials should be disposed of at a licensed landfill or recycling center. Separate metal roofing for recycling and bundle shingles per local disposal rules. Consider using recycled-content roofing or longer-life metal panels to reduce future waste.

Estimated Costs And Timeframe

Costs vary by material and size; typical replacement for a 10×12 shed ranges from $400 to $1,200 for plywood and underlayment, plus $200–$1,500 for roofing materials depending on type. Labor for a DIYer might take 1–3 days, while contractors may finish in a day. Obtain multiple quotes for professional work and factor permits if required.

When To Hire A Professional

If the shed roof has complex flashing, structural damage to rafters, steep pitch, or local code issues, hiring a licensed contractor is advisable. Professionals provide structural repair, warranty, and ensure compliance with local codes. For safety or structural uncertainty, choose a pro to avoid costly mistakes.

Upgrades And Long-Term Maintenance Tips

Consider upgrading to plywood treated for increased moisture resistance or replacing sheathing with OSB rated for roof use. Maintain gutters, trim overhanging branches, and inspect the roof annually for damage. Timely repairs and annual inspections prevent minor issues from becoming major problems.

Checklist For A Successful Plywood Replacement

• Inspect and document roof condition
• Gather materials, tools, and safety gear
• Remove old roofing and plywood carefully
• Install new plywood with proper gaps and fastening
• Apply underlayment, flashing, and new roofing
• Check ventilation, clean site, and dispose responsibly

Following these steps ensures a reliable shed roof plywood replacement that protects the structure and contents. For local code specifics or structural concerns, consult a building professional before starting work.