Meta description: Learn how to felt a shed roof with the right materials, preparation, installation steps, and maintenance tips for a weather-resistant finish.
Felt can provide a practical, affordable covering for many small shed roofs, but a long-lasting result depends on choosing the right product and installing it correctly. In the United States, “roofing felt” may mean either an underlayment installed beneath shingles or a finished, mineral-surfaced roll roofing product left exposed to the weather. Those materials are not interchangeable. This guide explains how to felt a shed roof using exposed roll roofing, what to check before starting, and when a different roofing system may be a better choice.
Choose the Right Roofing Felt
Before buying materials, confirm whether the product is designed to serve as the roof’s finished, exposed surface. Basic asphalt-saturated underlayment—often called roofing felt or tar paper—is generally intended to go beneath another roof covering. It usually does not have the durable, UV-resistant surface needed for long-term exposure. For a felt-only shed roof, look for a product labeled for exposed application, such as mineral-surfaced asphalt roll roofing, and follow its current installation instructions.
Roll roofing products vary in composition, width, weight, fastening method, and minimum roof slope. Some use exposed nails; others require lap cement or a specific combination of fasteners and adhesive. Product requirements can change, so the manufacturer’s instructions should take priority over general guidance. If the label does not clearly state that the product can be used as a finished roof covering, do not assume it can.
Roof pitch matters, too. A shallow-pitched roof drains more slowly and is more vulnerable to water backing up under seams. Check the product’s minimum slope and any special low-slope instructions before purchasing. If the shed roof falls below the product’s allowed pitch, choose a covering rated for that condition or consult a roofing professional.
Check the Roof and Local Requirements
Inspect the shed framing and roof deck before covering anything. The deck should be structurally sound, firmly fastened, dry, and reasonably flat. Replace rotted, delaminated, or badly warped sheathing. Hammer down protruding fasteners and remove old roofing, loose debris, and anything that could puncture the new material. Roofing felt will not correct weak framing or an uneven, damaged deck.
Look for a clear drainage path. The roof should direct water toward the eaves rather than against a wall, into a valley, or toward an opening. Existing fascia, drip edge, gutters, and wall flashing may affect the order of installation. A shed attached to a house or garage needs particular attention at the wall connection: the roof covering alone is not a substitute for properly installed flashing.
Local building codes and permit rules vary by location, shed size, and whether the structure is attached to a home. Some jurisdictions also regulate wind resistance and roofing materials. Check with the local building department when requirements are unclear. Manufacturer instructions, local code, and the project’s site conditions should guide the final installation.
Materials and Tools
Exact quantities depend on roof dimensions, roll size, and the required overlap. Measure the roof, then account for eaves, rakes, ridges, and waste. For a simple rectangular roof, calculate its surface area by multiplying the roof’s length by its slope length—not by the building’s horizontal depth. If the roof has several sections, calculate each section separately.
- Exposed-use roll roofing: Select a product approved for the roof’s pitch and application.
- Roofing nails or specified fasteners: Use the type and length recommended by the manufacturer.
- Roofing cement or lap adhesive: Use only where and in the amount specified for that product.
- Drip edge and flashing: Use compatible components where required for the roof design.
- Measuring tape and chalk line: For layout and straight courses.
- Utility knife and straightedge: For controlled cuts.
- Hammer or compatible nailer: For fastening according to the product instructions.
Do not substitute general-purpose caulk for roofing cement or lap adhesive unless the roofing manufacturer specifically approves it. Using too much cement, placing nails outside the prescribed fastening zone, or selecting incompatible materials can lead to leaks or premature failure.
Plan for Safety and Weather
Choose a dry day with mild temperatures and little wind. Wet roofing, icy surfaces, and strong gusts increase the risk of slipping or losing control of a roll. Very cold conditions can make asphalt products stiff and prone to cracking; high heat can make them soft and difficult to handle. Follow the product’s temperature guidance and store rolls as directed before installation.
A shed roof may be low, but a fall can still cause serious injury. Set ladders on firm, level ground, secure them where possible, and keep the climber’s body between the side rails. Wear slip-resistant footwear, gloves, and eye protection. Avoid working alone if practical, and keep tools and materials from sliding off the roof. The U.S. Occupational Safety and Health Administration provides guidance on ladder safety; its recommendations are useful even for small home projects.
If the roof is steep, high, structurally questionable, or difficult to access safely, stop and hire a qualified roofing contractor. Do not work on a roof during rain, frost, or high winds.
How to Felt a Shed Roof
1. Prepare the deck and edges
Make sure the roof deck is clean, dry, and securely fastened. Confirm that the eaves and rake edges are straight enough to guide the roofing. Install drip edge or other edge metal if the roof design and product instructions call for it. Edge-metal placement can differ by system: some instructions put it beneath the underlayment at the eaves and over it at the rakes, while a finished roll-roofing system may specify another arrangement. Follow the instructions for the complete assembly rather than applying a universal rule.
2. Measure, position, and cut the first course
Unroll a manageable length of roofing and let it relax if the manufacturer recommends doing so. Begin at the lower edge of the roof so the upper courses overlap the courses below and shed water toward the eaves. Align the first course with the edge, allowing only the overhang specified for the product and edge detail. Use a chalk line to keep the course straight, then cut it with a utility knife on a protected surface.
3. Fasten the lower course
Secure the sheet using the product’s prescribed nail pattern, fastener type, and edge distances. Keep nails straight and seated snugly; overdriven or angled nails can damage the roofing, while underdriven nails may leave raised heads. Some exposed roll roofing systems also require roofing cement at the eave or along particular edges. Apply it only where specified, and avoid leaving excess material that can interfere with the next course.
4. Add the next course with the correct overlap
Place the next strip above the first, overlapping it by the amount stated in the product instructions. The required overlap varies by product and roof pitch, so there is no single measurement that suits every shed. Use a chalk line to maintain a straight edge. Fasten the course according to its instructions, paying close attention to whether the fasteners will be covered by the next layer or exposed to weather.
Continue upward in parallel courses until the roof is covered. Arrange overlaps so water flows over each seam rather than into it. Keep sheets flat and free of wrinkles, folds, and trapped debris. If a roll is short, use the manufacturer’s method for end laps and stagger end joints where instructed; avoid placing several seams in one line unless the product details permit it.
5. Finish the ridge, rake edges, and penetrations
At the upper edge, finish the ridge or roof-wall connection with the detail required by the roofing system. A ridge cap may need a separate strip or formed piece. For a shed roof that meets a vertical wall, use appropriate step or continuous flashing as the design requires; roofing cement alone is not a reliable replacement for proper flashing.
At rakes and other exposed edges, trim the material neatly and secure it as directed. Around vents or other roof penetrations, use compatible flashing and seal the details according to the product instructions. Unusual corners, valleys, and wall intersections are frequent leak points. If the shed has complicated roof geometry, the product’s installation guide or a professional can help determine the correct detail.
Common Installation Mistakes
- Using underlayment as the finished roof: A product designed to be covered may degrade when left exposed. Verify the label before installation.
- Ignoring minimum slope: A material suitable for a steeper roof may not perform on a shallow shed roof.
- Reversing or reducing overlaps: Incorrect laps can direct water beneath the roofing instead of over it.
- Fastening without following the pattern: Incorrect nail placement can leave exposed leak paths or allow wind to lift the roofing.
- Covering damaged sheathing: New roofing cannot repair rot, weak framing, or an unstable deck.
- Skipping flashing: Wall joints and penetrations need designed water-shedding details, not just a bead of sealant.
- Installing in unsuitable weather: Wind, moisture, and temperatures outside the product’s range make installation less safe and less reliable.
Inspection and Maintenance
After installation, inspect the roof from a safe position. Check that courses are straight, edges are secure, and no fasteners are loose or standing proud. Look for lifted corners, open seams, cuts, or areas where water could collect. Do not walk on the roofing unless the product instructions permit it; foot traffic can damage some surfaces.
Check the shed roof periodically, especially after strong wind, heavy rain, or snow. Keep leaves and branches from blocking drainage, and trim nearby vegetation that rubs against the roof. Address small defects promptly using repair materials compatible with the roofing product. If leaks recur, the cause may be a failed flashing detail, inadequate slope, damaged deck, or unsuitable roofing material rather than a simple surface defect.
When Felt Is Not the Best Choice
Exposed roll roofing can be suitable for some small sheds, but it is not the right solution for every building. Consider the roof’s pitch, climate, expected service life, appearance, and local rules. In areas with severe wind, frequent hail, heavy snow, or prolonged standing water, another roofing system may better match the conditions. Shingles, metal panels, or a membrane roof each have their own minimum-slope, underlayment, fastening, and flashing requirements.
For a durable shed roof, the key decisions are straightforward: use a product specifically rated as an exposed roof covering, confirm that it suits the roof slope, prepare a sound deck, and follow the manufacturer’s complete installation details. That approach gives the roofing a better chance of shedding water reliably and makes future maintenance easier.
Helpful references: Review the roofing manufacturer’s product label and installation instructions, local building department requirements, and OSHA ladder safety guidance before work begins.