Felt a garden shed roof by working from the eaves upward in overlapping strips, securing each layer with galvanised clout nails and bitumen adhesive, and finishing with a ridge cap and replaced fascia boards.
A leaky shed roof ruins what’s stored inside and rots the structure itself. Correctly installing new felt stops that, and the procedure is straightforward for a weekend job. Whether you have an apex roof with two slopes or a pent roof with one, the method is the same: strip the old material, prepare the deck, and lay new felt from the bottom edge upward. Here is the exact sequence that gives you a weathertight shed for years.
Felt Types and What Lasts
Your choice of felt determines how often you repeat this job. Three types are common for garden sheds, and each has a different lifespan.
- Mineral felt — the budget option, lasting 5 to 10 years.
- Polyester felt — much tougher, lasting 15 to 20 years or more.
- Torch-on felt — the most durable, also 15 to 20 years, but requires a propane torch for installation and is less common on DIY sheds.
If you plan to keep the shed for a while, polyester felt is worth the extra cost — the labor is identical, so you might as well make it count.
Prepping the Roof: Strip, Clean, Fix
Start by removing the timber fascia boards with a pry bar and set them aside. Pull out all nails and staples holding the old felt using a claw hammer, then cut the felt away with a sharp utility knife. Clear every scrap of felt, debris, and stray fastener from the roof. A clean deck is the foundation of a leak-free install.
Any damp, delaminated, or rotted OSB or plywood boards must be replaced. Re-nail or screw down any boards that have lifted. Drive any proud nail heads flush or just below the surface with a nail punch. The deck must be completely dry before you lay any felt — installing on a damp surface traps moisture and causes early failure.
If your shed roof needs more than just felt, our tested best garden shed roof guide covers complete replacement options and materials.
Measuring, Cutting, and Laying the Felt
Measure from the eaves to the ridge (the peak) for each slope. Add 10 cm total for the overhang at the eaves and sides. For gable ends where the felt tucks under the fascia, add another 15 cm. Cut each strip on a clean, flat surface with a sharp utility knife. After cutting, unroll the strips on a flat surface for at least 30 minutes before installation — this relaxes the material and makes it easier to lay flat.
| Dimension | Required Measurement |
|---|---|
| Eaves overhang | 50–75 mm (5–7.5 cm) |
| Side (gable) overhang | 50–75 mm (5–7.5 cm) |
| Horizontal overlap between strips | Minimum 75 mm (7.5 cm) |
| Ridge cap overlap onto each slope | 75 mm (7.5 cm) |
| Top edge (ridge) nail spacing | 100 mm intervals; 50 mm along overlaps |
| Bottom edge (eaves) nail spacing | 300 mm intervals |
| Side/rake nail spacing | 75 mm intervals when folding overhangs |
| Nail type | 13 mm galvanised clout nails |
Laying the First Strip (Eaves)
Position the first strip at the lowest edge of the roof, allowing 50–75 mm of overhang past the eaves. Unroll it straight and mark a light pencil line if needed to keep alignment. Nail the top edge first at 100 mm intervals, starting from the center and working outward to avoid wrinkling. Then nail the bottom edge (the eaves) at 300 mm intervals. Pull the felt tight after securing the inner side to ensure it lies flat.
Working Upward
Apply bitumen roofing adhesive evenly along the top edge of the first strip using a brush. Position the second strip so it overlaps the first by a minimum of 75 mm. Nail through both layers along the overlap line at 50 mm intervals. Continue this process — adhesive, overlap, nail — working upward until you reach the ridge.
Ridge Cap and Gable Ends
Cut a ridge cap strip wide enough to overlap both slopes by 75 mm on each side. Apply adhesive to its underside, press it down firmly, and nail both sides at 100 mm intervals. At the gable ends, fold the excess felt outward to form a flap, fold it back along the eaves, and nail at 75 mm intervals. For the verge (the sloped edge of a gable), cut a small slit at the center point so the felt sits flat, then fold the remaining section over and secure it. Dress all overhangs over the roof edges to create a drip that channels water away. Reattach the fascia boards over the felt using wood nails — this locks the edges in place and gives a finished look. Cover all exposed nail heads with roofing adhesive to prevent water ingress.
Three Mistakes That Cause Leaks
- Too little overlap. Any overlap under 75 mm between strips will let water seep through. Measure every one.
- Skipping the adhesive. Nails alone won’t stop wind-driven rain from getting under the overlap. Brush bitumen adhesive on every seam.
- Starting at the top. If you lay the top strip first, water runs behind the lower strips. Always start at the eaves and work up.
FAQs
Can I use tar paper instead of shed felt?
It works on flat or low-slope roofs but is not a direct swap for the heavier mineral or polyester felt used on garden sheds. Stick with shed felt for the best results on a steep pitched roof.
Do I need to put anything under the shed felt?
If you use one, follow the underlay manufacturer’s instructions for overlap and fixing spacing.
How long does a felted shed roof last?
A mineral felt roof lasts 5–10 years, while a polyester felt roof lasts 15–20 years or more. The lifespan depends on local weather, deck condition, and installation quality — good overlap, proper nailing, and sealed seams make the biggest difference.
References & Sources
- DIY.com. “How to felt a shed roof.” Step-by-step guide covering preparation, installation, and finishing.
- Ideal Home. “How to felt a shed roof.” Covers materials, overhang specifications, and common mistakes.
- Roof Giant. “RoofPro Shed Felt Installation Guide.” Manufacturer installation instructions with nail spacing and overlap details.