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SHEDS & OUTBUILDINGS

Shed Roof Leaking

A leaking shed roof is commonly caused by damaged felt, failed overlaps, loose fixings, cracked sealant or water tracking from a joint.

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Check structural stability and electrical safety first

Do not climb onto weak roofs or work around wet electrics. Stop if floors, walls or roof timbers are soft, sagging or unstable.

MOST LIKELY CAUSES

Start with water paths, timber condition and the base

Damaged roof felt Tears, splits or worn areas let water through.
Failed overlaps or joints Water enters where sheets or felt sections meet.
Loose fixings Nails or screws lift and open a path for rain.
Poor edge or flashing detail Water gets behind trims, flashings or wall junctions.
◫ Symptom variations Match the leak, movement or moisture pattern. ⌄
  • Leak appears only in heavy rain
  • Water stain near roof edge
  • Drip starts away from visible damage
  • Felt is wrinkled or split
  • Timber beneath roof feels soft
✓ Quick checks Safe checks before dismantling the shed. ⌄
  1. Inspect the roof only from a safe position.
  2. Check felt seams, edges and fixings.
  3. Trace the highest damp point inside.
  4. Look for ponding water.
  5. Inspect wall-to-roof junctions and trims.
Important: Fix the water source or structural movement before replacing damaged timber or finishes.
1 Step 1 — Find the real entry point Make the smallest safe correction and retest. ⌄

Water can travel along boards before dripping.

2 Step 2 — Make the area weather-tight Make the smallest safe correction and retest. ⌄

Patch small isolated defects with compatible materials.

3 Step 3 — Replace failed covering where necessary Make the smallest safe correction and retest. ⌄

Renew badly aged felt or damaged sheets rather than adding repeated patches.

⌁ Why the problem happens How moisture, movement and weather affect outbuildings. ⌄

Roof leaks often travel beneath the covering before becoming visible indoors, so the drip point may not match the entry point.

⌘ Advanced checks Further diagnosis for persistent shed faults. ⌄
  1. Check roof fall.
  2. Inspect deck condition.
  3. Assess eaves and drip edges.
  4. Check flashing upstands.
  5. Look for condensation mistaken for leakage.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Torch
  • Ladder used safely
  • Roofing brush
  • Utility knife
  • Tape measure
▣ Parts or improvements that may help Common materials linked to this problem. ⌄
  • Roof felt
  • Felt adhesive
  • Roofing nails
  • Flashing tape
  • Timber roof deck
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The roof structure is soft or sagging.
  • The shed is large or high.
  • Asbestos-containing sheets may be present.
  • Electrical equipment has become wet.
  • The leak involves major roof replacement.
? Frequently asked questions Common shed and outbuilding questions. ⌄

Why does the leak appear away from the damage?

Water can travel under felt or along roof boards.

Can I patch wet felt?

Repairs bond best to a clean, dry surface.

Should old felt be covered again?

Only if the deck and existing covering are suitable; badly failed felt is better replaced.