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Fix a roof valley that leaks

We'll confirm the leak is in the valley, rule out debris and ice dams, then repair the valley metal or sealant—or tell you when to call a roofer.

Troubleshooting · Home maintenance
1–3 hours
What you'll need
  • Ladder (sturdy, properly positioned)
  • Roof cement or valley sealant
  • Putty knife or trowel
  • Leaf blower or hand tools (for clearing debris)
Step 1 of 8

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Steps

Goal: Confirm the leak is in the valley, rule out debris and ice dams, then repair—or call a roofer when needed.

  • Confirm the leak correlates with the valley and with rain. Trace the stain or drip upward.
  • Good: Leak is in the valley and appears with rain. Proceed to Check debris first.
  • Bad: Leak does not correlate—see fix-roof-leaks for general tracing.

Check debris first

Goal: Rule out debris and ice dams as the cause.

  • From a ladder, look for leaves, pine needles, or ice dams blocking the valley. Do not walk in the valley—it can damage the metal.
  • Clear debris with a leaf blower or by hand. For ice dams, improve attic ventilation; remove ice carefully.
  • Good: Valley is clear. Proceed to Inspect valley.
  • Bad: Debris was blocking—clear and test after rain. If the leak continues, inspect the valley metal.

Inspect valley

Goal: Assess the valley metal or sealant condition.

  • Look at the valley from a ladder. Metal valleys: check for rust, corrosion, gaps at seams. Sealed valleys: check for cracked or missing sealant.
  • Good: Small gaps or rust spots—seal with roof cement. Bad: Severely corroded or rusted through—call a roofer.

Seal path

Goal: Seal small gaps and rust spots in the valley.

  • Clean the area. Apply roof cement or valley sealant to cover gaps and overlap onto sound metal.
  • Work from the side—do not walk in the valley. The valley channels a lot of water; small repairs can help.
  • Good: Gaps are sealed. Test after rain.
  • Bad: Damage is severe—call a roofer for valley metal replacement.

When to get help

Call a roofer if:

  • The valley metal is severely corroded or rusted through.
  • The valley is complex (woven or closed-cut).
  • You cannot safely access the roof.
  • You have cleared debris and sealed and the leak continues.

Valley work is hazardous. Do not risk a fall.

Verification

  • Valley is clear of debris.
  • Gaps and rust spots are sealed with roof cement.
  • No new water entry after the next rain.
  • Water flows down the valley without backing up.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm leak location Verify the leak correlates with the valley and with rain.
  2. Check debris and ice dams Clear debris; assess ice dams and ventilation.
  3. Inspect valley Look for rust, gaps, or damaged sealant.
  4. Seal or call roofer Seal small gaps if safe; otherwise call a roofer.
  5. Call a roofer Severe valley damage, complex valley, or unsafe access—call a roofer.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Where the leak appears (ceiling, attic)
  • Whether debris or ice dams are present
  • Valley metal or sealant condition
  • Roof pitch and access safety
  • Steps already tried

Does the leak correlate with the valley and rain?

Trace the leak upward. Valleys are where two slopes meet. Confirm the leak appears during or after rain.

Note where water appears. Trace it upward to the roof. Valley and rain: proceed to check debris. Not valley or not rain: may be different source—see fix-roof-leaks.

Yes No

You can change your answer later.

May not be valley leak

If the leak does not correlate with the valley or rain, the source may be elsewhere—check gutters, flashing, or other roof areas. See fix-roof-leaks for general leak tracing.

Done

Is debris or ice blocking the valley?

Blocked valleys cause water to back up under shingles.

From a ladder, look for leaves, pine needles, or ice dams in the valley. Blocked: clear debris; remove ice carefully (do not chip). Clear: proceed to inspect valley metal.

Yes No

You can change your answer later.

Clear debris and test

Clear debris from the valley. Use a leaf blower or hand tools from a ladder—do not walk in the valley. After the next rain, check if the leak continues. Stopped: debris was the cause. Continues: inspect valley metal.

Done

Is the valley metal or sealant damaged?

Rust, gaps, or failed sealant let water in.

Inspect the valley metal from a ladder. Look for rust, corrosion, gaps at seams, or cracked sealant. Small gaps or rust: seal with roof cement. Severely corroded or rusted through: call a roofer.

Yes No (leak continues)

You can change your answer later.

Can you safely access the roof?

Valleys are often steep. Do not walk in the valley.

Check roof pitch and access. Safe access: seal small gaps with roof cement—work from the side, not in the valley. Steep or high: call a roofer.

Yes No

You can change your answer later.

Seal and test

Clean the area and apply roof cement or valley sealant to cover gaps and rust spots. Overlap onto sound metal. Test after the next rain. If the leak continues, the damage may be beyond DIY—call a roofer.

Done

Call a roofer

Call a roofer if: the valley metal is severely corroded, the valley is complex, you cannot safely access the roof, or the leak continues after clearing and sealing. Valley work is hazardous—do not risk a fall.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why does a roof valley leak?
Valleys channel a lot of water. Common causes: debris or ice dams blocking flow (water backs up under shingles), rust or corrosion in metal valleys, failed sealant, or damage from foot traffic. Valleys are high-wear areas.
Can I fix a valley leak myself?
Yes, for minor repairs—clearing debris, sealing small gaps with roof cement. Replacing valley metal or repairing complex valleys requires roof access and skill. Do not go on a steep or wet roof—call a roofer.
When should I call a roofer for a valley leak?
Call a roofer if the valley metal is severely corroded or rusted through, the valley is complex (woven, closed-cut), you cannot safely access the roof, or you have cleared debris and sealed and the leak continues.

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