How to Fix a Roof Leak: Temporary Patches and Permanent Repairs
Stop the water first, then fix the cause. A tarp, a patch of roofing cement or a replacement shingle will hold a leak for a few weeks; flashing, valleys and anything structural need a lasting repair, and several of them are best left to a roofer.
Before you go up
Do not climb onto a wet, frosty or windy roof, and do not go up while it is still raining. Use a ladder that reaches at least 3 feet above the eave, set on firm, level ground at roughly one foot out for every four up. On a steep or high roof, or if you are not comfortable with heights, stay off it. A leak is not worth a fall, and the work below can wait for a roofer.
Stopping the water now
Indoors, contain the water and protect the room first. What to do when you discover a roof leak covers buckets, ceiling relief and switching off power to fixtures below. Then, from outside:
- Tarp it. Cover the damaged area with a tarp that extends several feet beyond it in every direction, with the upper edge tucked under the shingles or run over the ridge. Fasten it to the roof or weigh it down so wind cannot lift it, and drain any water pooled on the tarp.
- Patch a small hole or crack. Clean and dry the surface, then press roofing cement over the damage. This is a stopgap only.
- Replace a missing shingle. Slide a new one into the gap, nail it, and dab cement under the tabs. It is the one temporary fix that is close to a real repair on a low, safe roof.
The first 48 hours after a storm explains how to cover a roof after storm damage. Plan the permanent repair for the first dry week.
Permanent repairs by location
| Where the leak is | Usual cause | Permanent repair | DIY or hire | Typical cost |
|---|---|---|---|---|
| Missing or cracked shingles | Wind, age | Replace the shingles and reseal the tabs | DIY on a low, safe roof | $150 to $500 |
| Vent pipe boot | Cracked rubber collar | Replace the boot | DIY, moderate; see vent pipe boot leaks | $150 to $400 |
| Flashing at a wall or chimney | Failed or missing flashing, dried sealant | Re-flash; caulk alone is only a stopgap | Hire for a chimney; wall flashing is moderate | $200 to $500 simple; $500 to $2,000 for a chimney |
| Skylight | Flashing or seal failure | Reseal or reflash, or replace the unit | Hire | $300 to $800 to reseal |
| Valley | Worn metal or shingles | Rebuild the valley | Hire | $500 to $2,000 |
| Rotten decking | A long-running leak | Cut out and replace the boards | Hire | $70 to $150 per sheet installed |
The costs are the ranges in how much it costs to repair a roof. If you are not sure which row applies, how to find a roof leak traces the leak to its entry point.
Why a patch is not a repair
Cement and caulk dry out and crack within a season or two, and water then finds a new path beside the patch. Sealant is not flashing, and a leak around a penetration that has been sealed twice is a leak that needs the flashing replaced. If the same spot leaks again after a repair, the repair treated the symptom.
When a leak means more than a repair
Several leaks, a soft or sagging deck, or an old roof with leaks in different places point to a roof near the end of its life, and repeated patching then costs more than it saves. When repairing a roof stops being worth it sets out the test, and how much a new roof costs shows what replacement involves.
More roof leak guides
- Why a roof leaks: common causes
- How to find a roof leak
- Roof vent pipe boot leaks
- Signs of roof damage you should never ignore
- Roof leak or attic condensation
- What roof flashing is and why it leaks
- What to look for in your attic
- What causes ice dams
- Ponding water on a flat roof
The Roof Leak Finder points to the likeliest cause from where and when the water appears.
Conclusion
To fix a roof leak, work in two stages: stop the water today with a tarp, a patch or a replaced shingle, then repair the cause in dry weather. Do the simple repairs yourself only where you can reach them safely, and leave flashing, valleys and structural damage to a roofer.
