Seal a leaking gutter seam
Clean and reseal a sound gutter joint without blocking its drainage.
Lawn & garden · 1–2 hr + cure · Medium
Before you start
Do not work from a roof or overreach a ladder. Use a stable rated access setup on firm ground, away from power lines; hire help if safe access is unavailable. Wear cut-resistant gloves and eye protection; follow cleaner and sealant ventilation warnings.
Tools and materials
- Compatible gutter sealant and approved cleaner
- Caulk gun, plastic scraper, nonabrasive pad, cloths, debris scoop, gloves and safe rated access equipment
Check the problem
Confirm where water escapes
Observe during rain from the ground or a controlled low-flow test. Overflow from debris or water behind the gutter is different from a leaking lap seam.
Check that the joint is sound
Inspect for loose fasteners, corrosion and sagging. Sealant cannot restore missing metal or secure a detached gutter.
Steps
Choose safe access and weather
Arrange stable access and a helper as needed. Check application temperature, rain forecast and cure requirements on the chosen sealant.
Clear debris
Scoop leaves and sediment around the joint and make sure the outlet is clear. Do not push debris into the downspout.
Remove failed material
Remove failed old sealant completely from the intended bonding surfaces with a plastic scraper and approved cleaner. Do not damage the metal or finish; leave the lap and its sound fasteners assembled.
Clean and prepare
Scrub with the approved pad and cleaner, then let the joint reach the dryness required by the sealant. Do not assume all gutter products adhere to wet surfaces.
Seal the interior joint
Apply a continuous bead along the interior seam and around leaking fasteners as directed. Tool it into full contact without building a dam across the gutter.
Cure and test
Wait the specified water-exposure time. Run a gentle flow from upstream and watch below the joint. Confirm no drips, no backed-up water and free discharge.
Wait the specified water-exposure time. Run a gentle flow from upstream and watch below the joint. Confirm no drips, no backed-up water and free discharge.
Tips
Read the metal and coating limits
Not every exterior caulk is suitable for gutters.
Keep water moving
A large ridge of sealant can collect debris and standing water.
Do not seal over corrosion
Holes and loose joints need repair or replacement, not a thicker bead.