How To Seal Leaky Metal Gutters With Caulk

Posted on: 15 August 2016


If your residential gutters leak, but they show no signs of major damage, reapply the caulking. Caulking is necessary to seal the seams between gutter panels to form a tight water seal. Sometimes, it is improperly applied during the installation of the gutters, or it gets worn from age. You should be able to caulk the seams yourself. Here are tips to caulk a rain gutter.

Prepare to Work

For this project, you need:

  • ladder
  • work gloves
  • damp cloth
  • masking tape
  • carpenter's level
  • needlenose pliers
  • scouring pad or old toothbrush
  • wire brush
  • chisel
  • utility knife
  • putty knife
  • sand paper
  • caulk remover
  • trisodium phosphate or bleach
  • silicone caulk and caulk gun

Set a ladder on flat ground, and get someone to hold it for you, if needed. Locate the uphill gutter by placing a carpenter's level on the roof edge at the gutter. The higher side is the uphill piece, and the lower side is called the downhill piece.

Check for holes and rust. Also inspect the joints around downspouts, which are prone to leaks because of the water force.

Remove the Old Caulk

Moisten the old caulk with the caulk remover to soften it. Use the utility knife to cut down the middle of the caulk, and pull it off with the needlenose pliers. Chisel caulk that remains.

Use a wire brush to scrub rust around the joints or holes, if needed, and wipe with a damp cloth. Make a mixture of trisodium phosphate and water, and scrub the gutter with the scouring pad or old toothbrush. You may also use a mixture of one-third cup of bleach and water.

Let the area dry before applying new caulk. If it gets wet before you apply new caulk, dry it with a towel.

Apply the New Caulk

Silicone caulk works best in extreme temperatures, and it lasts longer than latex caulk. If possible, buy a caulk especially made for gutters.

Lightly sand the area to roughen up the surface, and remove burrs caused by the wire brush. Use the damp cloth to clean particles. You don't have to make jagged edges, but sand enough to make it slightly coarse. A rough edge helps the caulk adhere better.

Cut the tip of the caulking tube with the knife at a forty-five degree angle, so the tube fits into the gun  easier. Secure the tube into the caulk gun at both ends. Apply a bead of caulk into the lip of the downhill piece, smoothing gaps with the putty knife.

Press the uphill piece into the seam of the downhill piece. Place masking tape over the seams while they dry. Fill holes or cracks with caulk as you move along.

Gutters must be checked and caulked again periodically. If you don't trust your skill, or the gutter is seriously damaged, contact a gutter service like Gutter Magician NKY.