Repair A Hairline Crack In A Foundation Wall And Apply A Waterproofing Agent

Posted on: 3 November 2016

If a hairline crack surrounding one your basement's windows causes water to drip through the concrete surface whenever it is raining heavily, resolve the problem by completing the steps below. Afterwards, clean and seal the interior walls to provide the concrete with a protective barrier that will prevent moisture from entering your home.


  • handheld scrub brush
  • shop vacuum cleaner (with suction hose)
  • tube of concrete repair patch
  • caulk gun
  • small trowel
  • concrete cleaning agent
  • sponges
  • bucket of water
  • several towels
  • vinyl drop cloths
  • waterproofing agent
  • paint tray
  • thick-napped paint roller and frame
  • extension handle

Repair The Crack And Clean The Concrete

Lightly rub the cracked surface with a scrub brush to remove any loose fragments of concrete. If small pieces of concrete are stuck inside of the crack, remove them by suctioning them with a shop vacuum cleaner's hose. Fill the crack with a line of concrete repair patch. Smooth out the patch with a trowel until the repaired area is flush with the other parts of the wall. Wait  plenty of time for the patch to cure.

Clean the interior walls with a sponge that has been dampened with a concrete cleaning agent. Remove the cleanser with a fresh sponge that has been dipped into a bucket of water. Refrain from applying a waterproofing product to the concrete until each wall has dried thoroughly. Use towels to wipe off the walls if you wish to shorten the amount of time that you will need to wait.

Apply A Waterproofing Agent To The Interior Walls

Lay drop cloths along the edges of the basement floor so that the waterproofing agent does not stain the flooring if it spills. Fill a paint tray with the waterproofing product. Dip a thick-napped paint roller that is secured to a roller handle into the tray to evenly coat it. Apply the agent across each interior wall, beginning in one corner of one of the walls. Move the roller as straight as possible so that each concrete surface is covered sufficiently.

Wait for the walls to dry and apply an additional coat of the waterproofing product to ensure that you haven't missed any spots. After the second coat of the waterproofing product has dried, the basement walls will remain dry and damage-free whenever it rains. Apply fresh coats of sealer to the walls if you ever notice that the initial coats have worn off the walls.

For help with bigger foundation repair problems, contact a company like American Mud Jack Inc.