I have water seeping into my basement where the mortar has eroded. Is there some sort of waterproofing I can put on before the new mortar, or is there a type of mortar that is waterproof? Any info would be greatly appreciated.

  • Searching for "basement water" -- out looking at the Related column at right if you are seeing this through a browser -- find a number of similar questions. One of those may answer your question to. If not, you might want to clarify why your case is different from those.
    – keshlam
    May 30, 2016 at 21:36
  • 3
    Well if it's actually seeping through the walls you need to fix the problem from the outside and not the inside, else you're not actually fixing anything, you're just covering it up.
    – cutrightjm
    May 31, 2016 at 3:51
  • If it really is just leaking thru holes in mortar (unlikely, per other comments), then get some hydraulic cement and follow the instructions on the bag/box for use. May 31, 2016 at 15:37

1 Answer 1


Cement and mortar are not inherently water proof. Water penetration into the basement is probably not the cause of eroded mortar but instead indicative of a more serious problem stemming from the outside.

A complete fix will involve digging up the area outside the foundation, applying proper water proofing, installing weeping tile (or replacing) and drainage, then replacing the soil.

You will probably find that this is not a DIY job.

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