My house has an abandoned concrete patio at ground level. Previous owner built a 12'x 12' wood deck 14" above the concrete patio. I have rain water getting in my basement where the concrete deck meets the house block wall. I have built a roof over the deck and fixes all gutter issues. I plan to remove a few decking boards, which are parallel to the house and repair the joint between the old concrete deck and the house concrete blocks. My alternatives are:

  1. Place mortar between the blocks and concrete deck
  2. Place mortar and lay a row of brick between the blocks and concrete deck
  3. Clean, apply silicone caulking between the blocks and concrete deck and put bricks on the caulking
  4. Clean, apply silicone caulking between the blocks and concrete deck and put vinyl siding angle between the blocks and ....This angle is 1.5" by 1.5" with a 90 degree angle that is rounded (radius).

2 Answers 2


Sealing that joint is a low-percentage game. The patio probably moves with seasonal changes in ground temperature, and most products will let go after a few years, leaving you in the same position.

I'd do this:

  1. Remove some decking to make access to the patio.
  2. Using a rented diamond saw (chain saw style) or jackhammer, cut 2-3' off the foundation side of the old patio.
  3. Re-grade with suitable soil and slope between the remaining patio and the foundation. The new slope probably wouldn't need to land above the patio if there's a suitable side outlet path.
  4. Reassemble the deck and be happy.

First off, is your basement finished? Can you see exactly where the water is entering into it. If so, you need to fix it.

I like your number 4 solution. I think 8" metal flashing would be better then the 1.5" vinyl angle. Use some roofing wet and dry patch or roofing adhesive to fasten it to the blocks and concrete.

  • Thanks for your reply. The area of the basement that has a wet wall after heavy rain is not finished. Exposed concrete block wall. I'm thinking to solve the problem from the outside first, then consider some kind of coating on the interior block wall.
    – Dave
    Commented Aug 21, 2019 at 12:46

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