We're in the process of replacing some deck boards, and are wondering if we should replace a section of the cement block wall. We're also not sure what the best way to go about it is. It's apparent from feeling where the block has deteriorated at the bottom, that it was not attached to the concrete floor. Replacing the block is one option. If we go that route, should we attach the blocks to the floor some how so that the same thing does not happen again?

What I was thinking I wanted to do, was remove the wall W1 in the picture and replace it with a wood post P1 that gets cemented into the floor. Is this a good idea? I don't think the wall is serving any function and all it's doing is keeping water trapped behind it, though I may be wrong?
We're In Minnesota so the snow and freezing temperatures are something to consider.

Deck Wall other side

  • What is the purpose of that wall?
    – DA01
    Sep 27, 2014 at 19:41
  • 2
    From bearing on a patio slab on up, there's nothing shown in the photos that looks much like a good idea. Removing the slab (or a portion of it) and installing a proper below the frost line foundation is the place where good ideas start.
    – user23752
    Sep 27, 2014 at 20:28

2 Answers 2


As mentioned in the comment above, the post which is all you should need on the corner, needs to be mounted on a concrete pier that goes to the frost line for your area. If there are other areas of your deck that are supported soley by a post or block on the slab that will rise or fall as ice forms and melts under the slab, needs to be resupported by concrete piers that go the frost line


If the deck had continuous support from the block wall it may not have any support beam, and you might have to add one as well as the post(s). If the joists were running parallel to the wall then a beam is probably not necessary, but you will still need an extra joist in place of where the wall was.

The posts should have proper footings as well.

Check your local building code for deck footing requirements. They should extend to below the frost line.

If you are lucky, the block wall will have a foundation/footing underneath.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.