Ask the pros-
June 2010

By Reggie Bullard

Block joints show through the stucco.
Block joints
Block joints
Condition 1: Block joints show as humps.
Condition 2: Brick (or block) joint show when wall is wet.
  Thanks for your great site and willingness to answer questions.  I am a
landscape contractor in the great NW.  I hired a sub to stucco a block wall.
 The finish is sound and attractive except for one panel where the joints in
the wall have bled through.  What causes this?  Thanks!

We have eliminated the block joints showing as humps, but haven't competely eliminated the joints showing when wet. Our jobs are far better than the wall in the picture.

I already covered how to eliminate the block joints showing through, by rodding off the wall from side to side, between horizontal screeds. Please click here.

What I didn't explain is what screeds are, so I wrote about screeds. Please click here.

The important steps to eliminating block joint are:

1. Allow the scratch coat on the blocks to set up overnight.

2. Fill the wall out to an honest 3/4"

3. ALWAYS rod the wall side to side and NEVER up and down.

4. Allow the brown coat to set up a week before applying the finish coat.
     In hot weather, 3 days may be enough, but this is critical in cold weather.

The picture in conidition 1 is an apartment building in Reston, Virginia that was stuccoed in the early 70's. I know because I was working close by in that time period. The picture in condition 2 is a well known Washington, DC area restaurant. The sad thing is, the color stucco looks like it was well done, except the brick joints show really bad when they are wet.

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