Ask the pros-June 2010

By Reggie Bullard



What are screeds ?

Criss cross screed
An example of horizontal and vertical screeds.
A screed is set horizontally at the top between the corner strips. Another screed is set between the horizontal screed and the metal weep screed at the bottom. A horizontal screed is being set in the middle.

Vertical screeds
I used arrows to show vertical screeds set about 5 feet apart between the back of the frieze board and the weep screed at the bottom. Now you see why weep screeds are
called screeds. A straight edge is used for this, either a rod or even a straight board. There are a lot of methods for doing this.I'm just trying to provide an overview. The end result is to get the wall straight, or a curve, if you want a curve

rodding between screeds
Wall is then filled and rodded off in between the screeds.  In concrete work, a straight edge is called  a screed, and rodding off the concrete is called screeding. In plastering, the straight edge is called a rod.

Brown coat finished
    The other side is done the same way. Here, the corner strip is removed preparing for the finish coat. The walls are dead straight. The most important step in plastering is the brown coat, and straightening the brown coat. The finish will follow the contour of the finish, whether it is straight or looks like the ocean. The idea of the finish coat magically making everything look right doesn't work.
     Larger walls are more complicated, but the principle is the same. The screeds illustrated here are called "soft screeds", because the are set and filled at the same time. It is OK in inside plastering to let the screeds set up overnight, as long as care is used to fill in between the screeds, and not over the screeds. A screed in cement if left overnight
will show a hump in the finish coat. I plastered a hallway in a school in Maryland many
years ago with cement plaster, that you can see a hump where every screed was through the finish. It got late on me, so I left the screeds to set up overnight. I'm not going to tell you where it is, but my plaster chalk boards and stucco ceilings still look fine.

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