Stucco News

Question and answers on Stucco and Plastering
-- July, 2013


Cold joints.

Hi Reggie,
 
“Each plaster coat shall be applied to an entire wall or ceiling panel without interruption to avoid cold joints and abrupt changes in the uniform appearance of succeeding coats. Wet plaster shall abut set plaster at naturally occurring interruptions in the plane of the plaster, such as corner angles, rustications, openings, and control joints where this is possible. "Joinings, where necessary, shall be cut square and straight and not less than 6 in. (152 mm) away from a joining in the preceding coat."

I'm not clear on what it is saying in the red text...

Can you provide a practical interpretation? 

I am trying to find pictures
on how we cut a join in the brown coat.

Here's how we make a join in the finish coat:
cold join in finish 01
cold join in finish 02
A mystic secret is revealed. This wall is too big for all of us to finish in one operation. Here's how we did it with no control joints. First, we put a strip of tape on the brown coat with a level.     We finished and floated the first section, and
    pulled off the tape.
cold join in finish 03
cold join in finish 04
Next, we taped off the edge of the first section, and finished up to it. Looks fine. You cant see the wall was really done in three sections unless you look real close.

http://www.rtbullard.com/prog/dorrier/dorrier.html

The idea is to brown or finish the entire wall
top to bottom, end to end in one operation.
Usually when we  brown a big wall, we plan to work
late to avoid leaving a join. I say join instead of joint.

A join in the brown coat will read through the finish
coat. The finish will hump out over the join.
This has to do with the fact that the join is
less porous than the rest of the wall.

Sometimes, you run out of day before you
run out of wall, or it starts raining, etc. meaning a
necessity to cut a join in the brown coat.


I prefer to make a jagged line in my join for the brown
coat, because it is less conspicuous than a straight line.
I have a good method of doing this. I need to take
pictures next time I have to cut a join in the brown coat.

I need to take pictures for clarity on how this is done,
but the idea is not to leave a ragged hump.

What the red says is that if you leave a join the the
brown coat, for example, between two windows, don't
leave a join in the same place with the finish coat.

If you leave a join in the brown coat between the top corners
of the windows,
and must leave a join in the finish, leave the join between
the bottom  corners of the windows.

It isn't a good idea to leave joins in the scratch coat, either,
particularly on block.