Brick exspanion jiont

[Rick P. Hamilton]

how to explain a exspanion joint in a brick wall from top to bottom of wall, properly to the buyer.

[Larry D. Kage]

Try this, Rick...and welcome to the board.

http://masonryanswers.com/tech/desig.../movement.html

[Marcel R. Cyr]

Welcome Rick.

And if they still don't understand, show them pictures.

[Bob Elliott]

I was going to look up my report language but I think a good verbal explanation woukld be to compare it to what you see in sidewalks and explain how it prevents cracking by providing relief.

Just saw a good explanation for how volcanoes provide pressure relief for the magma in the earths core (Discovery channel)which may help lead to another layman explanation.

[Marcel R. Cyr]

This may help him here a little.

Shrinkage cracks occur to alleviate internal wall stresses.

Over time, concrete materials have a natural tendency to shrink and to move in response to changing temperature and moisture conditions.
These movements tend to decrease the length of the wall.

The degree of movement is small, vertical cracks form at regular spacings to accommodate this movement if the ends of the wall are restrained from moving.
The cracked wall then acts as a series of separate panels, each with the ability to move slightly without impacting the next panel.


To prevent shrinkage cracks, stresses within the wall must be reduced through the use of control joints. Conversely, horizontal reinforcement can be used to distribute the stresses, which results in more, but smaller, cracks held tightly together.
Control Joints

Control joints are planned vertical wall separations. They basically divide a wall into separate panels, similar to what happens naturally after shrinkage cracks occur.