Details, Details, Details: Control and Expansion Joints

Over the last several weeks I have discussed a lot of different details that should be completed with the installation of Stucco or EIFS.  Today I am going to discuss control & expansion joints.

It is important to understand why control & expansion joints are needed in the first place.  Traditional stucco or hard coat stucco is made up of several different components, one of those being the hard coat itself.  One of the main properties of hard coat is cement.  As cement cures, it tends to shrink.  Cracking can develop as a result of the shrinking process.  Control joints are installed to help reduce the cracking.

Expansion joints are installed where structural movements are anticipated in a building. A common area for them to be installed on a 2-story residential home is at the floor line of the second floor.  In wood construction, this area will contract & expand during the first year after the building is constructed.

Expansion & Control joints are commonly installed on Commercial projects.  They are less frequent on Residential projects even though Stucco & EIFS manufactures require them.  Control joints are required to break up large, continuous walls (if a wall area is larger than 144 SF, control joints should be installed).  Expansion joints are required at floor lines or where structural movement is anticipated.

The easy reason  that they have never really caught on in residential construction is the fact the wall areas tend to be smaller and homeowners object to the way they look aesthetically and they are prone to water intrusion issues.  The truth is, even though wall areas tend to be smaller, a lot of residential homes have walls exceeding the 144 SF minimum without a break such as a door or window.  Also, control joints can be installed in a way that does not deter from the aesthetic appeal of the building.

Control & expansion joints are an essential detail of any Stucco or EIFS system.  When installed properly, they will help both cladding systems function correctly.  When they are omitted, problems can develop that may affect the integrity of both systems.