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What Are the Causes of Wavy Exterior Siding and Walls?

When a house is brand new, all of the siding and walls are straight as an arrow. Over time, however, the siding, or the walls, may have developed bulges or concave areas, making it look wavy.

All houses sag with age; notice how the siding is buckling due to sagging.

When a house is brand new, all of the siding and walls are straight as an arrow.  Over time, however, the siding, or the walls, may have developed bulges or concave areas, making it look wavy.

There are some definitive reasons for this, and knowing and understanding the reasons is the first step in correcting the problems. 


Temperature Changes

Most materials expand when heated and contract when cooled.  In a state such as Michigan or Wisconsin, where the temperature fluctuations between winter and summer are great, the constant expanding and contracting will eventually warp the siding, causing it to look wavy.

There is really no way to prevent this; it is normal for very old siding to look wavy. 


Improperly Installed

Understanding that materials expand and contract due to temperature fluctuations, the siding itself has to be installed correctly to compensate for the expansion/contraction cycle.  If the aluminum or vinyl siding was pulled too tightly against each other when installed, the contractions pull it even tighter, causing it to buckle.

If panels were used, such as T-111, the panels can not be butted too closely or tightly together, but rather must be installed with a little "breathing room" of no more than 1/8 inch between each overlap joint to allow for the expansions and contractions. 


Sagging House

Over the years, house foundations start to sink into the ground and walls develop sags.  These sags then cause the siding to buckle, and waves start to form.

This is a normal part of the aging process; many very old houses even had their foundations removed and replaced.  If a relatively new house starts to sag, structural problems may be present according to Bob Vila, requiring qualified attention to the matter.

About the Author

Tony Oldhand has been technical writing since 1995. He has worked in the skilled trades and diversified into Human Services in 1998, working with the developmentally disabled. He is also heavily involved in auto restoration and in the do-it-yourself sector of craftsman trades. Oldhand has an associate degree in electronics and has studied management at the State University of New York.

Photo Credits

  • old house image by Bart van der Putten from Fotolia.com
  • old house image by Bart van der Putten from Fotolia.com