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Re: Problem with Vinyl Lattice Changing Shape

From: rlundgren@elliotwhittier.com
Category: Other/Misc
Remote Name: 206.40.175.51
Date: 20 Jun 2006
Time: 01:13 PM

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Question: I added a 14x16 addition onto my lakeside home in New Hampshire in 1999. While the main house is on a poured foundation, the addition is on poured concrete posts. The open area underneath was covered with white vinyl lattice. Recently I noticed the lattice was buckling out, giving the appearance that the addition was settling badly. After checking with a level, any settling appears almost insignificant. Question: Is it common for vinyl lattice to change shape (expand in my case?). A neighbor said she was warned about using it on her house.

Builders Websource® Answer: Vinyl, while used successfully in many building products, has a relatively high thermal expansion coefficient, which in lay terms, means that it is subject to more physical expansion and contraction over a wide temperature range when compared to other materials, such as aluminum or fiberglass. For this reason, some designers prefer newer fiberglass windows over their vinyl counterparts, particularly where extreme differential temperatures are possible. It's all about optimizing dimensional stability and certain materials respond differently to temperature swings than others. The following chart compares the relative sensitivity to change in temperature of common materials:

We suspect that your lattice siding is not well braced -- and when subjected to the temperature variations in New Hampshire, you're probably also seeing some "shape fatigue" due to thermal cycling. Using a painted wood lattice will provide better rigidity, however, with the added burden of more maintenance and the potential for dry rot.  

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