Vinyl Siding Terms & Definitions


When it comes to selling vinyl siding, the most commonly asked question is….how thick is it?   Yes, the thickness of the panel is an indicator as to the quality of the siding, but it is only one characteristic.  Most vinyl manufacturers offer at least three horizontal panels.  Generally the economy panel is 0.040 inches thick, the higher quality panels typically run from 0.042 to 0.048 and there are a few over 0.050 thick.   Most people do not realize how small a difference there is from 0.040 to 0.048.  So, using thickness alone to characterize a panel is somewhat misleading.


The second most encountered question….will it fade?  The answer is yes.

The ability to resist color fading is directly related to the amount of titanium dioxide and other stabilizers added to the vinyl siding during its manufacture.  There is a developed ASTM standard by which fade can be measured and the manufacturer’s warranties take this into account.  The idea is that the color will fade somewhat over time, but the change should be gradual, uniform, and not “excessive”.  The warranties are generally pro-rated and will vary as to what you may expect for panel replacement and payment of labor.


Diagram of the profile of Vinyl Siding


Standard horizontal vinyl siding is designed to mimic the appearance of wood lap siding.  The individual panels cover a height of 8 to 14 inches, (depending upon the profile), by 12 feet of horizontal run. The Return (butt/locking leg) on the bottom of each panel engages the Lock at the top of the next panel.  Each panel is secured to the wall by placing nails in the slotted Nail Flange.  The design and construction of the lock and nail flange adds greatly to the overall strength and rigidity of the panel.  Thicker panels with larger locks and double walled nail flanges will have better wind resistance, will lay straighter on the wall, and will be less likely to warp from temperature fluctuation.


Projection (butt height) is the measure of how far the folds in the panel stand out from the wall.  An economy panel may project only 3/8 inch, a higher quality panel will have a projection of 5/8 to 3/4 inch. Greater projection adds rigidity to the panel, and gives the panel a more realistic appearance by providing more of a shadow line.