Expanded or Extruded Polystyrene


Old 06-11-13, 03:00 PM
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Cool Expanded or Extruded Polystyrene

What type of insulation board is most commonly used under vinyl siding? Is one preferred over the other?
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Old 06-11-13, 03:37 PM
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Expanded (EPS) is the usually white stuff that is usually used for coffee cups and meat trays. It has lower strength and less insulation value.

Extruded (XPS) is usually colored and is used for insulation and construction. More strength, rigidity and better insulation.

Since vinyl siding is cheap and it may be used for stiffening somewhat if jammed/attached to the siding, although the loose joints reduce the real effectiveness severely. It may be used as a low cost replacement for covering of the exterior of the home before siding.


Last edited by Concretemasonry; 06-11-13 at 04:09 PM.
Old 06-11-13, 04:06 PM
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How much foam is another question. Here is a related link.
Calculating the Minimum Thickness of Rigid Foam Sheathing | GreenBuildingAdvisor.com

Old 06-11-13, 05:01 PM
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Vinyl siding doesn't necessarily need any insulation under it. Rigid foam insulation or 1/4" fanfold insulation is commonly added when the installers want to go right over clapboard siding or some other type of uneven surface.

If you provided more information about your reasons for wanting insulation you could probably get some specific replies.

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