Does Siding Increase R-Value?

QUESTION:

I plan to install vinyl siding on my house. Will this make my walls more energy efficient?

ANSWER:

Siding alone will have almost no impact on the insulating capability (R-value) of your exterior walls. Even if the siding comes with a backing of rigid board insulation, this polystyrene beadboard is usually so thin and loose fitting that it will increase R-value only minimally.

If your walls have never been insulated, we strongly recommend you blow insulation directly into the wall cavities before installing your siding. This will bring your total wall R-value to about 13. The cost of doing this can vary from a few hundred to a few thousand dollars, depending the size of your home and who does the work.

To raise the R-value by an additional 5 points or so, you can sheath the walls with rigid board insulation before installing the siding.