The fibrous structure is engineered with microscopic pores that readily allow moisture vapor to evaporate but are so small that bulk water and air cannot penetrate. Siding, whether it's vinyl, wood, stucco, brick, or composite, does not completely prevent air and water penetration. R-Value ratings for insulation are only maintained as long as the air within the insulation stays still and dry. As air infiltrates, it causes changes in temperature that require heaters or air conditioners to work harder. Constant temperature fluctuations also reduce comfort levels.
Occupants feel too cold or too warm.
Reducing air infiltration, increases a home' s comfort factor. Insulation can help increase the R-value, but it is only marginally effective in reducing air infiltration. Adding thicker insulation won't solve the problem. Stopping air from getting in will. The tighter a home, the more comfortable and efficient.