Problems with Bubbling Paint?

Do you having bubbling problems? Does it seem impossible to fix? Have you gone as far as to spend money with multiple contractors? It could be that your problem isn't actually so rare.

Due to the temperature differential between a home's interior and exterior, a sweating process occurs and causes condensation to develop in between the partitions. The best example of the process is to look at a window without a storm window on a cold day. Moisture condenses on the inside of the windowpane and you can write your name on the foggy glass. It is the contrast between low exterior and a comfortable 68-70°F interior temperatures that causes the vapor to condense on the inside of the cold glass. Most homes that experience paint failure and/or cedar bleed due to trapped moisture release are heated by forced hot water systems. Homes with hot air and electric heat systems also encounter the problem, but it is usually not as severe. In general, the forced hot-water heating pipes are commonly positioned at the base of the interior surface walls on each floor of a dwelling. The water in those pipes is normally heated to 180°F. The temperature differential between the inner wall and the exterior substrate on a cold night can be as much as 160-180°F - a condition lasting throughout a six-month heating season. During that time, heated air condenses into water vapor inside wall cavities. You can readily see what happens to the interior window surfaces with a 68-70°F temperature differential, so you can imagine what happens between wall partitions with a 160-180°F differential!?

Moisture problems are most common on surface areas that are interior-heated and receive a large amount of sunshine. Areas shaded by shutters, blinds, eaves or soffits will usually show little if any paint failure or cedar bleed, since the absence of extreme heat differentials minimizes the moisture accumulation and drawing effect. As a result, the side of the house that rarely receives direct sunlight will commonly show less paint/stain failure due to unwanted moisture release.

These problems occur in new and old homes alike. However, building code wasn't nearly as stringent in the past. As time goes on expectations about moisture and thermal envelopes become more and more strict because of emphasis on energy efficiency and mold/mildew.

Water vapor diffusion is a process by which water vapor spreads or moves through permeable materials caused by a difference in water vapor pressure. The materials used in building envelope should limit the entrance of vapor into envelope materials on one side and enable drying of envelope materials on the other.

A vapor barrier or vapor diffusion retarder is a material that reduces the rate at which water vapor can move through a material. Vapor diffusion retarders help control moisture in thermal envelope. In cold climates (where passive and low energy buildings are usually built) on the interior (warm in winter) side of thermal envelope. Properly installed vapor barriers are especially important for constructions that are less resistant to water or lose their thermal properties when the become wet (e.g. wooden construction, mineral wool, etc.). Nevertheless, brick or concrete constructions should also enable drying of the walls which means that layers of materials should be placed in order allowing vapor from the inside of the building to easily "travel" from inner to outer layers any finally evaporate.