Excellent Exterior Paint Selection

An important decision to make before undertaking the task of painting the exterior of your home is whether to use an oil based or waterborne paint. This is a debate that has been going on since the two paint types have been on the market, and there have been strong proponents on both sides, but it’s becoming clear that more and more painting contractors and homeowners are choosing waterborne acrylic paints over oil based paints when it comes to covering houses’ exteriors.

Oil or solvent based paints have been around for decades longer than waterborne paints, and they have earned a reputation as being a durable, weather resistant and appropriate option for exterior projects. In the painting world, there are some circumstances in which oil based paints are superior to their waterborne counterparts, such as the painting of cabinets and furniture. These alkyd based paints create a very durable coating and stand up well to constant handling and cleaning; but the technological advances in the quality of waterborne acrylic paints has made it an easy choice for painting the exterior of a house.

The main reason exterior painting contractors are recommending acrylics to alkyds is the difference in flexibility and permeability. Oil based paints, while being very durable, are also inflexible and unable to move with the inevitable expansion and contraction undergone by exterior siding and trim. The end result of this inflexibility is cracking and peeling in the finish. Waterborne paints tend to move and stretch with the wood exterior as it expands and contracts with moisture levels, and are less likely to fail in this way.

Solvent based coatings also create an impermeable vapor barrier, and do not allow moisture to pass through. At first, this may seem like an advantage. The impermeable qualities of oil based paints do a great job of keeping wet weather on the outside of the house. The problem with an exterior vapor barrier is that water vapor on this inside of the house, generated for example by cooking or showering, will try to escape to the outside through the walls. Since the oil paint will not allow the vapor to escape, the vapor pushes against the backside of the cured paint, separates it from the siding and what’s left is bubbling and peeling and an ugly exterior. This is one of the most common reasons for paint failure and painting contractors are constantly called back to fix paint jobs for this reason.

Another good reason to use waterborne paints rather than solvent based is the negative effect of the alkyds on the environment. For this reason, the entire painting industry is moving away from oil based paints and stains, and some predict that in a decade or less water based coatings will completely replace their oil based competitors.