Exterior Blistering Exterior Paint Solution

Blistering: Blistering is the formation of bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface.

Possible Causes:

Painting in direct sunlight or on a surface that is too warm, especially when applying a dark-colored solvent-based coating.

Application of an oil-based or alkyd paint over a damp or wet surface.

Excess humidity or other moisture escaping from inside through the exterior walls (less likely with latex paints, which allow water vapor to escape without affecting the paint film).

Exposure of a latex paint film to excessive moisture in the form of dew, high humidity or rain shortly after the paint has dried, especially if there was inadequate surface preparation and/or a lower quality paint was applied.


First, determine whether or not the blisters go all the way down to the substrate. If they go down to the substrate, the problem may be due to moisture coming from inside. Take steps to remove the source of moisture, if possible. Repair loose caulk and consider installing vents or exhaust fans. If the building has wood siding, install siding vents in areas where blistering has occurred. Remove blisters by scraping and sanding, prime any areas where bare wood shows, and repaint. If the blisters do not go all the way to the substrate, the problem is probably not related to moisture coming from behind. Rather, the blisters are likely from painting a warm surface in direct sunlight or exposing the paint film to excessive moisture. In any case, sand, scrape and then prime any exposed bare wood. Coat with a top quality acrylic latex exterior paint.

Exterior Painting – Frequently asked questions

Can I paint over aluminum/vinyl siding?
Yes. Always make sure the surface is cleaned to remove any chalk or dirt. Never apply paint that is darker than the original painted surface on vinyl siding.

Do I need to wash my house before I paint?
Yes. Surfaces must be clean before painting. Thoroughly wash with a house cleaner and water solution, making sure to remove any and all mildew. Rinse and allow to dry.

How much paint do I need?
Be sure to utilize our Paint Gallon Calculator in the Project Planner section to help you determine how many cans to buy for your next project.

To achieve one-coat coverage, paint should be applied at a maximum of 400 square feet per gallon. Rough or textured surfaces may require more paint. On these areas allow for 25-30 square feet per gallon. Some bright colors may require multiple costs to achieve sufficient hide.

How do I apply the paint?
When using more than one gallon of the same product, mix the gallons together to insure color and sheen uniformity. Two coats of this paint will provide maximum protection.

How do I paint shingles & shakes?
Shingles offer natural breaking points, paint in a vertical direction.

How do I care for freshly painted surfaces?
We suggest not washing your newly painted surface for at least 30 days. After that time, dirt and stains may be removed using a mild, non-abrasive cleanser and water.

I have never painted the exterior of my home before….?
When painting the exterior of your home always start with a clean surface; paint one side of the house at a time, starting with the highest point; apply a full even coat to one side of the house at a time and always paint the trim last.

What conditions are best for painting my house?
Generally you should only paint when the surface is between 50F and 85F. High temperatures cause the water in the paint to evaporate too quickly, while low temperatures prevent latex from covering properly. Always avoid painting in direct sunlight, strong winds, or when rain is expected within 8 hours.

What tools do I need?
Depending on your project and the type of structure you are painting, paints may be applied with a nylon/polyester brush, a paint pad or spray unit.

What is the proper way to use spray equipment?
It is always safe to operate spray equipment with safety cautions. Use respiratory and eye protection. All spray units are different and it is important to follow the manufacturer’s instructions carefully.