Moisture and Peeling Paint

Most peeling paint is caused by the moisture. This is particularly true of older homes without adequate ventilation. The problem is usually worst on the walls outside of high moisture rooms, such as bathrooms.

The moisture will migrate through the wall until it reaches the surface of the exterior siding. If that moisture cannot easily escape from the wood, it can push the paint film away from the surface. The problem tends to be worse on walls that get significant exposure to the sun.

When the sun hits the wall, the water expands. On older homes, it is likely that an oil base paint was used at one time. Oil paints do not “breathe”, i.e., allow moisture to move through the paint film.

In addition, on many older homes the overlap between pieces of siding has become sealed over the years. This prevents adequate ventilation of the wall cavity, which in turn keeps the moisture trapped.

Moisture takes the path of least resistance. This generally means pushing the paint film off of the surface. The problem is usually made worse on walls with direct sun exposure. As the sun heats the wall, the moisture vaporizes and expands.

The solution essentially involves improving the ventilation of the wall cavity. This can take several different forms.

One of the easiest is to simply break the seal between the pieces of siding. This may involve removing caulk and the build up of paint. While the gap between the siding boards may be a little unsightly to some, peeling paint is usually more so.

In extreme cases, it may be necessary to insert a small wedge between the boards. This will maintain the proper gap between the siding, and allow the moisture to escape.

Variables in Estimating Paint Jobs

I frequently receive phone calls and e-mails from someone wanting a “ballpark” price for their painting project. They usually give me the size of their house and think that this will be sufficient for me to provide a price. However, there are dozens of variables that must be identified and considered, and the size of the house is not one of them.
I can understand why a home owner might think that pricing is based on square footage. Many painting contractors actually price their work that way. However, unless we are painting the floor, the square footage tells me nothing about the work that needs to be performed.
As a simple example, consider a room measuring 20 feet by 20 feet, or 400 square feet of floor space. Assuming 8 foot ceilings, the walls have 640 square feet of surface area. Four rooms measuring 10 feet by 10 feet would have the same floor area. However, the wall area would be 1,280 square feet. Despite an identical floor area, the smaller rooms would require twice the labor and materials. And if the ceilings in the smaller rooms are 10 feet high, there would be another 320 square of walls to paint. In short, the area of the floor doesn’t provide an accurate measure of the area that will be painted.
Similarly, the floor area provides no information about other surfaces or their condition-the type and quantity of doors, windows, moldings, etc. It doesn’t indicate the height of the ceilings or the type of texture. It doesn’t tell me what repairs or prep will be required. All of these variables, as well as others, must be considered when pricing a painting job.
All things being equal, a painter should be able to perform the same task in approximately the same amount of time on every job. If it takes him 30 minutes to paint a particular type of door at Mr. Green’s, it should take him 30 minutes to paint the same type of door at Mrs. Brown’s. If the estimator knows how long it takes to perform a task, he can generate an accurate estimate by identifying the tasks required and the quantity of each task.
Of course, all things are seldom equal. The door at Mr. Green’s may have more peeling paint than the door at Mrs. Brown’s. Her entry may be two stories high, while his is only one story. Mr. Green may want his walls and ceilings to be the same color, while Mrs. Brown wants white ceilings and forest green walls. These variables will impact the labor required, and thus have an impact on the price.
Because of the variables involved, equally sized homes may require a vastly different amount of labor and materials. And this should be reflected in the price.
When I have explained this to a caller or e-mailer, I am often told that no prep is required, that the doors, windows, and texture are “standard.” However, in this context there is no such thing as standard. A typical house usually has different kinds of doors. And there are nearly a dozen different types of texture common in the Houston area.
It would certainly be easier to give estimates without looking at the job site. But that would be a disservice to everyone involved.

A Primer on Primers

Primers have 2 basic purposes— to promote adhesion and to seal porous surfaces. Primers can be formulated for either purpose, or in the case of many primers, both.

As a general rule, a bare surface should be primed. Surfaces such as wood or masonry are relatively porous, and a primer will promote a more uniform finish.

Primers can also be used to improve adhesion over hard, slick surfaces. (Other methods, such as mechanical abrasion can also be used.)

Specialty primers are used for particular problems or situations. For example, drywall repair clears are used to improve the soundness of damaged drywall. Primer/ sealers are also used to block stains.

It is seldom necessary to prime previously painted surfaces. There are occasional situations where this might be necessary or beneficial, such as when it might be more efficient to primer rather than degloss a surface.