Why your exterior paint is peeling off

“The peeling is often caused by water, which has seeped beneath the paint causing cracks that keep multiplying. You can always paint over an area where paint has peeled off. But paint will continue to peel off until the source of the problem is identified and eliminated.

“Instead of painting over the crack, this should be treated as a symptom and further investigations should be carried out to avoid worse damage,” Bigambo advises.

Blistering
Usually the peeling paint will develop paint blisters, which may appear suddenly or gradually after painting. When blistering occurs, let the paint dry, then cut open each blister and remove the peeling paint.

If you can see the plaster or stucco after removing the paint, the problem was most probably caused by moisture trapped inside the wall; if you can see a previous coat of paint; the problem resulted from applying the topcoat before the undercoat has thoroughly dried.

Ronald Atwiine, a construction engineer, cites wood joints at window and door sills as some of the most susceptible area because by nature, they retain water and take longer to dry off.

To prevent the end grain of window and door frames from sucking up all that water it is advisable to seal them with a primer. “Scrape sand and recoat these highly vulnerable areas as soon as peeling paint begins. To reduce the problem by applying a water-repellent preservative to the bare wood to slow moisture penetration,” Atwiine recommends.

Gutter
Another problem area is the trim near the ground, which gets splashed by water from roof and the gutters.

“To prevent it from absorbing water and eventually peeling, maintain your gutters to prevent any leakages, keep bushes trimmed back from the house to promote drying, and fix peeling areas as soon as they appear,” he adds.

Poor maintenance
Another reason your paint could be peeling is poor maintenance. Make it a point to inspect and repair peeling areas annually because it stops localised peeling paint and keeps it from spreading.

Bigambo cites bad painting conditions as another major cause of peeling paint. Conditions such as painting over a dirty surface will lead to poor adhesion.

Rushing the drying times
Paint sometimes feels dry to the touch before it has hardened. A second coat applied too soon can soften the first and create a weaker bond. The labels on paint cans specify drying times, but humid or cool conditions can lengthen them.

Choosing the wrong paint
Generally on the exterior, you can safely cover oil paint with latex, but not vice versa. In addition, stick with the same brand of primers and topcoats, because some primers and topcoats are not compatible.

As insurance against future paint problems, ask the paint dealer to write paint specifications for your project, including the brand and type of paint.

Type of wood
Although this is less common, if individual siding or trim boards peeling off on your home while others nearby do not, examine their grain pattern. Some types of wood do not hold paint well.
Wood used for siding and trim usually has a vertical grain pattern; that is, the tree growth lines in the boards line up close together. Moisture will affect wood cut this way as much as it does flat-sawn boards, that is, boards with wide grain lines. The surface of flatsawn wood moves so much that paint will crack and peel after only a few years if it is put in an exposed spot.
Replace peeling paint flat-sawn boards with boards that have vertical grain, or sand all the paint off and coat them with a paintable water repellent before priming and repainting. The water repellent might stabilise them enough so that they hold paint longer. Use a primer over bare wood.

Some people do not, or substitute a thinned paint for the primer. That is not good enough when you want a high-quality job. Primers are specially formulated to seal and adhere to bare wood and other materials. They aren’t cheap paint. A good one should cost almost as much as a topcoat. (Source: home repair)