This story covers some of the problems you may run into with existing exterior surfaces and how to cure those problems before you repaint.
Alligatoring can be caused by:
-- Applying alkyd enamel over a more flexible latex primer
-- Applying the top coat before the primer dries
-- Oil-base paints aging and undergoing temperature fluctuations
-- Remove old paint with a scraper or heat gun. Sand the surface and prime it with high-quality latex or oil-base primer, then finish with a top-quality exterior latex paint.
Chalking can be caused by:
-- Low-grade, highly pigmented paint
-- Using interior paint on an outdoor surface
-- Scrub off as much of the chalky residue as possible with a stiff bristle brush and rinse thoroughly.
-- If noticeable chalk is still present, apply high-quality oil-base or acrylic latex primer, then repaint with a quality exterior coating.
-- If little or no chalk remains and the old paint is sound, no priming is necessary.
Paint incompatibility can be caused by:
--Painting latex paint over more than three or four coats of oil-base paint
-- Completely remove the flaking paint and sand and spot-prime where necessary. Repaint with a top-quality latex exterior or oil-base paint.
Peeling can be caused by:
-- Moisture seepage through uncaulked joints, worn caulk, leaks in roof or walls, or leaks through interior walls to the exterior
-- Poor surface preparation
-- Low-quality paint
-- Applying oil-base paint on a wet surface
-- Earlier blistering of paint
-- Try to eliminate the source of moisture.
-- Remove all loose paint with scraper, sand rough edges, prime, and repaint with a high-quality acrylic latex exterior paint.
Cracking and flaking can be caused by:
-- Low-quality paint with poor flexibility
-- Thinning or spreading the paint too thin
-- Poor surface preparation, especially omitting primer on bare wood
-- Painting in cool or windy conditions, which can make latex paint dry too fast
-- If cracking stops above the substrate, remove loose or flaking paint with a scraper, feather-sand the edges, prime any bare spots, and repaint.
-- If you can see the substrate through the cracks, remove all of the paint, then prime and repaint with a high-quality exterior latex.
Lapping can be caused by:
-- Failure to maintain a wet edge when applying paint
-- Paint from unpainted to painted surface.
-- Plan for interruptions at a natural break, such as a window, door, or corner. Alkyd paints generally hold a wet edge longer than latex paints.