Failure of House Paints from Moisture - Part 2: Controls

The first step in solving a house-paint moisture blistering or peeling problem is to determine the source of the water that is doing the damage.  In the next blog we will examine solutions to the problem.

Outside Water Clues

  • It can occur on both heated and unheated buildings
  • It only occurs on surfaces that can be wetted by rain and dew.
  • It will be most pronounced at edges and ends of boards and where water is held on the surface.
  • It occurs after rain or heavy dew and is associated with a brown discoloration.
  • It occurs below roof valleys and corners where rain runoff from the roof excessively wets the side wall of the house.
  • It occurs below horizontal roof edges and roof valleys where ice dams developed during winter months. Ice dams form when melting snow on the roof refreezes at the roof edge and gutter, dams up the water which penetrates in under the shingles and through the roof boards, and finally runs down into the side wall and behind the siding.

Inside Water Clues

  • Blistering or peeling caused by plumbing leaks. Such damage is not seasonal and is localized.
  • Failure of paint at the gable ends and high on the side walls of a house indicates moisture condensation in the attic and inadequate provision for ventilation to keep the attic dry.
  • Blistering or peeling caused by condensation of moisture vapor in side walls (cold-weather condensation) can often be observed under the following conditions:
  • It is usually most severe on the coldest (north) side of the building or outside unheated rooms such as closets.
  • It is likely to be concentrated outside rooms having high humidity, such as bathrooms, kitchens, or rooms in which water vaporizers are used.
  • The blisters appear in localized areas on the house in late winter or early spring before the spring rains.
  • The damage occurs on wood protected from rain and dew, as well as on wood which is unprotected from the weather.
  • The damage only occurs with heated buildings.
  • The building has not vapor barrier.
  • The building has a humidifier. Also, window frames and sills are badly stained due to excessive water condensation on the inside window panes.

About the Author:

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and building materials, wood decay and degradation, and wood science. Shupe worked as a professor and lab director at LSU for over 20 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the President of the Baton Rouge District of United Methodist Men, and Board Member for Gulf South Men and a Team Leader for The Kingdom Group. He is a volunteer for the Walk to Emmaus, Grace Camp, and Iron Sharpens Iron. Todd is a Men’s Ministry Specialist through the General Commission of United Methodist Men and is in training to be a Certified Lay Minister through the Louisiana Conference of the United Methodist Church.