Rust stains on stucco

Causes

Hairline cracking in the stucco admitting moisture causing corrosion of the reinforcing mesh 

Listed under: Exterior, plaster and fibrous plaster, stucco, stains, cladding, walls, moisture, durability, corrosion, rust, leaks, wall cladding, stucco wall cladding

Cause

Hairline cracking in the stucco admitting moisture causing corrosion of the reinforcing mesh 

Repair

  • if the construction work was completed within the last 10 years, call the original builder back to make the repairs. Homeowners can take action for up to 10 years after building work is completed if implied warranties set out in the Building Act have not been met. These include requirements that work be carried out competently and with reasonable care and skill. The reinforcing mesh of a stucco cladding should not be corroding within 10 years of construction (assuming the coating of the stucco has been properly maintained by the homeowner and remains waterproof)
  • if the work was done more than 10 years ago or the builder is no longer around, consult an experienced registered building surveyor for advice on the options available
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage a building surveyor with good experience in weathertightness issues
  • homeowners should not attempt to make repairs themselves. Inappropriate work here could impact the weathertightness and insurance cover of the home
  • if the problem is widespread, recladding with a different cladding material should be considered. If the stucco cladding is less than 15 years old, and/or the intended new cladding is not comparable with stucco, a building consent will be required

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