In Wellington, how long an exterior paint will last depends on a number of factors:
- Amount of sun—paint on the north side of a house will usually not last as long as the paint on the other sides of the house because the north is exposed to more ultraviolet light.
- Exposure to the elements—due to Wellington’s unique geography our homes are often exposed to harsh elements such as sand, wind and rain.
- Preparation and quality of the surface.
- Cleanliness of the surface—house paint lasts longer when it is washed regularly to remove dirt and chemicals.
- Condition of the previous paint job—new paint will last longer if the old paint is still in good nick.
- Size and material under the paint—paint usually last longer on thin weatherboards and smaller surfaces because the overall movement isn’t as great. Paint also usually last longer on concrete, brick and some of the newer building materials.
- Quality of the paint.
- Number of coats applied.
- Colour—light colours will usually last longer than dark colours because darker colours absorb more heat so expand and contract more.
The first signs of paint ruination on timber is usually around corners, joints, mitres or ends where moisture is more likely absorbed. Following, are some telltale signs the exterior of your house needs a new paint job:
- Paint that has faded.
Paint can fade due to sun bleaching or water intrusion. If you notice uneven fading, it may be water damage. Or you may simply notice that your home’s colour isn’t as vibrant as it used to be, suggesting it may be time for a paint job.
- Paint that Cracks.
Paint will usually crack if there’s movement in the substrate, also if it’s recoated before the earlier coat was dry or a hard coat is painted over a soft coating.
- Paint that bubbles or blisters.
Signs like bubbling can signal rot, mould or moisture trapped in the substrate. Blistering paint indicates that a heat source is too close. Also, resin bleed can be troublesome in some softwood timbers and cause blistering.
The formation of white, chalky powder on the painted surface often occurs as the paint weathers and degrades under UV light.
- Paint that is peeling or flaking.
The main reason for peeling or flaking paint is incompatibility with the substrate or previous coating. Poor adhesion and flakey paint can also occur if the surface was damp when painted or too long a time was left between coats.
Here’s a cracker test to see how well existing paint is adhering: Make a couple of cross cuts (#) in the paint with a sharp blade. Press adhesive tape over the cuts, then pull up. If paint flakes come off with the tape, the paint should be removed before repainting. If the existing paint is firmly attached, new paint coats can be applied after sanding and a thorough clean.
It is best practice to remove all old paint after every four or five repaints.
Getting the job done right to start with and a little maintenance can add years to the life of the paint on your home.