Is it alright to paint over existing lead-based coatings or should they be completely stripped?
The use of lead-based paint coatings in NZ was phased out during the 1960s and early 1970s with some specialised paint products (mainly primers) still having a lead component right up to and including the late 1980s.
Stripping lead-based paint can be time consuming and costly and is not always necessary.
The industry strategy for the last 40 plus years to deal with lead-based coatings has been to paint over the existing coatings where possible. It is not likely you will find lead paint as the outer most coating on a surface, it will however have been encapsulated by subsequent paint coatings that are non-hazardous such as water-based paint. Lead is only dangerous when turned into dust, particles or fumes and painting over the old lead coatings and therefore encapsulating the problem has been an effective strategy.
Sadly, this strategy is likely coming to an end for some exterior painting work as the old paint coats could now be degraded to the point where they are losing adhesion under the new extremely flexible acrylic coating systems. This is why we are seeing much more stripping going on than in previous years. Where the paint coatings are sound, encapsulation can still be a very good option.
It is likely the encapsulation strategy will still be a good one for some years to come for interior paint coatings. This is because these paint coatings are not as flexible as the exterior paint coatings and do not place the old paint coatings under the same strain as seen on exterior surfaces.
If the paint coatings are now blistering, peeling or flaking they should be removed by someone who has been trained in lead paint removal procedures. Of course, any paint coating that is being painted over must be clean, sound and properly prepared before the application of any new paint coating system to interior or exterior surfaces.
All preparation and painting works should be carried in accordance with AS/NZS2311:2017 Guide to the Painting of Buildings and AS/NZS4361.2 Guide to Hazardous Paint Management.
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