In this blog we are talking about PVA as an encapsulant of asbestos.
PVA stands for Polyvinyl Acetate and is a glue-like substance, best known as a wood glue, white glue or school glue.
It is a safe glue and doesn’t burn your skin. It is easily washable and is water based. It used to be used in the construction industry all the time because it was cheap, easy, doesn’t make a mess and can be cleaned up easily.
The problems with using PVA as an encapsulant
By the time we entered the industry in 2000, you were only allowed to use it under certain circumstances but contractors still tried to use it all the time within their asbestos enclosures to basically stick everything down. If they had removed a load of asbestos insulating board and there were asbestos fibres floating in the air, the quickest and easiest way to reduce the fibre levels, is to do a quick vacuum and apply PVA spray to everything, including the sheeting. The mist and fibres in the air will fall together and it will all stick and dry.
Let’s be clear – PVA is a cheat’s way. When the consultant runs the air test, it is more likely to pass because everything is stuck down. However, if future workers disturb the PVA, those fibres could be liberated into the air again.
It’s one thing using PVA on the polythene which would be removed as part of the destruction of the enclosure but it should not be used on other surfaces.
Imagine you PVA the brickwork in a boiler room. Everything sticks to it and it passes the air test but over the next few weeks, months and years, the PVA degrades. It’s more susceptible than other encapsulants and that’s why it is no good for this scenario.
If you go back to your school days can you remember using PVA glue on your hands and then peeling it off? When it is used in asbestos enclosures it is watered down so it is sprayable. As a result, it is weaker and can be easily removed with some water and slight rubbing and it becomes flaky. You cannot build layers with it. It dries see through, leaves the surface shiny and you cannot see what has been encapsulated.
The problem with PVA is it degrades over time and bacteria and fungi can degrade it whilst in situ. If you think about the types of place you might want to spray with PVA, like boiler rooms, they are susceptible to heat changes, condensation and water penetration through walls so PVA is definitely not the go to material to use for sealing anything to do with asbestos.
Can PVA be used as an encapsulant on asbestos works?
Even using it on asbestos works, is frowned upon. It can be used as part of the clear up process. If there is lots of debris and dust being generated you are on occasion allowed to do that kind of seal but that is the only situation.
Other than this, PVA should definitely not be used as an encapsulant. PVA will not add any sort of protection to those asbestos materials, not for any length of time and that’s no good if you are trying to manage your asbestos. That is when you need to use sprayable vapour barriers.
PVA as a primary seal
Some contractors use PVA as a primary seal, prior to encapsulating asbestos. That can be good because the light spray from the hand sprayers can form a seal before the contractor paint it which is a good risk reduction for exposure. It takes to their boards a bit better sometimes.
What is a good alternative to PVA?
A good alternative would be to encapsulate with proper materials. For example, ET150 is an Asbestos Encapsulation Paint which can also be sprayed or applied with brushes and rollers. The finish isn’t always great as it is thicker than normal paint but you get more of a covering and protection. The vapour barrier paint finishes with a rubber protection. It will take more impact than normal paint and definitely more than what PVA would.
If you have any removal projects question the use of PVA. You might get the certificate you need but in the long run is that what you actually want? Does that suit you and your site’s needs? There may be occasions where it is used but you should question its use.
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