As we’ve shown previously , Bluefield is running regular “Lunch and Learn” sessions for our team while we work remotely. One of our specialists, Keem Semmler, shared a fantastic example of how a simple fix can greatly reduce the incidence of mould in demountable buildings. Most of us have worked in a “donga” while on site, and especially in rainy climates, have experience with working in a mouldy building. An edited transcript of Keem’s share is below.
One of the common faults that I've seen with demountable buildings on sites is the bottom flashing part of the building is not installed. That has a huge impact when they have rain events. If you can imagine when rain water comes down the cladding, it then loops around the edge of the metal cladding and into the 6mm plywood. This plywood typically runs the whole length of the wall from top to bottom in demountable buildings.
So, if the flashing part isn't on here, a capillary action takes place, where it wicks the water up the inside of the walls. The water can’t escape and then mould easily forms in the demountable. So, something as simple as flashings has been a very eye-opening thing, especially in an area where the conditions are quite extreme for Australia; lots of cyclone events and dust and that type of thing.
This is the cause of probably 80% of the issues they're having with demountables on these sites. It's exacerbated by strong wind and rain events. So, keep an eye out for it. And if you do come across a building without this bottom flashing, have a look underneath and see if you can see that ply, because it's usually the middle membrane between the outside cladding and the internal vinyl that they stick up in most of these demountables.
In a cold country, like Canada, they have the same kind of demountables, but they are sometimes very poorly insulated, or not insulated at all. So, in colder countries, you have same kind of problems, both the mould and the fact they're freezing cold.
Apart from that, if there's hot, moist air outside, even if there isn't rain water falling down the cladding, that moisture is going to get sucked up into that ply membrane, because the air conditioning inside is drawing that moist, humid air in. So in Australia, flashings are a huge thing that need to be managed seriously, especially in the Pilbara or North Queensland. Such a simple thing can make a massive impact on your buildings and effect occupants’ health.