14 Oct 2020

Four myths associated with humidity on site

Image displaying construction site
  • Written By

    Ryan Stanley
    London, UK

  • Published in

    London, UK

I’ve been working for Aggreko for over a year, but specialising in moisture control for well over a decade. In that time, I’ve learnt and taught a lot but the complexity of moisture formation in buildings remains unchanged.

It’s therefore no surprise that when I’m out visiting sites that I come across a range of perceptions and levels of understanding relating to this topic. In fact, a number of misconceptions and incorrect information still exists across the market and are causing further damage to sites.

I thought I’d share four of the most common myths that I regularly hear:

1. “Rapid heating will dry the moisture out”

While many believe that vigorously heating a space onsite is the best way to dry moisture, this method doesn’t actually remove the problem. By heating the space, the atmosphere is expanded, drawing the moisture from the materials into the air. Once the heat is removed, it only takes around 48 hours for moisture equilibrium to be restored, as it returns from the air back into the building’s fabric. To correctly deal with the moisture, it must be drawn out of the materials and then removed from the atmosphere with dehumidifiers.

2. “Opening windows and doors in summer will air the moisture out”

Opening the windows to ventilate a space may seem like a logical way to let moist air out a building on a construction site during summer months. However, if the air outside of the building has a higher relative humidity, it actually draws more moisture into the room, worsening the problem. The best practice is to dehumidify a completely sealed room to bring down the interior relative humidity without letting exterior conditions affect moisture levels.

3. “Drying spaces after flooding is the same process as controlling humidification in buildings”

Surface water from flooding can be dried out and removed relatively quickly and takes only a visual inspection to decide whether the problem is mitigated or not. The difference with controlling humidity in buildings is controlling moisture goes beyond surface water. Site and project managers must take into account all of the moisture sources that contribute to free moisture in the building materials, making sure that overall relative humidity is kept at a comfortable level using close monitoring of environmental conditions in the space.

4. “Condensation season is only an issue in the winter months”

Contrary to popular belief, condensation is not only a problem in the winter months. Condensation occurs when cool air meets hot air, bringing the moisture in the warmer part to its dew point where it becomes condensation. Given that air in the summer often has a high relative humidity, condensation, and the moisture it creates, poses problems for construction project managers year-round, not just in condensation season.

As I say, these are common myths and so you’re not alone if you’ve read this and been surprised.

If this is a topic you’d like to find out more about, you can download my latest guide ‘The True Cost of Humidity On Site’ here

Download Humidity Guide