While the UK may not suffer extremes of cold, our winters can still get pretty chilly as well as damp. When the temperature drops close to or below freezing, as has often happened this winter, there are two good reasons to consider heating indoor construction sites: first, to provide a safe environment for the workers, and second, to dry out damp areas to ensure work is not compromised or delayed.
What's unsafe about cold weather working?
Workers exposed to the cold are potentially at risk from hypothermia, which occurs when body temperature drops from the usual 37C (98.6F) to below 35C (95F). It happens when the body loses heat faster than it can be generated, and can start to occur even when the temperature is well above freezing, especially if the person is damp from rain or sweat.
Although active site workers are unlikely to suffer serious hypothermia, the risks of mild hypothermia are very real. Low body temperature affects how the brain functions; loss of coordination and concentration are typical consequences. When combined with the types of equipment site workers are normally working with, the risk of accidents – including potentially serious ones – is heightened.
Wearing multiple layers of clothing, including ones that will keep the wearer dry as well as warm, will help to counter the impact of the cold, as will drinking regular hot drinks and eating hot snacks. However, within indoor or enclosed environments, it can be useful to provide heating to ensure the risk of accidents is minimised. This is particularly worthwhile if there is also a need to dry out a site.
Damp can cause delays and damage
Moisture within buildings under construction can create serious problems for contractors trying to deliver work on schedule, and even undermine the integrity of the buildings themselves.
Delays typically arise when the drying times, required by processes such as plastering and concreting, are extended due to cold and/or damp weather. Until complete, further work cannot usually be started, resulting in delays that not only cost money but could also affect a contractor's reputation for completing jobs on time. In addition, if excess moisture is not dealt with it can damage other materials used on site. Wood flooring and frames absorb moisture, so will expand and soften, creating rotting and warping that can cause problems during both installation and once the ultimate occupier of the building is in residence. If a concrete floor is not fully dried out it could lead to a catastrophic structural failure.
Temporary heating solutions
Heating cold indoor sites helps solve the problems described above. A range of options for providing heat are available.
Direct fired heaters, which run on propane or natural gas heating, force the fuel vapour directly through an exposed flame to provide their heat. Although they are powerful, efficient heaters and are cheap to run, they have two key drawbacks.
Drawback 1: they can be used safely only in well-ventilated environments, because the flame requires oxygen from the surrounding air to burn and harmful exhaust gases, such as carbon monoxide, are produced.
Drawback 2: they add rather then remove moisture to the air. They therefore offer no solution to drying out damp sites.
With indirect fired heaters, the flame is contained in a chamber which heats the air passing over and around it. The heated air can then be directed to where needed, and is both dry and free of any combustion fumes – perfect for drying out a damp site.
Electric fan heaters, when combined with ducting to keep them from direct contact with damp, are an alternative heat source that, while generating less hot air per unit, can be used in numbers and are very manoeuvrable.
Which heating is best?
The best choice of heat source will vary from one site to another, and on what the heating is designed to achieve. It is important to calculate the cubic space that requires heating, the required temperature, and how easy it is for any heat to escape, in order to determine the degree of heating required.
Heating and drying resources from RVT
RVT has a range of indirect oil-fired and electric fan heaters to provide warmth for workers and/or dry out damp sites.
This case study shows how temporary heating can make the difference between a job finishing on, or behind, schedule.
This heating calculator will help you to assess the amount of heat your site needs, or you can request a site assessment by an RVT expert – who will do the calculation and recommend the ideal solution – completely free of charge!