Guide Construction Drying and Dehumidification
Sadly, a large number of newly built houses experiences problems with mould. However, how is it possible that empty building shells suffer from water damage even though they have never been inhabited?
- Moisture in construction
- Drying and ventilation for the building shell
- Who is responsible for construction drying?
- Suitable appliances for drying and dehumidification
- After the construction phase
Moisture in construction
The completion of a one family house requires about 10,000 litres of water. The majority of the liquid goes into the cast-in floor covering (screed) and the interior plaster. The enormous quantity of water evaporates slowly over the course of time. Screed requires a period lasting days and even weeks to dry by itself. A bare brickwork has a drying time of up to 12 months in order to become completely dry, concrete needs more than twice as long. In most cases, it is not even possible to let the construction dry naturally by itself due to storm or rainy seasons. Even during the later construction phases such as plastering inner and exterior walls enough moisture could be released to make the windows fog up with condensation.
Due to the heat-insulating layer in the walls water vapour and condensate is barely able to escape from the building. As soon as the roof and windows are added, air change is not as easy anymore, the building must now be dehumidified, ventilated and heated appropriately. Otherwise, mould will become a problem, seeing that it infests the drywall and causes rusting, odour and mildew spots on the walls. In the long run, mould is not only hamful to health but also deteriorates building material and heat insulation.
Where does moisture actually come from?
- Exhalation from plaster, screed, mortar and concrete
- Damp building materials and materials retaining water
- Moisture content in lacquer, paint, mortar, glue
- Construction sites in winter: thermal bridges
- Snow, frost, rain, natural humidity
- Insufficient ventilation and heating
- Condensation water with low temperatures
- Uncovered crowning
- Missing roof drainage and heat insulation
- Ignoring drying periods and minimum required ventilation
- Water damage (groundwater ascent, flooding)
Developers are often under pressure: Future residents have terminated contracts for their old homes and want to be done with the move as soon as possible. Winter season is coming and costs must be kept as low as possible. Summer months and rain periods also play an important role. The constructor should not rush though and give the building enough time to dry properly, perhaps even with electric devices such as infrared heaters and blower fans.
Drying and ventilation for the building shell
As mentioned before, natural drying takes a long time. A freshly poured concrete slab will increase relative humidity to 98% (at room temperature) half a year later. If the appropriate drying time is not adhered to for financial reasons, electric construction drying (consistent heating and ventilating) can help. Particularly if no heating system has been installed yet during early construction phases, a portable heater is a great alternative. Within a few days the indoor climate improves considerably. The costs for electric construction heaters are moderate. The drying time is about 2 to four weeks depending on the present humidity level.
You can see that proper construction drying prevents excessive spendings at a later point in time to save the building. If you decide in favour of purchasing the device rather than renting it, you can make use of it in the future. Infrared heaters for example can be used in the winter.
Benefits of electric drying:
- Shortened drying time
- Portable condensation dryers
- Huge capacities
- Operate even under low outdoor temperatures
- Professional units with minimised operational hours
- Acceptable power consumption
- Eliminating water damage
- Large appliances available for rent, delivery directly to the construction site
Even before ventilation systems are applied to new constructions, invisible mould damage can occur. Natural ventilation by intermittent ventilation on a daily basis reduces humidity, but is often not enough. Furthermore, manual intermittent ventilation can only be done if workers are present at the construction site, but not at night. On hot and humid days with a high moisture content in the atmosphere, vapour cannot escape. That is why we recommend the use of our professional wind machines for construction sites.
Who is responsible for construction drying?
For the most part, structural damage is caused by water. If the construction is done by an external developer or general contractor, they are responsible for the drying of the building. The company is obligated to deliver the building ready for occupation and free from defects, meaning dry and free of mould. Any costs incurred are covered by the developer / builder (unless recorded otherwise in the service contract) or other company that delivers the turn-key building. From time to time, these companies will try to obligate the building owner to deal with the construction drying. An independent expert should take a look at the small print before you sign the contract.
Repairing water damage and mildew spots is expensive, complex project that can be prevented with proper construction drying. Dryers are usually needed before the start of the interior work and sometimes in later phases as well. The builder should frequently check humidity levels during all phases of construction. Hygrometres are available at low prices and measure humidity in a fast, reliable way. The builder must notify the employed construction company immediately after detecting wet bricks and walls to prevent consequential damage on the brickwork. The constructor is responsible for any rectification of the defect and the incurred costs. If the constructor does not react to the notification in an appropriate space of time, the building owners can order the required dryers by themselves and claim compensation for the expenses. In case of problems and disputes concerning assumption of costs and responsibility, get in touch with a lawyer.
An authorised expert employed by the building owner should check the construction drying with measuring devices. Defects in construction can also occur beneath the surface, meaning they are not visible to the naked eye. Before acceptance of work at the latest any possibility of invisible damage caused by moisture and mould should be ruled out. Leakage is detected by the Blowerdoor test. In case of moisture and mould the building owner can decline the final acceptance due to defects.
Upon acceptance of construction work any responsibility will be transferred to the owner.
Suitable appliances for drying and dehumidification
What can our electric appliances do for the construction drying business?
- Humidity removal of several litres per day
- Refurbishment after water damage
- Drying screet
- Drying timbre without burning
- Permanently installed and portable options available
- Exceptional heat output even under 15°C outdoor temperature
- Acceptable power consumption
- Great performance and operating life
- Easy to clean and maintain
- Air filters prevent mould and foul odour
Drying with infrared heaters is an ideal option for ideal, draughty construction sites. Without any heat-up phase the device emits heat, so energy costs are acceptable. Depending on the appliance and IP rating the heaters can be used indoors as well as outdoors. Portable heaters are used for plasterwork or water damage. The versatile infrared heaters also help with the workers’ health, since they fight low temperatures which might cause sickness. Buildings with a lot of draught are particularly hard to heat in conventional ways. Traditional radiators heat up the ambient air which takes quite a lot of time to generate a pleasant overall temperature in the room. Infrared heaters however do not heat up the air, instead they heat up the surface directly, for example the wall or human skin. Especially short wavelength IR-A radiation do not lose any heat energy by air movement. Even strong draught will not impact them, instead they constantly deliver the same performance. Heaters with an IP code rating also provide electric safety during rain and snow. The surface treatment of our outdoor models ensures the devices are weatherproof.
Infrared drying and its benefits
- Infrared heaters with a coverage of up to 80m2
- IP code IP67 (protected against dust and water ingress, powerful water jets and immersion of water up to 1m depth)
- Energy-efficient: no preheating phase thanks to infrared short wavelength technology
- No air circulation, appliances do not raise dust
- Versatile use: in winter, on balcony, in garage, basement etc.
- Easy transport of portable devices, or permanent installation in a fixed place
- Includes temperature-resistant cable with silicone or rubber insulation
- Weather-resistant housing
- Service life of the heater tubes lasts up to 5000 hours (10 – 15 years average usage)
- Maintenance-free, no emission, easy to handle
- Adjustable angle (example): +/- 30°
Our creoven range also includes electric fan heaters. However, these appliances are not suitable for industrial areas and construction sites, they are designed for private use at home only.
Wind machine Speed 40 by CasaFan
Our product line features industrial floor fans (wind machines) and barrel fans with a performance of up to 15,650 m³/h. The revolution speed can be regulated in different steps or customised with a step-down transformer. The robust portable devices are usually equipped with a practical carrying handle and rubber feet that prevent tilting over. Some models are even designed to be mounted to walls or suspended on chains. Beginning with the protection code IP55 the fans are protected against water jets and can be used outdoors. However, you can also use it inside your home at a later point without any problems. An insulated cable (length up to 2.5m) often feature a plug for easy set-up. The lead wire is coming from the backside of the protective grille in most cases. The fans can be inclined at an adjustable angle, quite a few appliances feature an oscillating mode.
Industrial fans in our creoven online shop with overheat control are suitable for continuous operation and withstand the high mechanical stress on construction sites, in industrial and commercial environments.
After the construction phase
Our products can be used even long after residents have moved into the house, because occupants increase humidity levels. Residents (meaning humans and pets alike) and their day to day activities release several litres every day in occupied buildings. Taking a nice and warm shower, cooking a delicious meal and naturally respiration all contribute to indoor humidity. Saline dehumidifying granules and saline dehumidifying plastering are not enough to completely dry damp walls.
Dehumidifier Albert is ideal for dehumidification of indoor spaces with up to 70m².
Albert features a moisture-sensitive, digital hygrostat and allows you to adjust your desired humidity level between 30 – 80% on a handy rotary switch. Indoor humidity should not exceed 60%. A certain moisture content should remain, otherwise dry air affects the human mucosa and certain types of timber. In order to prevent damage on precious furniture the process of humidity control is customised individually. Once the desired level is reached, Albert automatically turns off. This modern dehumidifier is further equipped with a de-ice sensor for room temperatures below 5°C, a night mode and a timer. The integrated water tank holds 4.6 litres and requires manual draining. The maximum daily capacity of the condensation dryer is 20 litres. Albert can be connected to a draining hose to discharge water directly into the drain.
Nevertheless, this appliance is not designed for outdoor use or draughty construction sites. These areas call for professional dehumidifiers that are rated with a protection code against water ingress and can be used continuously over extend periods of time. The professional devices usually come with an attached hose that drains off condensed water directly which saves workers from having to empty a water tank on a regular basis. Construction dryers can be used around-the-clock without human intervention.
We also offer efficient purifiers for removing pollution from the air at home in rooms with up to 80m² / 200m³ size.
With as much as five different operation modes the powerful air cleaners purify ambient air from particles, making them an ideal accessory in households with people suffering from allergies. The HPP and activated carbon filters kill germs and bacteria, remove pollutants, odours and mould spores.