- The best solution in terms of engineering design and construction engineering for solving the problem with moisture
- Prevents mold due to natural vapor diffusion
- Protects against dew and weather influences
- Structural segregation of thermal insulation and weather protection
- Attractive and large aesthetic design variety
- Facilitates a pleasant living climate in heat or cold
- Greater safety in a fire emergency
- Meets enhanced noise protection requirements
- Can be integrated into the lightning protection system
- Damage free construction
- Cost efficiency and cost certainty
- Sustainable in three dimensions
- Regarded as "energy-efficient façade"
- Ideal for renovations and to prevent corrosion
The best solution in terms of engineering design and construction engineering for solving the problem with moisture.
Moisture has always been present in our homes. But moisture seems to have increasingly become a problem due to modern construction methods and building materials. It is therefore appropriate to provide several explanations how such unwanted moisture is generated, and how the associated building damage can be prevented.
Where does the moisture come from?
Concerning the topic of moisture, most of us primarily think of outdoor weather influences. As protection against it, buildings are wrapped airtight. In doing so, little thought is given to the fact that the air circulating in the individual rooms also carries moisture. In addition, this air absorbs additional moisture due to cooking, washing, showering, perspiration, etc. As a result, approximately 6-14 liters of water per day can be discharged into the air by a three-person household. This indoor moisture results entirely naturally and is unavoidable. A certain level of moisture is also necessary for a comfortable indoor climate.
Why does this moisture become a problem?
The difficulty with moist air consists of the fact that it is essentially imperceptible. It slowly and unnoticeably releases its moisture to the environment. While excessive indoor moisture can be removed by ventilating regularly, this will cause a portion of it to be absorbed by the rooms and the masonry Moisture becomes a problem when the masonry is permanently exposed to moisture, and the moisture does not have a way of escaping.
This concentration of moisture in building elements results in unpleasant damage such as cracks in walls, mold infestations or the delamination of plaster and wallpaper and corrosion of reinforcements. Building elements begin to rot, their thermal insulation capacity is reduced, ultimately resulting in frost-induced spalling. Windows and doors begin to fog over and exhibit constant wetness particularly around the seal, which reduces the service life of materials and also promotes mold. The dew droplets can in this case cause consequential damage on windowsills and parquet floors. In order to avoid this, such locations need to be dried daily at great effort.
Careless and inappropriate handling of this inconspicuous moisture can therefore be a health hazard and result in damage to the building integrity.
How can this increased moisture in walls be explained?
In order to fully reach the origin of the problem, it is important to understand that a building is a foreign body in nature. The sealed exterior skin causes a climate disequilibrium that nature attempts to equalize. In spite of the latest technology, every building is subject to the laws of nature. It is little wonder then that undesirable moisture is formed in the building skin when these laws are not observed. In order to avoid this, it is important to understand what processes occur in a building.
Positive air pressure: The air in a building is heated up by heating or direct sun exposure. Heated air does expand and creates air overpressure. This results in a pressure decline between indoors and outdoors. This means that the air is pushing to the outside in an attempt to equalize the overpressure in the building with the low pressure outside.
Vapor diffusion: Diffusion is the process of compensating different gas concentrations that occur without external influences. This process occurs everywhere that a disequilibrium exists, and the cause for this is that hygroscopic (water-absorbing) materials attempt to equalize themselves to the indoor moisture level. The moisture generated in a room is therefore always evenly distributed throughout the entire living space and its skin. This means that a uniform moisture level is automatically created in a room between the materials and the ambient moisture.
For instance this becomes evident when a floor is wet-wiped. The visible moisture has disappeared after a few minutes. This drying process is caused by diffusion. The moisture on the floor diffuses into the remaining room and its furniture.
But the process does not end here. Instead – as already explained above – more moisture and air pressure is generated inside a building than outside, therefore resulting in so-called vapor diffusion. The tiny water molecules in this case penetrate to the outside through any available materials in an attempt to equalize the moisture level with the environment.
Temperature decline: Also concerning the temperature exists a disequilibrium in every building between the indoors and outdoors that nature attempts to equalize. Based on the temperature curve shown in the drawing, it is evident what this equalization looks like in an exterior wall. The temperature decline that we can identify in this case is important for understanding how undesirable moisture is created.
Dewpoint: The dewpoint is the temperature at which air can no longer absorb water vapor and water droplets are formed. As the ambient temperature drops, the air's ability to absorb moisture is reduced, resulting in condensation.
Summary: Due to Air overpressure and the natural laws of diffusion, the air in a building is in constant motion and pushes to the outside. This air carries water vapor that condensates by cooling off, resulting in undesirable moisture collecting on or in building elements. For that are not even particularly cold temperatures necessary – just the temperature decline is crucial.
Two case examples: The average outdoor temperature in the spring/fall is approximately 8°C. Assuming an indoor temperature of 20°C with a relative humidity of 65%. Based on the diagram its evident that the air reaches under this circumstances the dewpoint at 13°C, at which point condensation starts. If the air cools down to 8°C, it exceeds the dewpoint by 36.5%. If dew is already created under ideal conditions, how much more moisture must be expected as the outdoor temperature is reduced further at night or when the moisture level increases due to more persons in a household?
It is summer. The outdoor temperature measurement is 25°C with a relative humidity of 70%. It is only 19°C inside. The windows are now opened 2-3 times daily for ventilation. This causes hot air to flow into the room, which then cools off on the walls. The diagram shows that the air condensates on the walls under these conditions.
This again shows that even small temperature differences are sufficient to cause condensation. But since the average relative humidity is higher during summer, all the more of generated moisture need to be expected. In a thermally insulated building, one assumes a wall temperature between 15-16 °C since the heat is not on during the summertime. While this results in a pleasantly cool indoor climate, ventilating the room at the same time increases the formation of condensation.
Conclusion: Moisture is created where life happens, regardless of the season. These natural processes are unavoidable, even using the most sophisticated technologies. Since the physical properties of moisture cannot be disabled, this raises the question of the correct structure and construction methods.
What is the solution for the problem with moisture?
Building damage is already preprogrammed without a concept about how moisture can be dissipated. It is therefore important to create an enduring and sustainable solution. safe it GmbH gives you ideal solutions for the most demanding expectations that have already been proven on countless properties.
As already explant above can moisture not be prevented, but is much more a primary ingredient for a natural and healthy internal environment. This calls for a solution that creates a healthy balance. The initial position of our concept is that a pleasant and healthy indoor climate is created when building elements can breathe naturally and moisture is naturally equalized by diffusion. This is accomplished by utilize physical building attributes instead of antagonise them or try to control them artificially.
We offer a technically mature system to implement this. It is known by the name: Rear-Ventilated Facades (RVF) This highly effective construction engineering approach consists of precisely matched components. These include:
Support structure (1):
This represents the static link between the masonry (2) and the facade. It is anchored into the masonry and absorbs all loads, but does not transmit noise to the interior due to the thermal insulation element (3). The support structure consists of two parts and compensates for building carcass tolerances. The additional gliding points (4) allow the stress-free compensation of dimensional changes of the facade material during temperature changes.
The mineral-based insulation is applied directly to the masonry in two layers and fastened with insulation discs. DIN 18516 specifies that it must not be flammable and must only have limited water absorption capacity.
Facade cladding (6): The actual façade material is mounted onto the support structure and forms the exterior design skin of the building.
A space of 4-5 cm is required between the insulation and the façade material. This ventilation gap allows air to circulate behind the façade material, so that moisture generated by the building and its users can be released.
RVF prevents mold infestations based on natural vapor diffusion
The formation of mold is increasingly becoming a problem in our homes. The German Tenant Association (Deutscher Mieterbund - DMB) has determined that mold exists in at least one third of all residences in Germany. Mold infestation is not only unappetizing and aesthetically unpleasing, but also causes damage on the building structure and furnishings. Mold also is a long-term health hazard and can result in asthma, digestive problems, joint ailments, allergies, itchy eyes, itchiness, cardiac arrhythmia, and other diseases. The insidious nature of mold is also that it not always spreads in visible locations, but can also establish itself behind a material layer, to then discharge spores into the air from there.
How does mold arise?
Mold is undemanding and will find sufficient nutrients to establish itself in any residence. Fungi spores are in the air almost everywhere and need only very simple environmental conditions to grow as mold. The key ingredient in this case is sufficient moisture. Mold will prosper wherever there is sufficient moisture. It already gets critical when the relative humidity climbs above 65% for an extended period. Individual construction mold species already occur at a relative humidity of 70%, and almost all others starting at 80%.
What are the concrete causes for mold infestation?
Mold formation is always conceited with moisture and cold. One frequently attempts to remove the mold with various cleaning agents and miracle cures. But one will not get rid of the mold without understanding and correcting the causes for excessive indoor moisture. The following therefore takes a look at several specific causes:
Heating and ventilation:If mold forms in living areas, the most frequent cause is insufficient ventilation and heating. As the rise in heating costs exceeds the rise in wages, it is possible to observe societal changes with respect to heating and ventilation patterns. Energy costs can be reduced by about 6% for every one degree Celsius that the heat is reduced in a room. As a result, the heat in living areas is consistently reduced, while the windows are opened less for ventilation. This explains the increase in moisture in living areas. However, this raises the question: is ventilating and heating the only option to prevent mold as the moisture level increases? The answer is: YES! If the building does not have a constructively solution against cold and moisture, every resident is required to compensate themselves.
Building insulation: Nowadays, thermal insulation is a frequent cause for mold. The derogatory reporting in the media starting to increase dramatically ever since buildings started to get insulated in the mid 90s. Considerable monies were invested into insulating a building, but with the disappointing result that while heating costs were somewhat reduced, the desired living climate could not be achieved.
A key reason for this is that buildings equipped with the modern thermal insulation composite system (Wärmedämm-Verbundsystem - WDVS) are not able to "breathe" properly. The moisture exchange between the building and the outdoors is inhibited. The moisture level rises faster the better windows and walls insulate the living space. This results in an unpleasant moist climate that creates ideal conditions for mold. In order to avoid this, moisture must be released by the resident with proper heating and ventilating.
Building deficiencies by planning and construction:The prevention of building damage and mold already starts during the planning phase and requires proper construction. Possible issues that need to be avoided include:
- The routing of electrical cables is frequently overlooked. These frequently inadvertently create an outdoor-indoor connection. Cold air flows into the living space at the connection points, hot air is cooled down at the exit point, resulting in the formation of condensation and mold (as shown in the photograph).
- Water damage during or after the construction phase should not be underestimated. Frequently the problem is that the moisture is absorbed by the building structure and can then no longer escape through wall and floor layers. This results in rooms with a moldy odor that is caused by mold concealed in the building skin.
- Moisture from the outside is a treacherous enemy. Water can seep into the masonry through leaks in the roof. Moisture can also take advantage of the capillary effect to travel from the soil into the walls if a horizontal moisture barrier was not installed. A failure to observe this or deficient construction can impact an entire building and necessitate large scale renovations.
Thermal bridges: Improperly executed thermal insulation can promote mold. A thermal bridge is created when a small surface area of weakness in the thermal insulation is caused by geometry or constructive issues. These result in an increased flow of heat to the outside and therefore in reduced interior surface temperatures. Dew is formed in these areas in walls and ceilings as the hot indoor air cools down, which at some point will be followed by mold. Furthermore should here be mentioned that thermal bridge 20% to 40% of the entire heating demand.
Residual structural moisture:Today's fast construction methods already create the risk of mold when moving into new living space. The reason for this is the quantity of water needed for various building materials (such as gypsum, mortar, concrete, etc.). Following completion, all building elements therefore have an elevated moisture content. Depending on the construction method, the individual building elements require 2-4 years to dry out. The process does slow down further if the building exterior is insulated with Styrofoam. Tight insulation such as WDVS permit almost no moisture to escape directly to the outside. In such a case mold can form even with normal ventilation. Increased heating and ventilation are needed to avoid this.
What steps can be taken if a mold infestation is identified?
Frequently attempts are made to get rid of mold by cleaning the infested locations, repainting, or replacing wallpaper. However, this only displaces the mold and does not remove it. The mold will always return as long as the cause has not been addressed. Moisture and cold are the primary reason for mold growth in living areas. However, the problems with moisture are frequently more complex. We can help to address any questions you may have. As safe it GmbH we analyzes mold problems, supplies expert appraisals prepared by a publicly sworn construction appraiser, and offers constructive engineering solutions.
How can mold be prevented from forming?
This is stated repeatedly and seems to be the only solution in many buildings. However, it is not a blanket solution against moisture, and can result in increased mold if wrong applied:
- 2-3 short ventilation periods will help to release high levels of moisture, but are not sufficient to eliminate moisture that is absorbed and release e.g. overnight from walls, beds, wardrobes, etc.
- In order to permanently remove indoor moisture from living areas, windows are frequently tilted. This will cause the window soffit to cool off during winter, and has the effect of more condensation and mold in the window area. This also consumes heating energy.
- Due to the high levels of moisture during summer, one should ventilate at 4 AM during the daytime, and at 11 PM at night. One otherwise allows hot / moist air to enter the living area, which then condensates on the cool walls. But in most cases is this advice not something we want or can apply to.
Conclusion: In order to solve the problem of moisture in living areas, a better concept than simply ventilating correctly is needed. However, it is evident in this case that ventilating is inconsistent with saving energy.
Ventilation slots: In order to solve the moisture problem, several window manufacturers have started to install so-called slotted trickle vents into their window models. This consistently supplies rooms with a small amount of fresh air and allows moisture to escape. While this concept looks like a good solution at first glance, it brings various problems with it:
- In times of stormy weather and strong winds can appear some drafts for the resident.
Unpleasant odors and gases, e.g. along high-traffic roads, can enter the living space.
The biggest problem for this concept is the low noise and thermal insulation value. If a renovation does not improve these values, it raises the question of their benefit.
Ventilation system: Since today's building skins are increasingly becoming nearly air-impermeable due to the employed paints, insulation materials, and the very tight windows and doors, it is necessary to look after a solution for artificial air circulation. A ventilation system will ensure indoor air circulation and remove moisture. In addition to the positive effects, such as a reduction of heating costs, or protection against pollen for allergy sufferers, it is important to consider the following points of this system:
- When selecting such a system, the quality of the system should have a priority over the price. There are too many low-quality products on the market. This is often compounded by an inappropriately performed installation, which can result in the following problems: Improperly dimensioned pipes increase noise emissions, incorrectly positioned pipes limit air circulation, etc. An improperly performed installation will impact the air quality, the performance and efficiency.
- In order to facilitate optimum air circulation, all interior doors require a 10 mm bottom gap. This results in limited noise protection. Optimum values can still be achieved by equipping doors with professional Minergie drop seals. While these will improve noise protection, they also increase cost.
- Sound values can also be limitation by incorrectly installed ventilation pipes. It is therefore important to ensure that no connections are created between rooms to avoid sound bridges.
- Every building needs a master plan that is matched with the ventilation system. For instance, the steam discharge in the kitchen that blows air to the outside must be coupled with an additional makeup air source to prevent a pressure drop and air draft in the living space.
- The installing a ventilation system will cause additional costs and time. Costs for the ventilation system, controller, pipes, etc., and for additional design expenses to accommodate ventilation pipes in ceilings or floors, any required drilling, additional ventilation system space (for central ventilation), etc.
- Since a ventilation system strictly sucks in ambient air, unpleasant or unwanted odors can from time to time get in the entire living space. A farmer fertilizing his fields or a neighbor running his grill can become noticeable in the apartment. If someone is at home at this time, the option exists to switch the ventilation system off. But if nobody is at home at the time, we should not be surprised to find unusual odors in the apartment on our return.
- Ongoing operating expenses due to the continuous operation of the ventilation system.
- Regular service costs will accrue for filter swaps and pipe cleaning. This part is often neglect, which can result in elevated germ and microorganism's levels in the ventilation pipes. This results in hygiene problems and health hazards.
- Problems with moisture:
During winter, a ventilation system not equipped with a moisture compensation function may cause the humidity level to drop as low as 30% because the moisture content of the air sucked in from the outside drops dramatically when heated. This is not without problems and has the effect that flu viruses remain active for a longer time and causes mucous membranes to dry out. The propensity for infections and nosebleeds is increased, and the dryness may cause the skin to develop irritations, redness, and infections.
The opposite problem occurs during summer. On hot days, the outside air carries high moisture that the ventilation system pumps directly into the building. The moisture cools on walls and ceilings of indoor living space, which can result in condensation and mold.
Conclusion: With the assistance of the latest technologies, additional costs, and additional construction effort, a ventilation system can help to create a livable climate. This illustrates how elaborate and complex it can be to control the climate artificially. A artificially regulation of air without professional performance will create new problems! In addition, need to be taken care of regular service and cleaning of the ventilation system.
Rear-Ventilated Facades: Damage such as mold infestations can be prevented when the planning phase is approached conceptually and attention to the details is given. To avoid risks and to create a natural moisture equilibrium in indoor spaces we offer as safe it GmbH the ideal solution. As described in detail above, our rear-ventilation concept places façade material on substructure to facilitate rear-ventilation. In contrast to most other systems, this creates an vapor-barrier-free building skin that can absorb and release moisture, resulting in an improved living environment for better hygiene, health, and quality of life for every resident.
In additional can the following benefits be derived:
- It arises a rugged, enduring, and low maintenance building skin by eliminating susceptible materials and technology.
- The building skin can breathe naturally and therefore manages the moisture level naturally by absorbing or releasing moisture.
- Excess moisture can be released to the outside through the masonry and evacuated by the rear-ventilation.
- Residual construction moisture can escape to the outside and building elements dry out faster.
- The vapor-barrier-free structure prevents excess indoor humidity or moisture traps in the masonry, so that the living conditions for mold get eliminating.
- The images show that a vapor-barrier-free construction approach is ideally solved by a rear-ventilated façade (RVF). With a WDVS or Styrofoam insulation, the plaster is in direct contact with the insulation and therefore needs to also reject rainwater from the outside, while at the same time release excess indoor moisture to the exterior. It is questionable whether this can be reliably accomplished in spite of the strong development of new materials and technologies.
How need a vapor-barrier-free construction in comparison to be evaluated?
A question that is frequently asked is whether the system of a rear-ventilated facade (RVF) with a vapor-barrier-free building skin can meet the highest expectations even on large and elaborate projects. The answer is: RVFs are nowadays almost exclusively installed, specifically on large corporate buildings and rental properties. The reasons for this are: companies and landlords want a system that is rugged and non-susceptible to damage. It must be enduring and have low maintenance requirements, while also generating the lowest possible incidental or service costs.
If we apply these considerations to a passive house with a ventilation system and a classic thermal insulation composite system (WDVS) with a closed vapor diffusion structure, we find that it cannot meet these criteria. The reasons concerning the ventilation system were already discussed above, therefore we will in the following address several questions concerning WDVS facades:
- How long does such a façade keep its value, its strong color, and remain free of algae? How often does it need to be cleaned and repainted to keep its aesthetic appeal? Experience has shown that a new WDVS façade is indistinguishable from older ones after 2-3 years. And depending on the installation, the individual gaps between the Styrofoam panels become noticeable after a short time.
- This concept calls for a water and water vapor-tight façade. But is it even possible to create a completely tight building skin since leaks are repeatedly generated by building damage, holes and supply lines, or due to material weaknesses?
- Is it technically possible to create a tight facade? How long does the facade remain tight? Minor leaks can already result in building damage and will sooner or later require repairs and renovations.
- Do we know the exact service life of installed insulation and sealing materials? If we allow the climate in our buildings to depend on the service life and tightness of the material, mold will grow sooner or later without warning as their tightness fades away.
Conclusion: You are on the safe side with an open diffusion construction method. It is natural, healthy, enduring, and sustainable. It is maintenance free and easy to care for. It saves time and money, does not depend on electricity or the service life of insulation materials, and permanently prevents mold from getting a foothold.