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Water basically has three phases, a solid phase as ice, a liquid phase as water and a gas phase as water vapour. Believe it or not the air around you is not completely dry. All air will contain an amount of water, basically molecules of water floating around in the air in its gas phase. This is water vapour and is perfectly normal. The amount of water within the air is referred to as humidity.<\/p>\n\n\n\n
Air though only has an ability to hold so much\nwater before it becomes fully saturated and this ability is directly associated\nto its temperature. Warm air has a much greater holding capacity than cold air\nand as such is capable carrying more water vapour.<\/p>\n\n\n\n
We refer to this relationship as Relative Humidity,\nthe airs ability to hold water vapour relative to its temperature. This is\nusually expressed as a percentage (%RH). Therefore, when we say the humidity\nlevel is 60% RH (Relative Humidity) we\u2019re basically saying the air is 60% full\nof water vapour in comparison to it total holding capacity at that temperature.\nThat may sound like quite a lot however, at normal household temperatures it\nisn\u2019t really. What we consider dry air in our homes often varies between 50 –\n60% Relative Humidity. <\/p>\n\n\n\n
DEW POINT<\/p>\n\n\n\n
When the air reaches its maximum holding capacity,\nwe refer to the air as saturated. This is the limit where the air is unable to\nhold any more water vapour and as such, excess water vapour is dumped from the\nair as liquid water. This process is referred to as condensation. There are two\nmain causes for the process of condensation to occur. <\/p>\n\n\n\n
Firstly, a reduction in the air\ntemperature and therefore its holding capacity or secondly an increase in\nhumidity, basically more water vapour being added to the atmosphere.<\/p>\n\n\n\n
There is a calculated temperature of when\nair will reach saturation and this temperature is referred to as the Dew Point\ntemperature. This is the temperature at which condensation will form in the\ncurrent environment. The dew point temperature will change from environment \u2013\nenvironment dependent upon the conditions although a basic hygrometer or\natmospheric monitoring device will provide you with the calculated dew point\ntemperature. <\/p>\n\n\n\n
SPERCIFIC HUMIDITY <\/p>\n\n\n\n
Relative humidity is only a measurement of\nthe occupied volume of water in the air at a given temperature and does not\nrelate specifically to the mass of water present. The actual mass of water\nvapour is referred to as the airs specific humidity and is a direct measurement\nof water molecules in the air. This is not related to temperature and is\nusually measured in grams of water per kilogram of air or grains per\npound. <\/p>\n\n\n\n
VAPOR PRESSURE<\/p>\n\n\n\n
In addition, molecules of water suspended\nwithin the air also exert a force and increase pressure within the atmosphere.\nTherefore, warm humid air with lots of suspended water molecules will exert a\ngreater pressure than that of cooler, drier air. As such, the pressure of the\natmosphere as a result of its water content will cause the air to move. High\npressure forces will always overpower low pressure forces therefore, hot humid\nair will always move towards regions of lower pressure or regions of cooler\ndrier air. This is important to remember. <\/p>\n\n\n\n
EXAMPLE<\/p>\n\n\n\n
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To put the above into a practical sense, let\u2019s consider the following. You arrive at a petrol station to fill up your car. Your cars fuel gauge reads 1\/2 full, this means your tanks basically at 50%\u00a0of its holding capacity. This would be 50% Relative humidity. You wouldn\u2019t however know how many litres of fuel were in your tank unless you knew the size of your tank. If you had a 2000 Litre tank, 50% would be 1000 Litres. 1000 Litres would be your Specific humidity.<\/p>\n\n\n\n
<\/p>\n\n\n\n
<\/p>\n\n\n\n
WEATHER CYCLE<\/p>\n\n\n\n
Now let\u2019s put pressure, evaporation and condensation into practice. Consider a basic weather cycle. Water on land or in the sea is heated by the sun, when the suns energy is powerful this is enough to cause the water to evaporate as a gas (water vapour) into the air. This warm heated air, now laden with moisture rises into the atmosphere where the air pressure is lower. As the air rises it cools and eventually is unable to hold the water vapour it once did before. Clouds form, precipitation (condensation) occurs and the water falls back to land or sea.\u00a0<\/p>\n\n\n\n
<\/p>\n\n\n\n So now we understand a little bit more\nabout water vapour, humidity and vapour pressure why is this knowledge\nimportant within buildings. <\/p>\n\n\n\n Well, basically similar cycles occur\nwithin our homes. As occupants of a building we produce water vapour directly\nthrough breathing but also through our activities, such as cooking, washing and\ndrying clothes. This water vapour is suspended in the air within our homes and\nis managed through means of temperature control and ventilation. Problems\nhowever, will start to occur if there\u2019s is an in balance between the two. <\/p>\n\n\n\n Let\u2019s first look at the role temperature and air movement plays on the living environment.\u00a0<\/p>\n\n\n\n <\/p>\n\n\n\n TEMPERATURE<\/p>\n\n\n\n The air within the building has to be sufficiently warm and capable of holding the water vapour we produce as occupants. The air temperature must also be warm enough to ensure the fabric of the building, walls, floors and ceilings are also sufficiently warmed, keeping their surfaces above the dew point temperature of the atmosphere. Generally, we expect the air temperature within an occupied property throughout winter to be 21 degrees C and above. 21 Degrees is not only a comfortable temperature for the occupants but provides conditions capable of holding up to 15.7 grams of water, per kilogram of air, at idyllic humidity levels between 50 and 60% RH.<\/p>\n\n\n\n Provided there are no serious obstructions\nto the walls surfaces within your property you should find the surrounding wall\nand ceilings surfaces are approximately 2-3 degrees lower than the air temperature.\nUnder normal household conditions this should mean the surfaces are well above\ndew point. It\u2019s isn\u2019t however unusual to find these conditions exaggerated\nparticularly on older properties with solid external walls and ventilated suspended\ntimber floors where the temperature variance across a wall can vary in excess\nof 5 degrees from floor \u2013 ceiling. <\/p>\n\n\n\n The temperature of most properties\nis-controlled by a heating system and regulated often through a thermostat or\ntimer, which control the radiators or wall heaters. The location of these\nheating devices in rooms can be crucial to reducing risk of having condensation\nand mould related problems. Radiators \/ heaters should be sufficiently\npositioned to achieve maximum radiation of heat within a room, therefore not\nbehind couches or curtains. In most older properties you\u2019ll often find\nradiators are positioned on the coldest external walls and beneath windows\nhowever, on modern properties it\u2019s much more common to find heat sources on\ninternal dividing walls often back to back in adjacent rooms. This is a poor\nconsideration to the heating of a building and was implemented basically as a\ncost saving measure on labour and material during installation rather than\nperformance. A prime example of design considering expense before\nperformance. <\/p>\n\n\n\n <\/p>\n\n\n\n ORIENTATION<\/p>\n\n\n\n The most problematic elevations are likely to be the North facing elevation of any building and this is due to its orientation and absence of solar gain. As such, the walls and fabric of the building do not benefit from the heat of the sun making the North a much colder elevation. It\u2019s is however, important to mention that any elevation which is shaded can be at similar risk, opposing gable ends on terraced properties and large tree lined boundaries can also be problematic for the same reason. <\/p>\n\n\n\n Similarly, internally the position of furniture\nand belongings, particularly built in wardrobes and cupboards which restrict the\nability of warm heated air to pass over a walls surface have a similar effect.\nWith the exception of possibly being able to reposition furnishings there may\nbe little that can be changed regarding orientation and shaded elevations. In\nthis circumstance the placement of heat sources internally such as radiators\nplay a more crucial role is reducing the risk. <\/p>\n\n\n\n Options are available to help raise the\nsurface temperature of vulnerable surfaces such as; internal, external and\ncavity wall insulation however, diligence needs to be undertaken with any of\nthese improvements as they can sometimes create further problems. <\/p>\n\n\n\n <\/p>\n\n\n\n AIR MOVEMENT <\/p>\n\n\n\n If we refer to vapour pressures above, you\u2019ll remember that moisture laden air excerpts a pressure on the atmosphere and that high pressure will always shift towards regions of low pressure. As such, you can expect the water vapour you produce internally\u00a0will naturally shift towards regions of lower pressure. In this county 90% of the time the air vapour pressure externally will be lower than the air vapour pressure internally. This means that the air within your building is always trying to escape. That\u2019s why most condensate \/ mould related problems are most likely seen on external walls and cold ceilings. This is basically warm, wet air trying to escape.\u00a0<\/p>\n\n\n\n To a lesser degree these heated air presure\nchanges also exist internally. Air within the centre of the room is often much\nwarmer with lower humidity levels than the air adjacent your walls, ceilings or\nwindow surfaces. This is simply the result of the surrounding surfaces being\nslightly lower in temperature than the air. As such when the air which is\ncentral to the room moves towards these cooler surfaces the air then cools and\nits humidity level increases. This can result in a layer of cooler more humid\nair usually within an inch of the surface. We refer to this as the boundary\nlayer of air. Usually this air will be prevented from becoming stagnant\nadjacent walls and ceiling surfaces by convectional air currents although\nobstructions from furniture may impede. That\u2019s why where possible you should\nensure furniture is stood back from walls by a few inches to help the air\nbehind circulate. <\/p>\n\n\n\n <\/p>\n\n\n\n Air also tends to move in a circular motion and as such the corners of rooms are the most vulnerable where the air tends to sweep around the internal corners of external walls leaving the boundary layer air undisturbed. It doesn\u2019t help that most homes often have televisions, wardrobes, couches and other items of furniture close to the walls. In this circumstance you\u2019ll often notice a sweeping tide mark of mould or surface moisture deposits either from the floor upwards or ceiling level downwards, this is simply a cold region of lower pressure where air movement is limited.\u00a0<\/p>\n\n\n\n <\/p>\n\n\n\n INSULATION<\/p>\n\n\n\n Insulation is a crucial component of a building ensuring surfaces within the building remain warm\u00a0via the radiated heat of the heating system. Areas of absent or disturbed insulation within walls, floors and ceilings can create vulnerable cold spots across an otherwise uniformed temperature surface. <\/p>\n\n\n\n Sloping skielings which protrude into rooms are common in post war properties and can be extremely problematic due to absent insulation, an issue which is often highlighted when the accessible sections of a roof void are insulated from above. <\/p>\n\n\n\n This scenario creates a significant thermal variance across the ceiling between the warm insulated section and the cold uninsulated section which inevitably becomes problematic with mould. Similarly, flat, roofs, protruding bay windows and poorly designed garage conversions can also be problematic for similar reasons. <\/p>\n\n\n\n A lot of the time in this scenario the\ninsulation is blamed as the cause however, in my experience this isn\u2019t always true.\nThe insulation may well reduce the permeability of the of the structure encouraging\nwarm moisture laden air to remain within the property. A similar scenario exists\nwith retro cavity wall insulation. I often find however that these retrofit\ninsulation measures are poorly considered and only highlight inadequacies in\nventilation that existed within the property prior. <\/p>\n\n\n\n <\/p>\n\n\n\n MOULD <\/p>\n\n\n\n Contrary to the belief moulds are not plants, moulds actually belong to the kingdom of living organisms Fungi, moulds are simply micro-fungi.<\/p>\n\n\n\n Moulds and fungi, also unlike plants do not contain\nchlorophyll, therefore do not derive their energy from sunlight, hence the\nreason why most moulds prefer dark, damp conditions. It is common nonetheless,\nto see moulds\/fungi living symbiotically with plants, as each contribute to this\nmutual relationship. Moulds and fungi perform the laborious task of breaking\ndown complex organic substances into simple food compounds for plants in\nexchange for sugars and energy derived by the plant through photosynthesis.<\/p>\n\n\n\n It\u2019s important to mention that moulds are the result of high humidity and not necessarily condensation, therefore it\u2019s perfectly possible to have mould problems without physical condensation. Both are nevertheless an issue. Most Moulds don’t require the presence of physical water to germinate only humidity levels sustained above 80% Relative humidity for a period of 48 – 72 hours. We often refer to dry air as having 60% or less of its holding capacity, however this isn’t as severe as it sounds. To live comfortably we require the presence of moisture in the air to make the air comfortable and breathable, totally dry air would be intolerable. The intention of the Act is to\nensure that all tenanted properties both social and private are fit for human\nhabitation by maintaining decent standards which do not place the health and\nsafety of the tenants at risk. This applies both at the start of the tenancy\nand throughout its duration. The new homes Act however goes beyond the\nparameters of the prior ‘Landlord and Tenant\u2019 Act and now provides the power\nfor tenants to take legal action against landlords without having to wait for the\nCouncil or Environmental Health. <\/p>\n\n\n\n The vast majority of landlords already take their\nresponsibilities and tenants\u2019 risk to health seriously. The act merely means to\nimpose upon those who do not. It is however important to mention that whilst\nlandlords have a responsibility to ensure that properties are provided with\nadequate means of ventilation and are free from damp, it is the tenants\nresponsibility to ensure that facilities provided are used, and that they\nthemselves are not contributory to the cause.<\/p>\n\n\n\n So,\nwhat constitutes as ‘unfit’ for human habitation? <\/p>\n\n\n\n A property is classified as\nunfit for human habitation if it achieves a category one hazard in one or more\nof the following:<\/p>\n\n\n\n Repair\n– is in a poor state of\nrepair <\/p>\n\n\n\n Damp \u2013 suffers from serious issues with damp\npenetration, rising damp, water ingress or condensation. <\/p>\n\n\n\n Ventilation – inefficient means of ventilation both\nnatural and mechanical <\/p>\n\n\n\n Stability\n– has structural integrity\n\/ stability issues<\/p>\n\n\n\n Water,\nheating and sanitation –\npoor quality water supply or sanitation<\/p>\n\n\n\n Preparation\nFacilities \u2013 Poor quality\nfood and cooking facilities <\/p>\n\n\n\n Dangers \u2013 has defects considered dangerous to\nhealth. Section 4 of the Defective Premises Act 1974 places a duty on landlords\nwho are contractually obliged to maintain or repair premises, to take\nreasonable care in the circumstances to ensure that anyone likely to be\naffected by defects in the premises are reasonably safe from personal injury,\nor from damage to the property caused by a relevant defect. <\/p>\n\n\n\n Under the new Homes Act, if one\nor more of the above are considered a serious category one defect landlords\nhave a legal obligation to correct them. Even if some complaints do not meet a\ncategory one under the HHSRS risk assessment they may still be considered a\n”Statutory Nuisance’ and can be reported to the local council for an abatement\nnotice. <\/p>\n\n\n\n EXCEPTIONS\nFOR LANDLORDS<\/p>\n\n\n\n There are however some exceptions where a landlord\u2019s\nresponsibilities cease:<\/p>\n\n\n\n Where repair works are the responsibility of a superior\nlandlord such as, a management company or where third party consent is needed.<\/p>\n\n\n\n I hope this article has gone some way to aiding your\nunderstanding your understanding about condensation \/ mould related problems or\nat least refreshed your memory about the some of the problems \/ challenges we\nas surveyors will face over the forthcoming months. <\/p>\n\n\n\n Happy surveying <\/p>\n\n\n\n Russell <\/p>\n\n\n\n A brief article about the causes of Condensation, Mould and High humidity <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":true,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,5,4,7,21,10,3],"tags":[89,11,133,60,102,131,132,130],"class_list":["post-1099","post","type-post","status-publish","format-standard","hentry","category-all-posts","category-condensation-high-humidity-relative-humidity-mould","category-damp-related-posts-written-by-our-team-of-qualified-building-surveyors-of-real-every-day-inspections","category-energy-efficiency-insulation-improvements","category-mould-remediation","category-surveying","category-thermography-thermal-imaging","tag-condensation-high-humidity-relative-humidity-mould","tag-damp","tag-humidity","tag-mould","tag-survey","tag-thermal","tag-thermal-imaging","tag-ventialtion"],"_links":{"self":[{"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/posts\/1099","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/comments?post=1099"}],"version-history":[{"count":5,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/posts\/1099\/revisions"}],"predecessor-version":[{"id":1116,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/posts\/1099\/revisions\/1116"}],"wp:attachment":[{"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/media?parent=1099"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/categories?post=1099"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dryfix.net\/blog\/wp-json\/wp\/v2\/tags?post=1099"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/dryfix.net\/blog\/wp-content\/uploads\/Water-Cycle-Art2A-1024x524.png\")
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Tipping the balance over 60% relative humidity towards 80% relative humidity isn’t however that difficult when we consider the number of wet or moisture producing activities we undertake within our homes. Irrespective of this we really shouldn\u2019t be creating conditions which are conducive to mould growth in our homes and the levels of ventilation and thermal insulation should be sufficient it keep our homes warm and dry.
Moulds require three basic fundamentals for their survival food, oxygen and water, and the first two are present in all atmospheres therefore fundamental for their growth is always the availability of water. Moulds also favour cellulose materials such as paper, fabrics, leather and wood therefore ideally its best to avoid these in high moisture producing rooms. Wall papers is bathrooms is a definitive no, no!
If moulds do germinate many people treat them with a fungicide although in my opinion this is often a pointless exercise. When a surface is cleaned and treated for the eradication of mould, it is only clean for that moment in time. After the cleaning process the surface will inevitably only become dirty again. Mould spores within the atmosphere will land once again upon the surface regardless of its treatment of not and if conditions remain the same, over time these will germinate. As such, it is critical that if certain parts of the structure are problematic with mould that the cause is identified and corrected rather than the using cleaning as an expedient to the cure.
Not all moulds are bad, remember moulds and fungi contribute to the valuable chain of our eco system, breaking down complex organic substances into simple compounds and molecules to digest forming natures very own organic recycling process. Without moulds and fungi this process would simply end and the world would consume itself buried in a trail of matter.<\/p>\n\n\n\n
The Homes Act 2018<\/p>\n\n\n\n![\"\"](\"https:\/\/dryfix.net\/blog\/wp-content\/uploads\/Homes__Fitness_for_Human_Habitation__Act_2018.png\")
The Homes Act 2018 came into force on the 20th March and amended the prior ‘Landlord and Tenant Act of\u00a01985’ by extending the Acts obligations ensuring tenanted properties are \u2018Fit for Human Habitation\u2019.<\/p>\n\n\n\n![\"\"](\"https:\/\/dryfix.net\/blog\/wp-content\/uploads\/Image2-1.jpg\")
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