Condensation Control

‘PIV Positive Pressure Unit’

Condensation is becoming an increasingly serious problem in dwelling houses, flats and office complexes. With the advent of more efficient insulation, and the upgraded draught-proofing capabilities of properties, this has proved to be an ever-increasing problem. The ‘PIV Positive Pressure Unit’ has been developed as a positive condensation control system. This prevents condensation occurring by feeding fresh filtered air into the building, the aim being to introduce a complete air change into the property every 45-75 minutes, in order to maintain the relative humidity levels low enough so that condensation may not form. This process reduces the build-up of high humidity, reversing draughts and reducing dust levels. There is medical evidence which indicates that a higher incidence of ill health occurs in damp and unventilated buildings that suffer from condensation, and accompanying mould and spore problems, than in those which are adequately ventilated. On average, a family of four can create two gallons of water vapour in 24 hours. Approximately 90% of condensation problems are due to excess moisture laden air being trapped. The Building Research Establishment lists the following household pollutants that occur throughout everyday living to be:

Carbon Monoxide
Pesticides
Radon Gas
Airborne Bacteria
Micro-organisms
Tobacco Smoke

Plus many other non-viable particulates. These problems are already causing severe discomfort and annoyance particularly in the home environment. By the simple process of introducing into the environment a positive controlled ventilation system, these problems can be eliminated. The ‘PIV Positive Pressure Unit’ has been designed to be cost effective and the installation to be unobtrusive. As the major body of the unit is located in the roof void, the only visible part is a 6” x 6” plastic diffuser (as shown in the diagram on the following page). This is centrally positioned in the ceiling of the first floor landing area. Installation of this system will not only eliminate excessive condensation build-up, but will provide a cleaner and more healthy, balanced atmosphere throughout the property.

PIV Positive Pressure Unit

The ‘PIV Positive Pressure Unit’ works by creating a slight positive pressure using fresh, filtered air which is drawn from the roof void, the effect being to push stale damp air out of the property through natural leakage points common to all properties (including those with draught-proofing and double glazing). Total control of the unit is achieved by adjustment of a control switch, which can be sited in a convenient position to avoid infant tamper and allow ease of accessibility and control. One of the main advantages of the ‘PIV Positive Pressure Unit’ is its’ economical running costs, the average costing less to run than a 30W light bulb. This gives the unit a major lead over other mains connected 13 amp methods which claim to eliminate condensation. These other methods, especially dehumidifiers and similar products, only ever remove moisture from the area in which they have been sited.

To achieve results similar to those of the ‘PIV Positive Pressure Unit’, it would be necessary to have several dehumidifiers working simultaneously throughout the property. The comparable cost of this would be prohibitive. In addition, the obtrusive nature and frequent necessity to empty dehumidifiers renders them an inferior method of condensation control.

With regards to installation, the ‘PIV Positive Pressure Unit’ can be fully installed and operational in approximately four hours with minimum disturbance to existing decorations and similarly minimal disruption to the occupants of the property. The installation is carried out by our fully qualified electrical engineer and all works are directed and supervised by our Survey Department. After installation, a period of approximately eight weeks must be allowed to enable the property to thoroughly air and dry. This drying out process includes all soft furnishings (carpets, curtains, ceiling and wall finishes etc.) and any other household items which may have been affected by the condensation problem. As part of our customer care policy, and to obtain comparisons of relative humidity in the property both before and after installation, West Midlands Timber Preservation and Damp Proofing Company will return to the property after this period at no extra charge to carry out a further relative humidity test. It will also be possible to provide a service agreement after the statutory 12 month guarantee period elapses whereby W.M.T.P. will contract annually for a quoted fee to clean and service the installed unit.

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BATHROOMS / KITCHENS

Bathrooms and kitchens, whether at ground or first floor level, are most susceptible to the effects of condensation. This is not surprising due to the volume of water used and consumed in these areas. A large proportion of this water is of a temperature which creates steam. The majority of bathrooms and kitchens in traditional properties had little or no ventilation incorporated in their original construction. This is wholly inadequate for the amount of moisture produced in these areas. This moisture then condenses on the cold walls and window panes. This causes the problems most often associated with condensation such as black mould (Aspergillus niger) and spore growth, de-bonding decorations and the saturation of ceiling and wall plaster. The provision of further natural ventilation often can be achieved by the installation of strategically sited high flow louvered air vents. If this is impractical or not an adequate solution then the introduction of some form of mechanical ventilation will be necessary. This could be in the form of a wall mounted humidity control extractor fan.

DOUBLE GLAZING

The UPVC and double glazing industry has grown dramatically in the last 20yrs. Advantages of UPVC double glazing / secondary glazing include low maintenance, and good thermal and acoustic insulation properties. This sealed unit concept has departed from the original softwood window and door design, which allowed a degree of natural ventilation through air leakage found in single glazed construction. Unfortunately, there is still a reluctance on the part of double glazing manufacturers to recognise the necessity of incorporating adequate ventilation in these window and door casements.

HEATING

Many properties, flats in particular, have a warm air ducted heating system installed. This type of system, while originally thought to be acceptable, creates very high moisture levels through the imbalance and incorrect siting of ducts and heat outlets. This imbalance occurs through a disproportionate heat delivery system, causing various areas of the property to become overheated whilst other areas are under heated. Also, moisture is circulated through the ducting and subsequently throughout the dwelling area. The modern preference for central heating is for gas fired radiated systems. These systems are vastly superior to their warm air predecessors, and if operated correctly, create no inherent condensation problems. Unfortunately there is a universal tendency to use the wall-mounted radiators for the purpose of drying clothes. This misuse creates a heavily moisture laden atmosphere and drives relative humidity levels higher throughout the property.

INTERNAL FITMENTS / FITTINGS

A common oversight in the introduction of fitted bedroom and kitchen units is the omission of any form of in-situ through or cross ventilation. These units frequently encapsulate the entire surface area of the wall to which they are fitted. Wardrobe units especially contain moisture laden clothing and footwear which create a stale, humid atmosphere which, when transferred to cold spots condenses, creating conditions conducive to the growth of mould and spores. These problems are mostly associated with modern living methods and can be overcome by the introduction of ventilation, both to the front panels of the units, and also to the exterior wall where possible.

CAVITY WALL INSULATION

Properties built between the late 50’s and mid 80’s of 11” cavity wall construction have been the target of aggressive advertising with regards to the merits of the installation of cavity wall insulation. The method of polystyrene in-fill often creates additional problems through uneven distribution of the in-fill material, and the creation of cold spots across the area of the wall. This problem is also increased if there is any obstructions within the cavity itself e.g. builders rubble or mortar droppings. This defeats the original design principle of the cavity wall, where moisture could evaporate naturally inside the 50mm void between the brickwork skins. This causes both the internal and external skins of brickwork to ‘sweat’ and increases moisture content, which is noticeable through staining visible on internal decorations. Although the installation of cavity wall insulation may seem financially attractive with regards to the savings achieved on heating bills, the adverse effect is to create a vacuous, over insulated property by not allowing the organic construction materials to function in the way they were originally designed. A full appraisal of the design of each individual property should be carried out before consideration is given to the installation of cavity wall insulation

CHIMNEYS AND FLUE SETS

Due to the introduction of the ‘smokeless zone’ and the prohibiting of the burning of fossil fuels, this has introduced the universal installation of central heating in to dwelling houses. If the original chimneys are capped, sealed and non-vented, this will cause ‘sweating’ and staining to occur, leading to the migration of salts and nitrates to the surface of the wall finish.

ROOF

Condensation can occur at roof level as well as at all other levels of dwelling houses, offices and flats. Roofing details are often designed to include provision for ventilation at eaves or soffit level. Because of there being so many exposed timbers in the roof construction of most properties, condensation in the roof space can cause many problems. When the Relative humidity of a roof space increases to the dew point, the timbers in that roof space begin to ‘sweat’. Over a period of time this will undoubtedly lead to problems with fungal decay and/or timber pest infestation. Plaster work to the ceilings below may also become affected by the high moisture content of the roof timbers. One of the most common causes of condensation in the roof space is over-insulation and the subsequent restriction of in-situ ventilation channels (e.g. soffit and eaves vents). Ventilation methods and channels should under no circumstances be blocked up to restrict the flow of air. If condensation is still present with the existence of in-situ ventilation, then additional roof slate and ridge tile vents can be installed on the slopes and ridges. In addition, high flow louvered air vents can be installed to any brick gables which may be present.

HABITUAL PATTERNS

When properties are unoccupied, generally little or no heating is required. This causes internal and external surfaces to remain cold. As a consequence of re-occupancy, normally in the early evening, moisture levels throughout the property are increased and air quality reduced through everyday activities such as cooking, bathing and respiration. This problem can be answered through a balance of both heat and ventilation working in conjunction. When this balance is achieved this will create a cleaner and more healthy living environment.

Summary

All of the above information is supplied by Ourselves as a guideline as to how condensation occurs throughout properties and the conditions which normally create condensation problems. These are the questions which are most frequently asked of our Surveyors when we are requested to investigate properties. The survey and report that has been commissioned by your good self will specifically identify the individual problems occurring throughout the property to which this report relates.

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The Homevent / F Positive Pressure Ventilation Unit

homevent-f-unit

Condensation is becoming an increasingly serious problem in dwelling houses, flats and office complexes. With the advent of more efficient insulation, and the upgraded draught-proofing capabilities of properties, this has proven to be an ever increasing problem. Condensation occurs as a result of too much moisture in the atmosphere (this is known as the relative humidity). This moisture builds up until it reaches a saturation point, or more commonly known as the ‘dew point’. Once the atmosphere within a property is saturated, then the moisture it carries begins to condense on contact with adjacent cold surfaces, for example window panes, window reveals and the cold external walls of the property. When this water condenses it then creates conditions conducive to fungal growth, and the presence of black mould (Aspergillus niger) and spores becomes apparent, this being most prolific to those areas of the property which are least ventilated or have the lowest temperatures.

The main contributory factor in the incidence of condensation is a restriction in the circulation of air around the property. To overcome this inadequate ventilation, the Home Vent range of ventilation products have been used for many years in properties to combat condensation and its’ accompanying problems.

The ‘Homevent / F’ has been designed specifically for flats and other properties of flat roof construction. It is a positive pressure ventilation unit, which incorporates a heat recovery facility. Positive pressure ventilation in properties which incorporate a roof void use pre-warmed air from the roof void itself to feed into the property. This is not the case in flat roof constructed buildings or high rise flats, where air must be taken directly from the exterior. Most positive pressure ventilation systems have no way of warming air prior to it entering the living areas, and many homeowners are unhappy at the thought of increased heating bills or reduced temperatures inside their property due to the introduction of cold air from the outside.

The ‘Homevent / F’ provides positive pressure ventilation to provide a continuous air change throughout the property, replacing stale, moisture laden air with fresh, filtered and warmed air into the living environment. The stale air passes over the heat exchanger which recovers the heat which is in turn used to heat the fresh incoming air. The ‘Homevent / F’ unit, with its’ unique heat recovery system, also reduces the need to increase heating when the introduction of fresh air from the outside is initiated, and will run on average at a cost of 30p per week (This is based on 90% trickle; 10% boost) Independent research shows that the use of an electric extractor fan will cost significantly more in heating bills alone.

The unit is fitted through the existing wall construction sloping slightly on the exterior brickwork face allowing moisture to fall away from the structure.

A major feature of the ‘Homevent / F’ heat recovery ventilator is their innovative air flow design. The moist warm air is sucked into the unit parallel to the wall surface. The then warmed fresh incoming air is pushed to the centre of the room, ensuring the minimal cross-contamination occurring between the two air flows. Twice incoming air volume will achieve the optimum in positive pressure ventilation throughout.

The ‘Homevent / F’ has many extra features as standard, including:

Whisper quiet running on trickle speed, guaranteeing minimal disturbance to the occupants of the property while the machine is in operation.
Safety Extra Low Voltage (SELV) – for bathroom and shower room fittings as required by the Building Regulations.
Humidistat controlled – The unit is operated by a humidistat control switch which constantly monitors the relative humidity of the property and adjusts the ‘Homevent / F’ accordingly.
Can be fitted internally – All fitting operations can be carried out internally, eliminating the need for scaffolding in high rise situations.

Another advantage of the ‘Homevent / F’ over other methods which claim to control condensation is its’ permanent siting as opposed to the temporary and localised positioning of e.g. dehumidifiers and similar products. These products only ever remove moisture from the immediate area in which they have been positioned. To achieve similar results to the ‘Homevent / F’ would necessitate the use of several dehumidifiers working simultaneously throughout the property. The comparable cost of this would be prohibitive. In addition the obtrusive nature and frequent necessity to empty dehumidifiers renders them an inferior method of condensation control.

The installation of the ‘Homevent / F’ is carried out by our fully qualified electrical engineers and all works are directed and supervised by our Survey Department. After the installation, a period of approximately eight weeks must be allowed for the property to thoroughly air and dry. This drying process includes all soft furnishings (carpets, curtains, ceiling and wall finishes etc.) and any other household items which may have been affected by the condensation problem.