condensation

One of a series of articles focussing on problem areas in buildings. 1) Examines condensation risks in buildings. Treats condensation processes, water vapour input and movement, conditions for surface and interstitial condensation in walls and roofs. 2) Treats condensation avoidance in general, humidity control, controlling vapour flow, adding insulation, heating, mould. Illustrates numerous examples diagrammatically from various building types.

A new Building Research Establishment audio-visual package, 'Remedies for condensation and mould in traditional housing' sets out the findings of field trials of some available remedies for condensation and mould, carried out in England and Scotland on estates which had a history of complaints of dampness. This research has led to a new understanding of the factors involved in the occurence of condensation and the ways in which they interact. Condensation is most likely to be a problem in the homes which use the least heating.

Dampness on the inside surfaces of dwellings is a frequent source of complaint. It may be due to rising damp, rain penetration or a plumbing defect; or it may be due to condensation. Condensation and mould growth are widespread problems in all housing sectors but especially so in tenanted accommodation. In many cases it may be difficult to identify the underlying cause; this can often be complicated by social issues. Mild cases will often yield to simple changes in the heating and ventilation regime in the dwelling or to cosmetic treatments of redecoration, perhaps with fungicidal paint.

This note arises from work to identify the effectiveness and cost of remedial treatments for condensation and mould problems in housing. Although the four factors - moisture generation, ventilation, insulation and heating - which control the likelihood of mould growths have long been established there hasnot been a straightforward way of showing their interrelationship, particularly where energy costs are important.

Factsheet includes useful chart on glazing materials. Gives basic advice on limiting heat loss from doors and windows, together with recommendations for materials and installation, Also deals with the new hi tech windows using heat reflective film, and problems of condens- ation.

Factsheet discusses types of air-to-air heat exchangers, their advantages and disadvantages, installation details, and how to select an air-to-air heat exchanger that is appropriate. Sections include how an air-to-air heat exchanger works, materials used for partitions, installation, condensation and frost removal, controls, maintenance, selecting a heat exchanger, and how much energy will be saved.

The article discusses how far the builder is to blame for condensation and its subsequent problems of mould growth. The UK Building Regulations of 1985 for ventilation and condensation do not go far enough in discouraging inadequate forms of

Failure to understand the principles appropriate to a particular roof makes it all too easy to introduce condensation problems, often serious ones. A distinction between surface condensation and interstitial condensation is made. Before attempting work on any roof it is necessary to determine how the roof is designed to work. If the principles are wrong, the whole design should be checked and if necessary corrected.

Draughtproofing the windows and external doors of UK dwellings can be an effective and relatively inexpensive means of comfort and reducing heat loss by natural ventilation. In most situations, draughtproofing is unlikely tocause any deterioration in the quality of indoor air. There are however a number of simple checks which should be made prior to installation to ensure that the ventilation requirements of the dwelling and its occupants are satisfied.

Points out that increased thermal insulation and draughtproofing of homes can increase the risk to health of indoor air pollution. Includes condensation as a pollutant along with associated mould growth. Notes collaboration by Pilkington the glass company and the Timber Research and Development Association plus Laing the housebuilding group, to combat condensation by passive ventilation. Treats sources of indoor air pollution - formaldehyde, asbestos, gas appliances, tobacco smoke, thoron, radon.