Discusses methods of preventing condensation: dehumidification, ventilation, controlling vapour flow; insulation and heating. Particular attention is paid to interstitial condensation and condensation in roofs
Discusses control of condensation, and moisture transfer through walls. Various air pressure barriers are suggested to control leakage. One-, two- and three-stage joint methods of wall construction are compared.
Test structures were constructed near Madison, Wis, USA and Gulfport, Miss, USA for exposure of eight types of insulated wall panels at controlled indoor conditions and typical outdoor weather conditions. Panels were instrumented with moisture sensors and tested without and with penetrations (electrical outlets) in the indoor surface. Continuous internal vapour barriers effectively prevented cold weather condensation in all panels. Installation of an electrical outlet changed moisture patterns in both the cold winter climate and the hot, humid summer climate.
Flat wood-frame house roofs with insulation applied between joists are susceptible to condensation problems in cold climates. Investigation of difficulties experienced in a wood-frame row housing project in Eastern Canada showed that many interrelated factors contribute to the occurrence of problems and demonstrated that control of air leakage through the ceiling is the one primary requirement for successful performance.
Presents four short articles treating aspects of building ventilation: 1) Achieving a balance - the work of the AIC, 2) House full of horrors - indoor air pollution and progress in eradicating hazards, 3) Letting off steam - test houses with ventilation system for condensation control, and 4) High and dry - condensation in the roof, eaves to eaves ridge ventilation.
Explains the principles involved in condensation and the conditions producing condensation, both atmospheric and other sources of moisture. The behaviour of absorbent materials and surfaces is described. Interstitial condensation is explained. Designing to avoid condensation, taking account of the characteristics of the building fabric and the environment, is necessary. A worked example of estimating condensation risk is given.
Describes the principal causes of condensation in dwellings in the UK. Monitoring the existing environmental conditions within a building, plus a structural and tenant survey, is required to determine the correct cure. Theinstrumentation and techniques are listed, and some solutions are suggested.
The current German Standard specifies a minimum thermal insulation. However even with excellent insulation, if the air change rate is too low, condensation can form. High humidity emissions in dwellings can require air change rates of more than 2/hour. The use of mechanical ventilation, possibly humidity-controlled and with a heat recovery system, is suggested to minimize ventilation heat losses. The user has to be educated to provide adequate ventilation in spring and autumn, but during the cold season the ventilation rate can be reduced to two thirds of the minimum value.