moisture

Rising moisture from the ground has caused quite a lot of damage on foundations of Swedish buildings, in particular for the type concrete slab on the ground. Some of these constructions may be repaired by mechanical ventilation, for example below the floor or below the concrete slab , if there is an air-permeable layer below the slab. Summarized results from a few field studies and tests, which have been going on for a period of 2-3 years, are reported. Different methods with mechanical ventilation systems have been found to work quite well so far, i.e.

Measurements in some dwellings show differences of the absolute humidity as a function of the kind of ventilation (only natural or mechanical exhaust air or balanced ventilation) and the position of the single rooms, especially of the bedrooms. Therefore is investigated into the expected moisture transport in two different ground plans. The main humidity production is in the kitchen and bathroom. If kitchen and bathroom are on the outer side, the dwelling is loaded with this moisture through the main wind direction.

This paper presents and discusses results of moisture transfer into timber frame constructions. The two mechanisms of transfer are diffusion and bulk air movement. Three defects in construction were monitored punctured vapour barrier, continuous path via an electrical socket and discontinuities at junctions. The study has shown that, under steady-state conditions condensation can take place, while under varying conditions both condensation and evaporation occur. This second case is typical of the building in use, and can prevent high levels of moisture existing in timber components.

DAMP is an 'Expert System' or 'Knowledge Based System' (KBS) to aid diagnosis of causes of moisture damage found in buildings in New Zealand. This paper gives an outline of the current version of DAMP, which is still under development at the Building Research Association of New Zealand, operating in the CLASS language developed at University of Auckland with BRANZ support.

The concern that a large number of housing units across Canada, and in particular, through Atlantic Canada are exposed to potential damage from wood rot due to moisture trapped within exterior walls caused a joint task force of Canada Mortgage and Housing Corporation and Canadian Home Builders Association representatives to address the "drying of walls" issue. Included in their mandate was a field research project in Atlantic Canada. The project, undertaken by Oboe Engineering Ltd. and AD1 Limited.

In this paper the moisture-diagnosis prototype of a knowledge based expert system to assist in the identification and diagnosis of air leakage problems in residential buildings is described and discussed. This prototype system requires the user to describe the symptoms of the existing moisture problems and provide information on house characteristics. Based on additional information on the symptoms and the house, this interactive program produces a list of probable causes and recommentations for remedial action.

Long term measurements of attic wood moisture content have shown that at least fifty kilograms of water may be stored in roof sheathing members over the course of the winter, to be released in the spring. Overlaid on this seasonal cycle there is a daily variation driven by temperature changes in the attic. A dynamic model is required to predict the resulting attic air humidity ratio. Hourly moisture flows in a typical attic - from ventilation and from the wood - are examined, and a simple first-principles dynamic mathematical model to relate them is developed.