Flat Roof Condensation Risk Analysis

This is to minimise any risk of harmful condensation.

Flat roof condensation risk analysis.

Flat roofs and low slope roofs also face potentially serious condensation problems that can in turn lead to costly rot or mold damage in buildings. A flat roof should be designed to minimise condensation and a condensation risk analysis should be undertaken taking into account positioning of insulating materials vapour control layers ventilation thermal insulation and the choice of materials. In order to predict any potential condensation before installing insulation a condensation risk analysis can be performed. This is something we do for all our new roofs as well as part of our design service.

Each of these constructions have draw backs to the building designer. Factors to take into consideration when designing out the risk of condensation include. The analysis will determine the dew point and you can check where the condensation is happening in the report. This takes into account winter condensation and summer evaporation.

Condensation can substantially reduce the performance of insulation and could affect a building s integrity. A condensation risk analysis is unable to allow for varying standards of workmanship but a high level of workmanship in itself would not mitigate potential issues. Because the waterproofing layer constitutes a vapour control layer on the cold side of the insulation there is a high risk of harmful interstitial and surface condensation on the underside of the deck or the upper surface of the insulation. Avoidance of gaps in the insulation.

As part of the design process a condensation risk analysis is performed to assess the annual build up. Avoidance of cold bridging. Determining the risk of interstitial or surface condensation in a building depends on the components of the assembly the order in which they appear in the construction the building s use and its geographical location. For a flat roof construction be it a cold roof a warm roof or a warm inverted roof the calculation method for year round condensation risk set out in bs en iso 13788 known as the glaser method is almost always sufficient.

As long as the roof accords with good practice then a more complex calculation method should not be necessary. If the dew point is within the buildup you have a problem. With a cold flat roof construction it is critical that a minimum of 50mm of cross ventilation is provided underneath the roof deck. While a flat or low slope roof can offer a long service life 20 years or more a small mistake can lead to a big leak.

This can be calculated using computer programmes.